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Standard Handbook for Mechanical Engineers

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Correlation of Yield Strength and Tensile Strength

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The yield point determines the limits of performance for mechanical components, since it represents the upper limit to forces that can be applied without permanent deformation. In structural engineering, this is a soft failure mode which does not normally cause catastrophic failure or ultimate failure unless it accelerates buckling.

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Chicago Topics & News Visual Dictionary Field Trips Families & Camps Teens Educators & Mentors DiscoverDesign.org Membership Donations Corporate Involvement Volunteer Home Architecture & Chicago Visual Dictionary

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Buildings of Chicago Topics & News Visual Dictionary

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Architectural drawing/ Line weight & types

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The practice of architecture drawing follows some standards and these standards are used for both manual and computer drafting. One of the most essential standards is the weight and type of lines or in other words the vocabulary of lines.

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truss, in architecture and engineering, a supporting structure or framework composed of beams, girders, or rods commonly of steel or wood lying in a

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The hatched area is referred to as the tributary area for the joist. It's dimension transverse to the joist is half the distance to the next joist on either side (also known as the tributary width) and it's length is the length of the joist.

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The diaphragms are considered simply supported beams with uniform loads. The diaphragms are supported by the walls at either end of the diaphragm that are parallel to the direction of force.

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Strength Of Materials. Definitions Of Terms

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Stress This is the cohesive force by which the particles of a body resist the external load that tends to produce an alteration in the form of the body. Stress is always equal to the effective extern...

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Strain, Stress, And Deformation In Structural Engineering

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Applied load and stress will cause deformation, or strain in construction materials. Characterizing the limits of allowable strain is another fundamental analysis in structural engineering. Anticipating worst case deformation and strain in a structure can mean the difference between a successful design and disaster.

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Structure is an assemblage of a number of components like slabs, beams, columns, walls, foundations and so on, which remains in equilibrium. It has to satisfy the fundamental criteria of strength, stiffness, economy, durability and compatibility, for its existence. It is generally classified into two categories as Determinate and Indeterminate structures or Redundant Structures.

Any structure is designed for the stress resultants of bending moment, shear force, deflection, torsional stresses, and axial stresses. If these moments, shears and stresses are evaluated at various critical sections, then based on these, the proportioning can be done. Evaluation of these stresses, moments and forces and plotting them for that structural component is known as analysis. Determination of dimensions for these components of these stresses and proportioning is known as design.

Determinate structures are analysed just by the use of basic equilibrium equations. By this analysis, the unknown reactions are found for the further determination of stresses. Redundant or indeterminate structures are not capable of being analysed by mere use of basic equilibrium equations. Along with the basic equilibrium equations, some extra conditions are required to be used like compatibility conditions of deformations etc to get the unknown reactions for drawing bending moment and shear force diagrams.

Example of determinate structures are: simply supported beams, cantilever beams, single and double overhanging beams, three hinged arches, etc.

Examples of indeterminate structures are: fixed beams, continuous beams, fixed arches, two hinged arches, portals, multistoried frames, etc.

Special methods like strain energy method, slope deflection method, moment distribution method, column analogy method, virtual work method, matrix methods, etc are used for the analysis of redundant structures.

Indeterminate Structures: a structure is termed as statically indeterminate, if it can not be analysed from principles of statics alone, i.e. . A statically indeterminate structure may be classified as:

1. Externally indeterminate, (example: continuous beams and frames shown in figure-1(a) and (b)).

2. Internally indeterminate, (example: trusses shown in figure-1(c) and (d)).

3. Both externally and internally indeterminate, (example: trussed beams, continuous trusses shown in figure-1 (e) and (f)).

Figure.1

EXTERNALLY INDETERMINATE STRUCTURES:

A structure is usually externally indeterminate or redundant if the reactions at the supports can not be determined by using three equations of equilibrium, i.e. . In the case of beams subjected to vertical loads only, two reactions can be determined by conditions of equilibrium. Therefore, simply supported cantilever and overhanging beams shown in figure 2 are statically determinate structures.

Figure 2

If however a beam rests on more than two supports or in addition any of the end support is fixed, there are more than two reactions to be determined. These reactions can not be determined by conditions of equilibrium alone. The degree of indeterminacy or redundancy is given by the number of extra or redundant reactions to be determined. The beam shown in figure 3 (a) is statically indeterminate to one degree because there are three unknown reactions and statics has only two reactions. The beam in figure 3(b) is statically redundant to two degree. The beam in figure 3(c) is redundant to three degree and the beam in figure 3(d) is redundant to four degrees.

Figure 3

A portal frame is statically determinate if there are only three external reactions, because there are three conditions of equilibrium for such a system. The portal frame shown in figure 4 are statically determinate because there are only three reactions to be determined. If a portal frame has more than three reactions it is statically indeterminate, the degree of indeterminacy or redundancy being equal to the number of redundant or extra reactions to be determined. Therefore, the portal frames of figure 5(a) and (b) are redundant by one degree, that of figure 5(c) is redundant by two degrees, that of figure 5(d) is redundant by three degrees, and that of figure 5(e) is redundant by 5 degrees.

Figure 4

Figure 5

The statically indeterminate beams and frames can be analysed by strain energy method, three moment equation, slope deflection method or moment distribution method.

INTERNALLY INDETERMINATE STRUCTURES:

A truss is statically determinate internally if the total number of members
m=2j - 3
where j= number of joints.

A truss having more than (2j - 3) members is statically indeterminate or redundant, the degree of indeterminacy or redundancy being equal to the number of extra members.

Figure 6

Thus the truss shown in figure 6(a) is statically redundant by one degree because there are 14 members and 8 joints.

Number of redundant members = m= 2j - 3

= 14 - (16 - 3) = 1

Similarly, the truss shown in figure 6(b) is internally redundant by two degrees.

The internally indeterminate trusses can be analysed by strain energy method.

EXTERNALLY AND INTERNALLY INDETERMINATE STRUCTURES

A truss is statically determinate, both externally and internally when

(a) All the reactions can be determined from the conditions of equilibrium, namely , and

(b) The total number of members, m= 2j - 3, where j= number of joints.

The truss shown in figure 7 is externally indeterminate to one degree because the numbers of reactions to be determined are three, and the conditions of equilibrium reduces to two, namely . This truss is also internally indeterminate to one degree because there is one extra member.

Number of redundant member = m - (2j - 3)= 22 - (2 x 12 - 3)= 1

Such trusses can be analysed by using strain energy method.

Figure 7
DIFFERENCE BETWEEN DETERMINATE AND INDETERMINATE STRUCTURES

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Structure is an assemblage of a number of components like slabs, beams, columns, walls, foundations and so on, which remains in equilibrium. It has to satisfy the fundamental criteria of strength, stiffness, economy, durability and compatibility, for its existence. It is generally classified into two categories as Determinate and Indeterminate structures or Redundant Structures.

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Determinacy, Indeterminacy and Stability - EngineeringWiki

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This section will explain the concepts of determinacy, indeterminacy and stability and show how to identify determinate, indeterminate and stable structures.

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Look up stability in Wiktionary, the free dictionary.

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Dictionary of Architecture and Landscape Architecture

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Home College & Higher Education Pathways Dictionaries

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spread footing or foundation - Dictionary definition of spread footing or foundation | Encyclopedia.com: FREE online dictionary

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Definition of spread footing or foundation - Our online dictionary has spread footing or foundation information from A Dictionary of Architecture and Landscape Architecture dictionary. Encyclopedia.com: English, psychology and medical dictionaries

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relies largely or entirely on a single source .talk page. Please help improve this article by introducing citations to additional sources.

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american institute of architects Grace Construction High-Temperature Roofing Underlayment Grace Construction Products

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Electricity-Free Heater Uses Candle Power

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National Mall Dr. Miriam & Sheldon G. Adelson School of Entrepreneurship

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Architect Magazine: Architectural Design | Architecture Online: The premier site for architecture industry news & building resources for architects and architecture industry professionals.

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Now in its 2nd edition, The Architecture of Tilt-Up is the industry's premier resource for design professionals and owners.

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Structural efficiency is a function of the weight of structure to the afforded ships strength. Naval architects strive to maximize structural efficiency by minimizing the weight, while still providing adequate strength (it is not a matter of structural minimization). Scantings, materials, etc. can all be varied to achieve this goal (see stuctural design for the design process).

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tensile strength

The resistance of a material to a force tending to tear it apart, measured as the maximum tension the material can withstand without tearing.

tensile strength

n

(General Physics) a measure of the ability of a material to withstand a longitudinal stress, expressed as the greatest stress that the material can stand without breaking

ten′sile strength′

n.

the resistance of a material to longitudinal stress, measured by the minimum amount of longitudinal stress required to rupture the material.

ten·sile strength
(tĕn′səl, tĕn′sīl′)

The ability of a material to resist a force that tends to pull it apart. It is usually expressed as the measure of the largest force that can be applied in this way before the material breaks apart.

Noun 1.

tensile strength - the strength of material expressed as the greatest longitudinal stress it can bear without tearing apart

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Define tensile strength. tensile strength synonyms, tensile strength pronunciation, tensile strength translation, English dictionary definition of tensile strength. n. Abbr. TS The resistance of a material to a force tending to tear it apart, measured as the maximum tension the material can withstand without tearing.

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OTM '09 Proceedings of the Confederated International Workshops and Posters on On the Move to Meaningful Internet Systems: ADI, CAMS, EI2N, ISDE, IWSSA, MONET, OnToContent, ODIS, ORM, OTM Academy, SWWS, SEMELS, Beyond SAWSDL, and COMBEK 2009

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Spray polyurethane foam is widely promoted as a green building material for its ability to improve energy efficiency. It insulates better per inch than fiberglass or cellulose, which can mean major energy saving on heating and cooling. However, energy efficiency isn't the only consideration when it comes to sustainable building. A closer look at spray foam's chemical makeup reveals a number of substances that are known to be hazardous.

Spray polyurethane foam consists of two liquid chemical components, referred to as "Side A" and "Side B," that are mixed at the site of installation. Side A is mostly made up of isocyanates, while Side B usually contains polyol, flame retardants and amine catalysts. These chemicals create hazardous fumes during the application, which is why installers and nearby workers should wear personal protective gear during this process. Once the foam has fully expanded and dried, manufacturers say it is inert. If the chemicals are not properly mixed, they may not react fully and can remain toxic.
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The risks associated with the isocyanate of Side A are relatively well-documented, but risks associated with Side B are less well understood. David Marlow at the Centers for Disease Control has been researching off-gassing associated with spray foam installation since 2010. Although Marlow was unavailable for interview, the Public Affairs office at the CDC was able to provide information about his ongoing research via email. These field studies aim to determine the extent of exposure to all the chemical components of spray foam, determine a better understanding of curing rates and establish safe reentry times, and develop engineering controls to reduce the risk of exposure.

In addition to the dangers associated with installation, these chemicals can potentially remain unreacted in the form of dust or shavings. The Environmental Protection Agency warns: "Cutting or trimming the foam as it hardens (tack-free phase) may generate dust that may contain unreacted isocyanates and other chemicals." This is also a concern during the process of removing foam.

Isocyanates

Isocyanates, such as methylene diphenyl diisocyanate (DMI), are found in the "Side A" of the spray foam mix. Isocyanates are also found in paints, varnishes and other types of foam. They are a known cause of occupational asthma. According to Dr. Yuh-Chin T. Huang, a professor at Duke University Medical Center, isocyanate-induced asthma is similar to other types of asthma, but instead of being triggered by exercise, it is triggered by exposure. Once someone has become sensitized, re-exposure can cause intense asthma attacks.

Homeowner Keri Rimel says she and her husband have both become extremely sensitive to isocyanates and other chemical smells following exposure during spray foam installation. "He still to this day can walk into any restaurant, home or office and he can immediately tell if there's spray foam in a building," said Rimel of her husband.

According to the CDC, direct contact with isocyanates can also cause a rash if it comes in contact with the skin.

Amine catalysts

Amine catalysts are one of the Side B chemicals that the CDC is researching, in an effort to understand the levels of exposure during installation. "Amine catalysts in [spray polyurethane foam] may be sensitizers and irritants that can cause blurry vision (halo effect)," they write.

According to a report published by the Consumer Product Safety Commission, amine catalysts can also irritate the eyes at even low concentrations and if ingested "may result in severe irritation, ulceration, or burns of the mouth, throat, esophagus, and gastrointestinal tract."

Polyol

Also found in side B, polyols are alcohols that serve as catalysts. Polyols are usually made from adipic acid and ethylene glycol or propylene oxide. Some polyols are made from soy, but according to the Pharos Project, an organization that advocates for building material transparency, the soy-based material makes up just 10 percent of the final insulation.

Ethylene glycol, a chemical used to produce polyol in some spray foam, can in cases of acute exposure (such as swallowing) cause vomiting, convulsions and affect the central nervous system. According to the EPA, exposure by inhalation can cause irritation in the upper respiratory system and studies in animals have shown kidney failure.

Flame retardants

Flame retardants are added to Side B to pass flammability tests in building codes. The main fire retardants used in spray foam are hexabromocyclododecane (HBCD or HBCDD) and tris(1-chloro-2-propyl) phosphate (TCPP).

According to the Centers for Disease Control, "flame retardants, such as halogenated compounds, are persistent bio accumulative and toxic chemicals." Bioaccumulation means that a chemical builds up in the body faster than it can be flushed out, so there can be a risk of chronic poisoning even if the level of exposure is low. The chemicals also build up in the ecosystem, where they enter the food chain.

A paper by Vytenis Babrauskas published in the journal Building Research & Information says that, "flame retardants whose primary use is in building insulation are found at increasing levels in household dust, human body fluids and in the environment." The paper also cites several other studies that show these chemicals are associated with endocrine disruption and are potentially carcinogenic.

The chemical question mark

In a post for the CDC, Marlow describes the components of Side B as "a chemical question mark." He described the need for "real world sampling."

In addition to those listed above, there may be other chemicals used in spray foam that are undisclosed, and are protected trade secrets. This is particularly troubling for homeowners who want to have their air tested, because they won't know which tests to have done. "You have to tell the person testing what you're looking for," says Terry Pierson Curtis, an indoor air quality specialist. "The problem a lot of times is trying to figure out what you're looking for."
NEXT: Spray Polyurethane foam manufacturer may face class-action lawsuit See all our posts on insulation
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Chemicals in spray polyurethane foam: How can something so toxic be considered green?

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Spray polyurethane foam is widely promoted as a green building material for its ability to improve energy efficiency. It insulates better per inch than fiberglass or cellulose, which can mean major energy saving on heating and cooling. However, energy efficiency isn't the only consideration when it comes to sustainable building.

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What is slab on grade? definition and image

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Definition of slab on grade: A concrete slab placed on grade, sometimes having insulation board or an impervious membrane beneath it.

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National Roofing Contractors Association How

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Single-ply membranes | Everybody Needs a Roof

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Shoring is used on board when damage has been caused to a vessel's integrity, and to hold leak-stopping devices in place to reduce or stop incoming water. Generally consists of timber 100 mm x 100 mm and used in conjunction with wedges, to further jam shoring in place, pad pieces to spread the load and dogs to secure it together.

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Reinforced concrete

Type

Composite material

Tensile strength (σt)

Stronger than concrete

Reinforced concrete ( RC), also called reinforced cement concrete ( RCC), is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility. The reinforcement is usually, though not necessarily, steel bars ( rebar) and is usually embedded passively in the concrete before the concrete sets. Worldwide, in volume terms it is an absolutely key engineering material.

Reinforcing schemes are generally designed to resist tensile stresses in particular regions of the concrete that might cause unacceptable cracking and/or structural failure. Modern reinforced concrete can contain varied reinforcing materials made of steel, polymers or alternate composite material in conjunction with rebar or not. Reinforced concrete may also be permanently stressed (concrete in compression, reinforcement in tension), so as to improve the behaviour of the final structure under working loads. In the United States, the most common methods of doing this are known as pre-tensioning and post-tensioning.

For a strong, ductile and durable construction the reinforcement needs to have the following properties at least:

High relative strength

High toleration of tensile strain

Good bond to the concrete, irrespective of pH, moisture, and similar factors

Thermal compatibility, not causing unacceptable stresses (such as expansion or contraction) in response to changing temperatures.

Durability in the concrete environment, irrespective of corrosion or sustained stress for example.

François Coignet was the first to use iron-reinforced concrete as a technique for constructing building structures. In 1853, Coignet built the first iron reinforced concrete structure, a four-story house at 72 rue Charles Michels in the suburbs of Paris. Coignet's descriptions of reinforcing concrete suggests that he did not do it for means of adding strength to the concrete but for keeping walls in monolithic construction from overturning. In 1854, English builder William B. Wilkinson reinforced the concrete roof and floors in the two-story house he was constructing. His positioning of the reinforcement demonstrated that, unlike his predecessors, he had knowledge of tensile stresses.

Joseph Monier, a 19th-century French gardener, was a pioneer in the development of structural, prefabricated and reinforced concrete, having been dissatisfied with the existing materials available for making durable flowerpots. He was granted a patent for reinforcing concrete flowerpots by means of mixing a wire mesh and a mortar shell. In 1877, Monier was granted another patent for a more advanced technique of reinforcing concrete columns and girders, using iron rods placed in a grid pattern. Though Monier undoubtedly knew that reinforcing concrete would improve its inner cohesion, it is not clear whether he even knew how much the tensile strength of concrete was improved by the reinforcing.

Before the 1870s, the use of concrete construction, though dating back to the Roman Empire, and having been reintroduced in the early 19th century, was not yet a proven scientific technology. Thaddeus Hyatt, published a report entitled An Account of Some Experiments with Portland-Cement-Concrete Combined with Iron as a Building Material, with Reference to Economy of Metal in Construction and for Security against Fire in the Making of Roofs, Floors, and Walking Surfaces, in which he reported his experiments on the behavior of reinforced concrete. His work played a major role in the evolution of concrete construction as a proven and studied science. Without Hyatt's work, more dangerous trial and error methods might have been depended on for the advancement in the technology.

Ernest L. Ransome, an English-born engineer, was an early innovator of reinforced concrete techniques at the end of the 19th century. Using the knowledge of reinforced concrete developed during the previous 50 years, Ransome improved nearly all the styles and techniques of the earlier inventors of reinforced concrete. Ransome's key innovation was to twist the reinforcing steel bar, thereby improving its bond with the concrete. Gaining increasing fame from his concrete constructed buildings, Ransome was able to build two of the first reinforced concrete bridges in North America. One of the first concrete buildings constructed in the United States was a private home designed by William Ward, completed in 1876. The home was particularly designed to be fireproof.

G. A. Wayss was a German civil engineer and a pioneer of the iron and steel concrete construction. In 1879, Wayss bought the German rights to Monier's patents and, in 1884, his firm, Wayss & Freytag, made the first commercial use of reinforced concrete. Up until the 1890s, Wayss and his firm greatly contributed to the advancement of Monier's system of reinforcing, established it as a well-developed scientific technology.

One of the first skyscrapers made with reinforced concrete was the 16-story Ingalls Building in Cincinnati, constructed in 1904.

The first reinforced concrete building in Southern California was the Laughlin Annex in downtown Los Angeles, constructed in 1905. In 1906, 16 building permits were reportedly issued for reinforced concrete buildings in the City of Los Angeles, including the Temple Auditorium and 8-story Hayward Hotel.

In 1906, a partial collapse of the Bixby Hotel in Long Beach killed 10 workers during construction when shoring was removed prematurely. That event spurred a scrutiny of concrete erection practices and building inspections. The structure was constructed of reinforced concrete frames with hollow clay tile ribbed flooring and hollow clay tile infill walls. That practice was strongly questioned by experts and recommendations for "pure" concrete construction were made, using reinforced concrete for the floors and walls as well as the frames.

In April 1904, Julia Morgan, an American architect and engineer, who pioneered the aesthetic use of reinforced concrete, completed her first reinforced concrete structure, El Campanil, a 72-foot (22 m) bell tower at Mills College, which is located across the bay from San Francisco. Two years later, El Campanil survived the 1906 San Francisco earthquake without any damage, which helped build her reputation and launch her prolific career. The 1906 earthquake also changed the public's initial resistance to reinforced concrete as a building material, which had been criticized for its perceived dullness. In 1908, the San Francisco Board of Supervisors changed the city's building codes to allow wider use of reinforced concrete.

In 1906, the National Association of Cement Users (NACU) published Standard No. 1 and, in 1910, the Standard Building Regulations for the Use of Reinforced Concrete.

Many different types of structures and components of structures can be built using reinforced concrete including slabs, walls, beams, columns, foundations, frames and more.

Reinforced concrete can be classified as precast or cast-in-place concrete.

Designing and implementing the most efficient floor system is key to creating optimal building structures. Small changes in the design of a floor system can have significant impact on material costs, construction schedule, ultimate strength, operating costs, occupancy levels and end use of a building.

Without reinforcement, constructing modern structures with concrete material would not be possible.

Concrete is a mixture of coarse (stone or brick chips) and fine (generally sand or crushed stone) aggregates with a paste of binder material (usually Portland cement) and water. When cement is mixed with a small amount of water, it hydrates to form microscopic opaque crystal lattices encapsulating and locking the aggregate into a rigid structure. The aggregates used for making concrete should be free from harmful substances like organic impurities, silt, clay, lignite etc. Typical concrete mixes have high resistance to compressive stresses (about 4,000 psi (28 MPa)); however, any appreciable tension ( e.g., due to bending) will break the microscopic rigid lattice, resulting in cracking and separation of the concrete. For this reason, typical non-reinforced concrete must be well supported to prevent the development of tension.

If a material with high strength in tension, such as steel, is placed in concrete, then the composite material, reinforced concrete, resists not only compression but also bending and other direct tensile actions. A composite section where the concrete resists compression and reinforcement " rebar" resists tension can be made into almost any shape and size for the construction industry.

Three physical characteristics give reinforced concrete its special properties:

1. The coefficient of thermal expansion of concrete is similar to that of steel, eliminating large internal stresses due to differences in thermal expansion or contraction.

2. When the cement paste within the concrete hardens, this conforms to the surface details of the steel, permitting any stress to be transmitted efficiently between the different materials. Usually steel bars are roughened or corrugated to further improve the bond or cohesion between the concrete and steel.

3. The alkaline chemical environment provided by the alkali reserve (KOH, NaOH) and the portlandite (calcium hydroxide) contained in the hardened cement paste causes a passivating film to form on the surface of the steel, making it much more resistant to corrosion than it would be in neutral or acidic conditions. When the cement paste is exposed to the air and meteoric water reacts with the atmospheric CO₂, portlandite and the calcium silicate hydrate (CSH) of the hardened cement paste become progressively carbonated and the high pH gradually decreases from 13.5 - 12.5 to 8.5, the pH of water in equilibrium with calcite (calcium carbonate) and the steel is no longer passivated.

The relative cross-sectional area of steel required for typical reinforced concrete is usually quite small and varies from 1% for most beams and slabs to 6% for some columns. Reinforcing bars are normally round in cross-section and vary in diameter. Reinforced concrete structures sometimes have provisions such as ventilated hollow cores to control their moisture & humidity.

Distribution of concrete (in spite of reinforcement) strength characteristics along the cross-section of vertical reinforced concrete elements is inhomogeneous.

The reinforcement in a RC structure, such as a steel bar, has to undergo the same strain or deformation as the surrounding concrete in order to prevent discontinuity, slip or separation of the two materials under load. Maintaining composite action requires transfer of load between the concrete and steel. The direct stress is transferred from the concrete to the bar interface so as to change the tensile stress in the reinforcing bar along its length. This load transfer is achieved by means of bond (anchorage) and is idealized as a continuous stress field that develops in the vicinity of the steel-concrete interface. The reasons that the two different material components concrete and steel can work together are as follows: (1) Reinforcement can be well bonded to the concrete, thus they can jointly resist external loads and deform. (2) The thermal expansion coefficients of concrete and steel are so close (1.0×10-5~1.5×10-5 for concrete and 1.2×10-5 for steel) that the thermal stress-induced damage to the bond between the two components can be prevented. (3) Concrete can protect the embedded steel from corrosion and high-temperature induced softening.

Anchorage (bond) in concrete: Codes of specifications

Because the actual bond stress varies along the length of a bar anchored in a zone of tension, current international codes of specifications use the concept of development length rather than bond stress. The main requirement for safety against bond failure is to provide a sufficient extension of the length of the bar beyond the point where the steel is required to develop its yield stress and this length must be at least equal to its development length. However, if the actual available length is inadequate for full development, special anchorages must be provided, such as cogs or hooks or mechanical end plates. The same concept applies to lap splice length mentioned in the codes where splices (overlapping) provided between two adjacent bars in order to maintain the required continuity of stress in the splice zone.

In wet and cold climates, reinforced concrete for roads, bridges, parking structures and other structures that may be exposed to deicing salt may benefit from use of corrosion-resistant reinforcement such as uncoated, low carbon/chromium (micro composite), epoxy-coated, hot dip galvanised or stainless steel rebar. Good design and a well-chosen concrete mix will provide additional protection for many applications. Uncoated, low carbon/chromium rebar looks similar to standard carbon steel rebar due to its lack of a coating; its highly corrosion-resistant features are inherent in the steel microstructure. It can be identified by the unique ASTM specified mill marking on its smooth, dark charcoal finish. Epoxy coated rebar can easily be identified by the light green colour of its epoxy coating. Hot dip galvanized rebar may be bright or dull grey depending on length of exposure, and stainless rebar exhibits a typical white metallic sheen that is readily distinguishable from carbon steel reinforcing bar. Reference ASTM standard specifications A1035/A1035M Standard Specification for Deformed and Plain Low-carbon, Chromium, Steel Bars for Concrete Reinforcement, A767 Standard Specification for Hot Dip Galvanised Reinforcing Bars, A775 Standard Specification for Epoxy Coated Steel Reinforcing Bars and A955 Standard Specification for Deformed and Plain Stainless Bars for Concrete Reinforcement.

Another, cheaper way of protecting rebars is coating them with zinc phosphate. Zinc phosphate slowly reacts with calcium cations and the hydroxyl anions present in the cement pore water and forms a stable hydroxyapatite layer.

Penetrating sealants typically must be applied some time after curing. Sealants include paint, plastic foams, films and aluminum foil, felts or fabric mats sealed with tar, and layers of bentonite clay, sometimes used to seal roadbeds.

Corrosion inhibitors, such as calcium nitrite [Ca(NO ₂) ₂], can also be added to the water mix before pouring concrete. Generally, 1-2 wt. % of [Ca(NO ₂) ₂] with respect to cement weight is needed to prevent corrosion of the rebars. The nitrite anion is a mild oxidizer that oxidizes the soluble and mobile ferrous ions (Fe ²⁺) present at the surface of the corroding steel and causes them to precipitate as an insoluble ferric hydroxide (Fe(OH) ₃). This causes the passivation of steel at the anodic oxidation sites. Nitrite is a much more active corrosion inhibitor than nitrate, which is a less powerful oxidizer of the divalent iron.

A beam bends under bending moment, resulting in a small curvature. At the outer face (tensile face) of the curvature the concrete experiences tensile stress, while at the inner face (compressive face) it experiences compressive stress.

A singly reinforced beam is one in which the concrete element is only reinforced near the tensile face and the reinforcement, called tension steel, is designed to resist the tension.

A doubly reinforced beam is the section in which besides the tensile reinforcement the concrete element is also reinforced near the compressive face to help the concrete resist compression and take stresses. The latter reinforcement is called compression steel. When the compression zone of a concrete is inadequate to resist the compressive moment (positive moment), extra reinforcement has to be provided if the architect limits the dimensions of the section.

An under-reinforced beam is one in which the tension capacity of the tensile reinforcement is smaller than the combined compression capacity of the concrete and the compression steel (under-reinforced at tensile face). When the reinforced concrete element is subject to increasing bending moment, the tension steel yields while the concrete does not reach its ultimate failure condition. As the tension steel yields and stretches, an "under-reinforced" concrete also yields in a ductile manner, exhibiting a large deformation and warning before its ultimate failure. In this case the yield stress of the steel governs the design.

An over-reinforced beam is one in which the tension capacity of the tension steel is greater than the combined compression capacity of the concrete and the compression steel (over-reinforced at tensile face). So the "over-reinforced concrete" beam fails by crushing of the compressive-zone concrete and before the tension zone steel yields, which does not provide any warning before failure as the failure is instantaneous.

A balanced-reinforced beam is one in which both the compressive and tensile zones reach yielding at the same imposed load on the beam, and the concrete will crush and the tensile steel will yield at the same time. This design criterion is however as risky as over-reinforced concrete, because failure is sudden as the concrete crushes at the same time of the tensile steel yields, which gives a very little warning of distress in tension failure.

Steel-reinforced concrete moment-carrying elements should normally be designed to be under-reinforced so that users of the structure will receive warning of impending collapse.

The characteristic strength is the strength of a material where less than 5% of the specimen shows lower strength.

The design strength or nominal strength is the strength of a material, including a material-safety factor. The value of the safety factor generally ranges from 0.75 to 0.85 in Permissible stress design.

The ultimate limit state is the theoretical failure point with a certain probability. It is stated under factored loads and factored resistances.

Reinforced concrete structures are normally designed according to rules and regulations or recommendation of a code such as ACI-318, CEB, Eurocode 2 or the like. WSD, USD or LRFD methods are used in design of RC structural members. Analysis and design of RC members can be carried out by using linear or non-linear approaches. When applying safety factors, building codes normally propose linear approaches, but for some cases non-linear approaches. To see the examples of a non-linear numerical simulation and calculation visit the references:

Prestressing concrete is a technique that greatly increases the load-bearing strength of concrete beams. The reinforcing steel in the bottom part of the beam, which will be subjected to tensile forces when in service, is placed in tension before the concrete is poured around it. Once the concrete has hardened, the tension on the reinforcing steel is released, placing a built-in compressive force on the concrete. When loads are applied, the reinforcing steel takes on more stress and the compressive force in the concrete is reduced, but does not become a tensile force. Since the concrete is always under compression, it is less subject to cracking and failure.

Reinforced concrete can fail due to inadequate strength, leading to mechanical failure, or due to a reduction in its durability. Corrosion and freeze/thaw cycles may damage poorly designed or constructed reinforced concrete. When rebar corrodes, the oxidation products ( rust) expand and tends to flake, cracking the concrete and unbonding the rebar from the concrete. Typical mechanisms leading to durability problems are discussed below.

Cracking of the concrete section is nearly impossible to prevent; however, the size and location of cracks can be limited and controlled by appropriate reinforcement, control joints, curing methodology and concrete mix design. Cracking can allow moisture to penetrate and corrode the reinforcement. This is a serviceability failure in limit state design. Cracking is normally the result of an inadequate quantity of rebar, or rebar spaced at too great a distance. The concrete then cracks either under excess loading, or due to internal effects such as early thermal shrinkage while it cures.

Ultimate failure leading to collapse can be caused by crushing the concrete, which occurs when compressive stresses exceed its strength, by yielding or failure of the rebar when bending or shear stresses exceed the strength of the reinforcement, or by bond failure between the concrete and the rebar.

It was once common for calcium chloride to be used as an admixture to promote rapid set-up of the concrete. It was also mistakenly believed that it would prevent freezing. However, this practice fell into disfavor once the deleterious effects of chlorides became known. It should be avoided whenever possible.

Another important source of chloride ions is sea water. Sea water contains by weight approximately 3.5% salts. These salts include sodium chloride, magnesium sulfate, calcium sulfate, and bicarbonates. In water these salts dissociate in free ions (Na⁺, Mg ²⁺, Cl −, SO ₄ 2−, HCO ₃−) and migrate with the water into the capillaries of the concrete. Chloride ions, which make up about 50% of these ions, are particularly aggressive as a cause of corrosion of carbon steel reinforcement bars.

In the 1960s and 1970s it was also relatively common for magnesite, a chloride rich carbonate mineral, to be used as a floor-topping material. This was done principally as a levelling and sound attenuating layer. However it is now known that when these materials come into contact with moisture they produce a weak solution of hydrochloric acid due to the presence of chlorides in the magnesite. Over a period of time (typically decades), the solution causes corrosion of the embedded rebars. This was most commonly found in wet areas or areas repeatedly exposed to moisture.

This a reaction of amorphous silica ( chalcedony, chert, siliceous limestone) sometimes present in the aggregates with the hydroxyl ions (OH −) from the cement pore solution. Poorly crystallized silica (SiO ₂) dissolves and dissociates at high pH (12.5 - 13.5) in alkaline water. The soluble dissociated silicic acid reacts in the porewater with the calcium hydroxide ( portlandite) present in the cement paste to form an expansive calcium silicate hydrate (CSH). The alkali-silica reaction (ASR) causes localised swelling responsible for tensile stress and cracking. The conditions required for alkali silica reaction are threefold: (1) aggregate containing an alkali-reactive constituent (amorphous silica), (2) sufficient availability of hydroxyl ions (OH −), and (3) sufficient moisture, above 75% relative humidity (RH) within the concrete. This phenomenon is sometimes popularly referred to as " concrete cancer". This reaction occurs independently of the presence of rebars; massive concrete structures such as dams can be affected.

Resistant to weak acids and especially sulfates, this cement cures quickly and has very high durability and strength. It was frequently used after World War II to make precast concrete objects. However, it can lose strength with heat or time (conversion), especially when not properly cured. After the collapse of three roofs made of prestressed concrete beams using high alumina cement, this cement was banned in the UK in 1976. Subsequent inquiries into the matter showed that the beams were improperly manufactured, but the ban remained.

Sulfates (SO ₄) in the soil or in groundwater, in sufficient concentration, can react with the Portland cement in concrete causing the formation of expansive products, e.g., ettringite or thaumasite, which can lead to early failure of the structure. The most typical attack of this type is on concrete slabs and foundation walls at grades where the sulfate ion, via alternate wetting and drying, can increase in concentration. As the concentration increases, the attack on the Portland cement can begin. For buried structures such as pipe, this type of attack is much rarer, especially in the eastern United States. The sulfate ion concentration increases much slower in the soil mass and is especially dependent upon the initial amount of sulfates in the native soil. A chemical analysis of soil borings to check for the presence of sulfates should be undertaken during the design phase of any project involving concrete in contact with the native soil. If the concentrations are found to be aggressive, various protective coatings can be applied. Also, in the US ASTM C150 Type 5 Portland cement can be used in the mix. This type of cement is designed to be particularly resistant to a sulfate attack.

In steel plate construction, stringers join parallel steel plates. The plate assemblies are fabricated off site, and welded together on-site to form steel walls connected by stringers. The walls become the form into which concrete is poured. Steel plate construction speeds reinforced concrete construction by cutting out the time-consuming on-site manual steps of tying rebar and building forms. The method results in excellent strength because the steel is on the outside, where tensile forces are often greatest.

Fiber reinforcement is mainly used in shotcrete, but can also be used in normal concrete. Fiber-reinforced normal concrete is mostly used for on-ground floors and pavements, but can also be considered for a wide range of construction parts (beams, pillars, foundations, etc.), either alone or with hand-tied rebars.

Concrete reinforced with fibers (which are usually steel, glass, plastic fibers) or Cellulose polymer fibre is less expensive than hand-tied rebar.[citation needed ] The shape, dimension, and length of the fiber are important. A thin and short fiber, for example short, hair-shaped glass fiber, is only effective during the first hours after pouring the concrete (its function is to reduce cracking while the concrete is stiffening), but it will not increase the concrete tensile strength. A normal-size fiber for European shotcrete (1 mm diameter, 45 mm length-steel or plastic) will increase the concrete's tensile strength. Fiber reinforcement is most often used to supplement or partially replace primary rebar, and in some cases it can be designed to fully replace rebar.

Steel is the strongest commonly available fiber,[citation needed ] and comes in different lengths (30 to 80 mm in Europe) and shapes (end-hooks). Steel fibers can only be used on surfaces that can tolerate or avoid corrosion and rust stains. In some cases, a steel-fiber surface is faced with other materials.

The premium fibers are graphite-reinforced plastic fibers, which are nearly as strong as steel, lighter in weight, and corrosion-proof.[citation needed ] Some experiments have had promising early results with carbon nanotubes, but the material is still far too expensive for any building.[citation needed ]

There is considerable overlap between the subjects of non-steel reinforcement and fiber-reinforcement of concrete. The introduction of non-steel reinforcement of concrete is relatively recent; it takes two major forms: non-metallic rebar rods, and non-steel (usually also non-metallic) fibres incorporated into the cement matrix. For example, there is increasing interest in glass fiber reinforced concrete (GFRC) and in various applications of polymer fibres incorporated into concrete. Although currently there is not much suggestion that such materials will replace metal rebar, some of them have major advantages in specific applications, and there also are new applications in which metal rebar simply is not an option. However, the design and application of non-steel reinforcing is fraught with challenges. For one thing, concrete is a highly alkaline environment, in which many materials, including most kinds of glass, have a poor service life. Also, the behaviour of such reinforcing materials differs from the behaviour of metals, for instance in terms of shear strength, creep and elasticity.

Fibre-reinforced plastic/polymer (FRP) and glass-reinforced plastic (GRP) consist of fibres of polymer, glass, carbon, aramid or other polymers or high-strength fibres set in a resin matrix to form a rebar rod, or grid, or fibres. These rebars are installed in much the same manner as steel rebars. The cost is higher but, suitably applied, the structures have advantages, in particular a dramatic reduction in problems related to corrosion, either by intrinsic concrete alkalinity or by external corrosive fluids that might penetrate the concrete. These structures can be significantly lighter and usually have a longer service life. The cost of these materials has dropped dramatically since their widespread adoption in the aerospace industry and by the military.

In particular, FRP rods are useful for structures where the presence of steel would not be acceptable. For example, MRI machines have huge magnets, and accordingly require non-magnetic buildings. Again, toll booths that read radio tags need reinforced concrete that is transparent to radio waves. Also, where the design life of the concrete structure is more important than its initial costs, non-steel reinforcing often has its advantages where corrosion of reinforcing steel is a major cause of failure. In such situations corrosion-proof reinforcing can extend a structure's life substantially, for example in the intertidal zone. FRP rods may also be useful in situations where it is likely that the concrete structure may be compromised in future years, for example the edges of balconies when balustrades are replaced, and bathroom floors in multi-story construction where the service life of the floor structure is likely to be many times the service life of the waterproofing building membrane.

Plastic reinforcement often is stronger, or at least has a better strength to weight ratio than reinforcing steels. Also, because it resists corrosion, it does not need a protective concrete cover as thick as steel reinforcement does (typically 30 to 50 mm or more). FRP-reinforced structures therefore can be lighter and last longer. Accordingly, for some applications the whole-life cost will be price-competitive with steel-reinforced concrete.

The material properties of FRP or GRP bars differ markedly from steel, so there are differences in the design considerations. FRP or GRP bars have relatively higher tensile strength but lower stiffness, so that deflections are likely to be higher than for equivalent steel-reinforced units. Structures with internal FRP reinforcement typically have an elastic deformability comparable to the plastic deformability (ductility) of steel reinforced structures. Failure in either case is more likely to occur by compression of the concrete than by rupture of the reinforcement. Deflection is always a major design consideration for reinforced concrete. Deflection limits are set to ensure that crack widths in steel-reinforced concrete are controlled to prevent water, air or other aggressive substances reaching the steel and causing corrosion. For FRP-reinforced concrete, aesthetics and possibly water-tightness will be the limiting criteria for crack width control. FRP rods also have relatively lower compressive strengths than steel rebar, and accordingly require different design approaches for reinforced concrete columns.

One drawback to the use of FRP reinforcement is their limited fire resistance. Where fire safety is a consideration, structures employing FRP have to maintain their strength and the anchoring of the forces at temperatures to be expected in the event of fire. For purposes of fireproofing, an adequate thickness of cement concrete cover or protective cladding is necessary. The addition of 1 kg/m ³ of polypropylene fibers to concrete has been shown to reduce spalling during a simulated fire. (The improvement is thought to be due to the formation of pathways out of the bulk of the concrete, allowing steam pressure to dissipate.)

Another problem is the effectiveness of shear reinforcement. FRP rebar stirrups formed by bending before hardening generally perform relatively poorly in comparison to steel stirrups or to structures with straight fibres. When strained, the zone between the straight and curved regions are subject to strong bending, shear, and longitudinal stresses. Special design techniques are necessary to deal with such problems.

There is growing interest in applying external reinforcement to existing structures using advanced materials such as composite (fiberglass, basalt, carbon) rebar, which can impart exceptional strength. Worldwide, there are a number of brands of composite rebar recognized by different countries, such as Aslan, DACOT, V-rod, and ComBar. The number of projects using composite rebar increases day by day around the world, in countries ranging from USA, Russia, and South Korea to Germany.

Threlfall A., et al. Reynolds's Reinforced Concrete Designer's Handbook - 11th ed. ISBN 978-0-419-25830-8.

Newby F., Early Reinforced Concrete, Ashgate Variorum, 2001, ISBN 978-0-86078-760-0.

Kim, S., Surek, J and J. Baker-Jarvis. "Electromagnetic Metrology on Concrete and Corrosion." Journal of Research of the National Institute of Standards and Technology, Vol. 116, No. 3 (May-June 2011): 655-669.

Daniel R., Formwork UK "Concrete frame structures.".

Corrosion of reinforcement in concrete construction. C. L. Page, P. B. Bamforth, J. W. Figg, International Symposium on Corrosion of Reinforcement in Concrete Construction. Cambridge: Royal Society of Chemistry, Information Services. 1996. ISBN 0-85404-731-X. OCLC 35233292.

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Reinforced concrete Type Composite material Tensile strength (σt) Stronger than concrete Reinforced concrete ( RC), also called reinforced cement concrete ( RCC), is a composite material in which concrete's relatively low tensile strength and ductility are compensated for by the inclusion of reinforcement having higher tensile strength or ductility.

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Many state and federal transportation projects in the United States require precast concrete suppliers to be certified by either the Architectural Precast Association (APA), National Precast Concrete Association (NPCA) or Precast Prestressed Concrete Institute (PCI).

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Also found in: Thesaurus, Medical, Legal, Financial, Acronyms, Idioms, Encyclopedia, Wikipedia.
Related to shore: shore up, Shore hardness

shore 1
(shôr)
n.

1. The land along the edge of an ocean, sea, lake, or river; a coast.

2. often shores Land; country: far from our native shores.

3. Land as opposed to water: a sailor with an assignment on shore.

[Middle English shore, from Old English scora; see sker- ¹ in the Appendix of Indo-European roots.]

shore 2
(shôr)

tr.v. shored, shor·ing, shores

To support by or as if by a prop: shored up the sagging floors; shored up the peace initiative.

n.

A beam or timber propped against a structure to provide support.

[Middle English shoren, from shore, prop, probably from Middle Low German schōre, barrier, or Middle Dutch scōre, prop.]

shore 3
(shôr)

v. Archaic

A past tense of shear.

shore
(ʃɔː)
n

1. (Physical Geography) the land along the edge of a sea, lake, or wide river.

2. (Physical Geography)

a. land, as opposed to water (esp in the phrase on shore)

b. ( as modifier): shore duty.

3. (Law) law the tract of coastland lying between the ordinary marks of high and low water

4. ( often plural) a country: his native shores.

vb

(Nautical Terms) ( tr) to move or drag (a boat) onto a shore

[C14: probably from Middle Low German, Middle Dutch schōre; compare Old High German scorra cliff; see shear]

shore
(ʃɔː)
n

(Building) a prop, post, or beam used to support a wall, building, ship in dry dock, etc

vb

(often foll by: up) to prop or make safe with or as if with a shore

[C15: from Middle Dutch schōre; related to Old Norse skortha prop]

shore
(ʃɔː)
vb

Austral and NZ a past tense of shear

shore¹
(ʃɔr, ʃoʊr)

n.

1. the land along the edge of a sea, lake, broad river, etc.

2. some particular country: my native shore.

3. land, as opposed to sea or water: a marine serving on shore.

[before 1000; Middle English schore, Old English scora, c. Middle Dutch, Middle Low German schore]

shore²
(ʃɔr, ʃoʊr)

n., v. shored, shor*ing. n.

1. a supporting post or beam, esp. one propped against the side of a building, a ship in drydock, etc.; prop; strut.

v.t.

2. to support by or as if by a shore or shores; prop (usu. fol. by up).

beach
– shore – coast
1. 'beach'
A beach is an area along the edge of a sea, lake, or wide river that is covered with sand or small stones. You can relax or play on a beach, or use it as a place to swim from.

He walked along the beach.

Children were building sandcastles on the beach.

2. 'shore'
Shore is a more general word for the land along the edge of a sea, lake, or wide river.

He swam towards the shore.

3. 'coast'
The coast is the border between the land and the sea, or the part of a country that is next to the sea.

We stayed in a small village on the west coast of Scotland.

There are industrial cities along the coast.

shore

Past participle: shored
Gerund: shoring

Thesaurus Antonyms Related Words Synonyms Legend:

Noun 1.
shore - the land along the edge of a body of water

beach - an area of sand sloping down to the water of a sea or lake

lake - a body of (usually fresh) water surrounded by land

ocean - a large body of water constituting a principal part of the hydrosphere

river - a large natural stream of water (larger than a creek); "the river was navigable for 50 miles"

shoreline - a boundary line between land and water

strand - a poetic term for a shore (as the area periodically covered and uncovered by the tides)

2.
shore - a beam or timber that is propped against a structure to provide support

beam - long thick piece of wood or metal or concrete, etc., used in construction

Verb 1.
shore - serve as a shore to; "The river was shored by trees"

2.
shore - arrive on shore; "The ship landed in Pearl Harbor"

arrive, come, get - reach a destination; arrive by movement or progress; "She arrived home at 7 o'clock"; "She didn't get to Chicago until after midnight"

3.
shore - support by placing against something solid or rigid; "shore and buttress an old building"

hold up, support, sustain, hold - be the physical support of; carry the weight of; "The beam holds up the roof"; "He supported me with one hand while I balanced on the beam"; "What's holding that mirror?"

bolster - prop up with a pillow or bolster

shore

shore
noun

A means or device that keeps something erect, stable, or secure:

shore

[ˈʃɔː r]

notre shores npl (= country) our shores → pays m

vt sep

[+ building, tunnel, structure] → étayer

shore

:

shoreline

n → Wasserlinie f, → Uferlinie f

shore pass

n (Naut) → Landurlaubsschein m

shore patrol

n (US) → Küstenstreife f, → Küstenpatrouille f (der US-Marine)

shore

¹

shore

²

shore
(ʃoː) noun

land bordering on the sea or on any large area of water. a walk along the shore; When the ship reached Gibraltar the passengers were allowed on shore.

shore
→ سَاحِل břeh kyst Küste όχθη ranta orilla obala rivage 岸 바닷가 riva kust kust ชายฝั่ง kyst brzeg bờ costa берег kıyı 岸

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References in classic literature?

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Define shore. shore synonyms, shore pronunciation, shore translation, English dictionary definition of shore. n. 1. The land along the edge of an ocean, sea, lake, or river; a coast. 2. often shores Land; country: far from our native shores. 3. Land as opposed to...

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concrete that has metal bars inside of it to make it stronger See the full definition...

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Ponding is the (typically) unwanted pooling of water, typically on a flat roof or roadway. Ponding water accelerates the deterioration of many materials, including seam adhesives in single-ply roof systems, steel equipment supports, and particularly roofing asphalt.

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Also found in: Encyclopedia, Wikipedia.

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Also found in: Encyclopedia, Wikipedia. Want to thank TFD for its existence? Tell a friend about us, add a link to this page, or visit the webmaster's page for free fun content. Link to this page:

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What is occupant load? definition and meaning

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Definition of occupant load: The maximum number of persons in an area at a given peak period.

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EVstudio, Architect Engineer Denver Evergreen Colorado, Austin Texas Architect

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One of the first steps in any building project is evaluation of the appropriate occupancy group. This drives building size, building height, construction type, exiting and fire separations.

Residential Group R is the occupancy group used for buildings that include sleeping rooms and are not insititutional and are not generally regulated by the Interntaionl Residential Code. The IRC typically regulates single family homes and duplexes, any structure with more than two units is in the IBC. There are four different occupancy groups within R.

The first occupancy group is R-1. This group is for transient uses like hotels, motels and boarding houses.

The next group is R-2. R-2 is the group we see most often and it for residences where occupants are primarily permanent. This includes apartments, dormitories, fraternities and sororities. It also includes vacation timeshares (again with more than two units) and convents and monasteries. Congregate living facilites with 16 or fewer occupants go into group R-3.

R-3 is something of a catchall group for permanent occupancies that aren't R-1, R-2, R-4 or I. These include buildings that are in the IBC but have no more than two units. Adult facilities and child care facilities that provide accomodation for five or less people less than 24 hours a day are R-3. Where these facilities are in a single family home they must comply with the IRC.

R-4 is for residential care/assisted living facilities including more than five and not more than 16 occupants. Generally it is very similar to R-3′s requirements.

Tagged as: Apartment, Architect, Assisted Living, Hotel, Motel, Residential

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Residential Occupancy Group as Defined in the International Building Code

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One of the first steps in any building project is evaluation of the appropriate occupancy group. This drives building size, building height, construction type, exiting and fire separations. Residential Group R is the occupancy group used for buildings that include

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Learn about this topic in these articles:

use in construction

In architecture: Nonbearing wall
Excluding the independent garden variety, the nonbearing wall appears only where loads are carried by other members, as in heavy timber and other skeletal structures. Modern steel and reinforced-concrete frames require exterior walls only for shelter and sometimes dispense with them on the...
Read More

In construction: Use of steel and other metals
...the glass curtain wall, a non-load-bearing "skin" attached to the exterior structural components of the building. The earliest all-glass curtain wall, which was only on a single street facade, was that of the Hallidie Building (1918) in San Francisco. The first multistory structure with a full glass curtain wall was...
Read More

use of bricks

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Other articles where non-load-bearing wall is discussed: architecture: Nonbearing wall: Excluding the independent garden variety, the nonbearing wall appears only where loads are carried by other members, as in heavy timber and other skeletal structures. Modern steel and reinforced-concrete frames require exterior walls only for shelter and sometimes dispense with them on the...

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A simply supported beam is a type of beam that has pinned support at one end and roller support at the other end.

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Shear Force and Bending Moment Diagrams - Wikiversity

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Below, a force of 10N is exerted at point A on a beam. This is an external force. However, because the beam is a rigid structure, the force will be transferred internally all along the beam. This internal force is known as a shear force.

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Talk:Shear Force and Bending Moment Diagrams - Wikiversity

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The explanation provided here with simple and easy to understand figures are absolutely brilliant. Looking forward to your continuation, sir. Please do go ahead sir. Your article has conveyed the ideas way easily than when I tried even harder to understand what my sir was trying to explain, by complicating it in class.

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Shallow foundations are constructed where soil layer at shallow depth (upto 1.5m) is able to support the structural loads. The depth of shallow foundations are generally less than its width.

What are different Types of Shallow Foundations?
The different types of shallow foundation are:

Strip footing

Spread or isolated footing

Combined footing Strap or cantilever footing

Mat or raft Foundation.

1. Strip Footing:

A strip footing is provided for a load-bearing wall. A strip footing is also provided for a row of columns which are so closely spaced that their spread footings overlap or nearly touch each other. In such a case, it is more economical to provide a strip footing than to provide a number of spread footings in one line. A strip footing is also known as continuous footing.

2. Spread or Isolated Footing:

A spread footing (or isolated or pad) footing is provided to support an individual column. A spread footing is circular, square or rectangular slab of uniform thickness. Sometimes, it is stepped or haunched to spread the load over a large area.

3. Combined Footing:

A combined footing supports two columns. It is used when the two columns are so close to each other that their individual footings would overlap. A combined footing is also provided when the property line is so close to one column that a spread footing would be eccentrically loaded when kept entirely within the property line. By combining it with that of an interior column, the load is evenly distributed. A combined footing may be rectangular or trapezoidal in plan.

4. Strap or Cantilever footing:

A strap (or cantilever) footing consists of two isolated footings connected with a structural strap or a lever. The strap connects the two footings such that they behave as one unit. The strap is designed as a rigid beam. The individual footings are so designed that their combined line of action passes through the resultant of the total load. a strap footing is more economical than a combined footing when the allowable soil pressure is relatively high and the distance between the columns is large.

5. Mat or Raft Foundations:

A mat or raft foundation is a large slab supporting a number of columns and walls under the entire structure or a large part of the structure. A mat is required when the allowable soil pressure is low or where the columns and walls are so close that individual footings would overlap or nearly touch each other.

Mat foundations are useful in reducing the differential settlements on non-homogeneous soils or where there is a large variation in the loads on individual columns.

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Shallow foundations are constructed where soil layer at shallow depth (upto 1.5m) is able to support the structural loads. The depth of shallow foundations are generally less than its width. The different types of shallow foundation are: Strip footing Spread or isolated footing Combined footing Strap or cantilever footing Mat or raft Foundation.

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serviceability refers to the conditions under which a building is still considered useful.

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PCI Express Provides Enterprise Reliability

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RAS Key Aspects of Power Systems Reliability

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Reliability, availability and serviceability - Wikipedia

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Reliability, availability and serviceability ( RAS) is a computer hardware engineering term involving reliability engineering, high availability, and serviceability design. The phrase was originally used by International Business Machines ( IBM) as a term to describe the robustness of their mainframe computers.

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Seismic load is one of the basic concepts of earthquake engineering which means application of an earthquake-generated agitation to a building structure or its model.

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Introduction

This resource page provides an introduction to the concepts and principles of seismic design, including strategies for designing earthquake-resistant buildings to ensure the health, safety, and security of building occupants and assets.

The essence of successful seismic design is three-fold. First, the design team must take a multi-hazard approach towards design that accounts for the potential impacts of seismic forces as well as all the major hazards to which an area is vulnerable. Second, performance-based requirements, which may exceed the minimum life safety requirements of current seismic codes, must be established to respond appropriately to the threats and risks posed by natural hazards on the building's mission and occupants. Third, and as important as the others, because earthquake forces are dynamic and each building responds according to its own design complexity, it is essential that the design team work collaboratively and have a common understanding of the terms and methods used in the seismic design process.

In addition, as a general rule, buildings designed to resist earthquakes should also resist blast (terrorism) or wind, suffering less damage. For example, were the Oklahoma Federal Building designed to seismic design standards, the damage caused by the blast would have been much less (refer to MAT Report FEMA 277). For more information, see WBDG Designing Buildings to Resist Explosive Threats section on Seismic vs. Blast Protection.

Description

About half of the states and territories in the United States-more than 109 million people and 4.3 million businesses-and most of the other populous regions of the earth are exposed to risks from seismic hazards. In the U.S. alone, the average direct cost of earthquake damage is estimated at $1 billion/year while indirect business losses are estimated to exceed $2 billion/year.

A. Origin and Measurement of Earthquakes

Plate Tectonics, the Cause of Earthquakes

Earthquakes are the shaking, rolling, or sudden shock of the earth's surface. Basically, the Earth's crust consists of a series of "plates" floating over the interior, continually moving (at 2 to 130 millimeters per year), spreading from the center, sinking at the edges, and being regenerated. Friction caused by plates colliding, extending, or subducting (one plate slides under the other) builds up stresses that, when released, causes an earthquake to radiate through the crust in a complex wave motion, producing ground failure (in the form of surface faulting [a split in the ground], landslides, liquefaction, or subsidence), or tsunami. This, in turn, can cause anywhere from minor damage to total devastation of the built environment near where the earthquake occurred.

Measuring Seismic Forces

In order to characterize or measure the effect of an earthquake on the ground (a.k.a. ground motion), the following definitions are commonly used:

Acceleration is the rate of change of speed, measured in "g"s at 980 cm/sec² or 1.00 g.
For example,

0.001g or 1 cm/sec² is perceptible by people

0.02 g or 20 cm/sec² causes people to lose their balance

0.50g is very high but buildings can survive it if the duration is short and if the mass and configuration has enough damping

Velocity (or speed) is the rate of change of position, measured in centimeters per second.

Displacement is the distance from the point of rest, measured in centimeters.

Duration is the length of time the shock cycles persists.

Magnitude is the "size" of the earthquake, measured by the Richter scale, which ranges from 1-10. The Richter scale is based on the maximum amplitude of certain seismic waves, and seismologists estimate that each unit of the Richter scale is a 31 times increase of energy. Moment Magnitude Scale is a recent measure that is becoming more frequently used.

If the level of acceleration is combined with duration, the power of destruction is defined. Usually, the longer the duration, the less acceleration the building can endure. A building can withstand very high acceleration for a very short duration in proportion with damping measures incorporated in the structure.

Intensity is the amount of damage the earthquake causes locally, which can be characterized by the 12 level Modified Mercalli Scale (MM) where each level designates a certain amount of destruction correlated to ground acceleration. Earthquake damage will vary depending on distance from origin (or epicenter), local soil conditions, and the type of construction.

B. Effects of Earthquakes on Buildings

Seismic Terminology (For definitions of terms used in this resource page, see Glossary of Seismic Terminology )

The aforementioned seismic measures are used to calculate forces that earthquakes impose on buildings. Ground shaking (pushing back and forth, sideways, up and down) generates internal forces within buildings called the Inertial Force (FInertial), which in turn causes most seismic damage.

= Mass (M) X Acceleration (A).

The greater the mass (weight of the building), the greater the internal inertial forces generated. Lightweight construction with less mass is typically an advantage in seismic design. Greater mass generates greater lateral forces, thereby increasing the possibility of columns being displaced, out of plumb, and/or buckling under vertical load (P delta Effect).

Earthquakes generate waves that may be slow and long, or short and abrupt. The length of a full cycle in seconds is the Period of the wave and is the inverse of the Frequency. All objects, including buildings, have a natural or fundamental period at which they vibrate if jolted by a shock. The natural period is a primary consideration for seismic design, although other aspects of the building design may also contribute to a lesser degree to the mitigation measures. If the period of the shock wave and the natural period of the building coincide, then the building will "resonate" and its vibration will increase or "amplify" several times.

The soil also has a period varying between 0.4 and 1.5 sec., very soft soil being 2.0 sec. Soft soils generally have a tendency to increase shaking as much as 2 to 6 times as compared to rock. Also, the period of the soil coinciding with the natural period of the building can greatly amplify acceleration of the building and is therefore a design consideration.

Seismic Design Factors

The following factors affect and are affected by the design of the building. It is important that the design team understands these factors and deal with them prudently in the design phase.

Torsion: Objects and buildings have a center of mass, a point by which the object (building) can be balanced without rotation occurring. If the mass is uniformly distributed then the geometric center of the floor and the center of mass may coincide. Uneven mass distribution will position the center of mass outside of the geometric center causing "torsion" generating stress concentrations. A certain amount of torsion is unavoidable in every building design. Symmetrical arrangement of masses, however, will result in balanced stiffness against either direction and keep torsion within a manageable range.

Damping: Buildings in general are poor resonators to dynamic shock and dissipate vibration by absorbing it. Damping is a rate at which natural vibration is absorbed.

Ductility: Ductility is the characteristic of a material (such as steel) to bend, flex, or move, but fails only after considerable deformation has occurred. Non-ductile materials (such as poorly reinforced concrete) fail abruptly by crumbling. Good ductility can be achieved with carefully detailed joints.

Strength and Stiffness: Strength is a property of a material to resist and bear applied forces within a safe limit. Stiffness of a material is a degree of resistance to deflection or drift (drift being a horizontal story-to-story relative displacement).

Building Configuration: This term defines a building's size and shape, and structural and nonstructural elements. Building configuration determines the way seismic forces are distributed within the structure, their relative magnitude, and problematic design concerns.

Regular Configuration buildings have Shear Walls or Moment-Resistant Frames or Braced Frames and generally have:

Low Height to Base Ratios

Equal Floor Heights

Symmetrical Plans

Uniform Sections and Elevations

Maximum Torsional Resistance

Short Spans and Redundancy

Direct Load Paths

Irregular Configuration buildings are those that differ from the "Regular" definition and have problematic stress concentrations and torsion.

Soft First Story is a discontinuity of strength and stiffness for lateral load at the ground level.

Discontinuous Shear Walls do not line up consistently one upon the other causing "soft" levels.

Variation in Perimeter Strength and Stiffness such as an open front on the ground level usually causes eccentricity or torsion.

Reentrant Corners in the shapes of H, L, T, U, +, or [] develop stress concentration at the reentrant corner and torsion. Seismic designs should adequately separate reentrant corners or strengthen them.

Knowledge of the building's period, torsion, damping, ductility, strength, stiffness, and configuration can help one determine the most appropriate seismic design devices and mitigation strategies to employ.

C. Seismic Design Strategies and Devices

Diaphragms: Floors and roofs can be used as rigid horizontal planes, or diaphragms, to transfer lateral forces to vertical resisting elements such as walls or frames.

Shear Walls: Strategically located stiffened walls are shear walls and are capable of transferring lateral forces from floors and roofs to the foundation.

Braced Frames: Vertical frames that transfer lateral loads from floors and roofs to foundations. Like shear walls, Braced Frames are designed to take lateral loads but are used where shear walls are impractical.

Moment-Resistant Frames: Column/beam joints in moment-resistant frames are designed to take both shear and bending thereby eliminating the space limitations of solid shear walls or braced frames. The column/beam joints are carefully designed to be stiff yet to allow some deformation for energy dissipation taking advantage of the ductility of steel (reinforced concrete can be designed as a Moment-Resistant Frame as well).

Energy-Dissipating Devices: Making the building structure more resistive will increase shaking which may damage the contents or the function of the building. Energy-Dissipating Devices are used to minimize shaking. Energy will dissipate if ductile materials deform in a controlled way. An example is Eccentric Bracing whereby the controlled deformation of framing members dissipates energy. However, this will not eliminate or reduce damage to building contents. A more direct solution is the use of energy dissipating devices that function like shock absorbers in a moving car. The period of the building will be lengthened and the building will "ride out" the shaking within a tolerable range.

Base Isolation: This seismic design strategy involves separating the building from the foundation and acts to absorb shock. As the ground moves, the building moves at a slower pace because the isolators dissipate a large part of the shock. The building must be designed to act as a unit, or "rigid box", of appropriate height (to avoid overturning) and have flexible utility connections to accommodate movement at its base. Base Isolation is easiest to incorporate in the design of new construction. Existing buildings may require alterations to be made more rigid to move as a unit with foundations separated from the superstructure to insert the Base Isolators. Additional space (a "moat") must be provided for horizontal displacement (the whole building will move back and forth a whole foot or more). Base Isolation retrofit is a costly operation that is most commonly appropriate in high asset value facilities and may require partial or the full removal of building occupants during installation.

The materials used for Elastomeric Isolators are natural rubber, high-damping rubber, or another elastomer in combination with metal parts. Frictive Isolators are also used and are made primarily of metal parts.

Tall buildings cannot be base-isolated or they would overturn. Being very flexible compared to low-rise buildings, their horizontal displacement needs to be controlled. This can be achieved by the use of Dampers, which absorb a good part of the energy making the displacement tolerable. Retrofitting existing buildings is often easier with dampers than with base isolators, especially if the application is external or does not interfere with the occupants.

There are many types of dampers used to mitigate seismic effects, including:

Hysteric dampers utilize the deformation of metal parts

Visco-elastic dampers stretch an elastomer in combination with metal parts

Frictive dampers use metal or other surfaces in friction

Viscous dampers compress a fluid in a piston-like device

Hybrid dampers utilize the combination of elastomeric and metal or other parts

D. Nonstructural Damage Control

All items, which are not part of the structural system, are considered as "nonstructural", and include such building elements as:

Exterior cladding and curtain walls

Parapet walls

Canopies and marquees

Chimneys and stacks

Partitions, doors, windows

Suspended ceilings

Routes of exit and entrance

Mechanical, Plumbing, Electrical and Communications equipment

Elevators

Furniture and equipment

These items must be stabilized with bracing to prevent their damage or total destruction. Building machinery and equipment can be outfitted with seismic isolating devices, which are modified versions of the standard Vibration Isolators.

Loss arising from nonstructural damage can be a multiple of the structural losses. Loss of business and failure of entire businesses was very high in the Loma Prieta, Northridge, and Kobe earthquakes due to both structural and nonstructural seismic damages.

Application

The principles and strategies of seismic design and construction are applied in a systematic approach that matches an appropriate response to specific conditions through the following major steps:

1. Analyze Site Conditions

The location and physical properties of the site are the primary influences the entire design process. The following questions can serve as a checklist to identify seismic design objectives.

1. Where is the location of the nearest fault?

2. Are there unconsolidated natural or man-made fills present?

3. Is there a potential for landslide or liquefaction on or near the site?

4. Are there vulnerable transportation, communication, and utilities connections?

5. Are there any hazardous materials on the site to be protected?

6. Is there potential for battering by adjacent buildings?

7. Is there exposure to potential flood from tsunami, seiche, or dam failure?

Consider mission critical or business continuity threats of seismicity on adjacent sites or elsewhere in the vicinity that may render the project site inaccessible or causes the loss of utilities, threat of fire, or the release of toxic materials to the site. Conduct subsurface investigations to discover loose soils or uncontrolled fill that could increase ground motion. Hard dense soils remain more stable, while solid dense rock is the most predictable and seismically safe building base.

2. Establish Seismic Design Objectives

A performance-based approach to establishing seismic design objectives is recommended. This determines a level of predictable building behavior by responding to the maximum considered earthquake. A threat/vulnerability assessment and risk analysis can be used to define the level of performance desired for the building project. Some suggested seismic design performance goals are:

Conform to local building codes providing "Life Safety," meaning that the building may collapse eventually but not during the earthquake.

Design for repairable structural damage, required evacuation of the building, and acceptable loss of business for stipulated number of days.

Design for repairable nonstructural damage, partial or full evacuation, and acceptable loss of business for stipulated number of days due to repair.

Design for repairable structural damage, no evacuation required, and acceptable loss of business for stipulated number of days due to repair.

No structural damage, repairable nonstructural damage, no evacuation, and acceptable loss of business for stipulated number of days due to repair.

No structural or nonstructural damage, and no loss of business caused by either (excluding damage to tenants' own equipment such as file cabinets, bookshelves, furniture, office equipment etc. if not properly anchored).

Regarding the magnitude of the earthquake it may also be stipulated as "Low," "Moderate," or "Large" as another matrix of grading threat and establishing corresponding building performance goals.

3. Select/Design Appropriate Structural Systems

Seismic design objectives can greatly influence the selection of the most appropriate structural system and related building systems for the project. Some construction type options, and corresponding seismic properties, are:

Wood or timber frame (good energy absorption, light weight, framing connections are critical).

Reinforced masonry walls (good energy absorption if walls and floors are well integrated; proportion of spandrels and piers are critical to avoid cracking)

Reinforced concrete walls (good energy absorption if walls and floors well integrated; proportion of spandrels and piers are critical to avoid cracking)

Steel frame with masonry fill-in walls (good energy absorption if bay sizes are small and building plan is uniform)

Steel frame, braced (extensive bracing, detailing, and proportions are important)

Steel frame, moment-resisting (good energy absorption, connections are critical)

Steel frame, eccentrically braced (excellent energy absorption, connections are critical)

Pre-cast concrete frame (poor performer without special energy absorbing connections)

Structural and architectural detailing and construction quality control is very important to ensure ductility and natural damping and to keep damages to a limited and repairable range. The prospect of structural and nonstructural damage is not likely to be eliminated without the prudent use of energy-dissipating devices. The cost of adding energy-dissipating devices is in the range of 1-2% of the total structural cost. This is not a large number, particularly when related to the life-cycle cost of the building. Within a 30-50 year life cycle the cost is negligible.

Relevant Codes and Standards

Many building codes and governmental standards exist pertaining to design and construction for seismic hazard mitigation. As previously mentioned, building code requirements are primarily prescriptive and define seismic zones and minimum safety factors to "design to." Codes pertaining to seismic requirements may be local, state, or regional building codes or amendments and should be researched thoroughly by the design professional.

Many governmental agencies at the federal level have seismic standards, criteria, and program specialists who are involved in major building programs and can give further guidance on special requirements.

Federal Emergency Management Agency (FEMA)
Provides a number of web-based "Disaster Communities," organized around multi-hazard issues, including an Earthquake Disaster Community with major seismic related FEMA publications.

International Code Council (ICC)
ICC was established in 1994 to developing a single set of comprehensive and coordinated national model construction codes. The founders of the ICC are Building Officials and Code Administrators International, Inc. (BOCA), International Conference of Building Officials (ICBO), and Southern Building Code Congress International, Inc. (SBCCI).

National Earthquake Hazards Reduction Program (NEHRP)
FEMA's earthquake program was established in 1977, under the authority of the Earthquake Hazards Reduction Act of 1977, enacted asPublic Law 101-614. The purpose of the National Earthquake Hazards Reduction Program (NEHRP) is to reduce the risks of life and property from future earthquakes. FEMA serves as lead agency among the four primary NEHRP federal partners, responsible for planning and coordinating the Program.

Standards of Seismic Safety for Existing Federally Owned and Leased Buildings-a report of the NIST Interagency Committee on Seismic Safety in Construction (ICSSC RP 6) (NISTIR 6762)

Additional Resources

For definitions of terms used in this resource page, see Glossary of Seismic Terminology .

WBDG

Design Objectives

Functional / Operational-Ensure Occupant Safety and Health, Secure / Safe Secure / Safe-Natural Hazards Mitigation, Secure / Safe-Provide Security for Building Occupants and Assets

Systems & Specifications

Building Envelope Design Guide
Wall Systems Branch
Organizations

Websites

Federal Emergency Management Agency (FEMA) Mitigation Division-One of the features of FEMA's site is a map library, containing: GIS mapping products and data for the latest disasters, along with current and prior year disasters and custom hazard maps that can be created by entering a zip code and selecting from a variety of hazard types to help determine disaster risks in any community. In addition, the Mitigation Directorate's Flood Hazard Mapping Technical Services Division maintains and updates the National Flood Insurance Program maps.

Mitigation Clearinghouse-The Clearinghouse serves to provide a dynamic resource library, thereby improving discovery and accessibility of mitigation related literature.

Natural Hazards Center-The Natural Hazards Center, located at the University of Colorado, Boulder, Colorado, USA, is a national and international clearinghouse for information on natural hazards and human adjustments to hazards and disasters.

Seismosoft-providing the earthquake engineering community with access to powerful and state-of-the-art analytical tools since 2002.

USGS National Earthquake Information Center

Publications

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National Earthquake Hazards Reduction Program

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C. Seismic Design Strategies and Devices Diaphragms

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NIST Interagency Committee on Seismic Safety in Construction

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Base Ratios Equal Floor Heights Symmetrical Plans Uniform Sections and Elevations Maximum Torsional Resistance Short Spans and Redundancy Direct Load Paths Irregular Configuration

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Assets Systems & Specifications Building Envelope Design Guide Wall Systems Branch Organizations Websites Federal Emergency Management Agency

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Code Administrators International , Inc.

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A. Origin and Measurement of Earthquakes Plate Tectonics

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Southern Building Code Congress International , Inc.

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Flood Hazard Mapping Technical Services Division

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This resource page provides an introduction to the concepts and principles of seismic design, including strategies for designing earthquake-resistant buildings to ensure the health, safety, and security of building occupants and assets. The essence of successful seismic design is three-fold.

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a margin of security against risks.

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Overview

Modern buildings are generally considered safe and healthy working environments. However, the potential for indoor air quality problems, occupational illnesses and injuries, exposure to hazardous materials, and accidental falls beckons architects, engineers, and facility managers to design and maintain buildings and processes that ensure occupant safety and health. Notably, building designs must focus on eliminating or preventing hazards to personnel, rather than relying on personal protective equipment and administrative or process procedures to prevent mishaps.

Protecting the health, safety, and welfare (HSW) of building occupants has expanded beyond disease prevention and nuisance control to include mental as well as physical health (see Productive) and protecting the ecological health of a place (see Sustainable) through the creation of spaces that enable delight and the realization of human potential.

Therefore, the design team should apply an integrated approach, including work process analysis and hazard recognition to develop solutions that provide healthy built environments, having no undue physical stressors, as well as meeting other project requirements. In addition, consideration of HSW issues should be an integral part of all phases of a building's life cycle: planning, design, construction, operations and maintenance, renovation, and final disposal.

Provide designs that eliminate or reduce hazards in the work place to prevent mishaps and reduce reliance on personal protective equipment.

Prevent occupational injuries and illnesses.

Prevent falls from heights.

Prevent slips, trips, and falls.

Ensure electrical safety from turn-over through Operations and Maintenance. Modifications must be in conformance with life safety codes and standards and be documented.

Eliminate exposure to hazardous materials (e.g., volatile organic compounds (VOCs) and formaldehyde, and lead and asbestos in older buildings).

Provide good indoor air quality (IAQ) and adequate ventilation.

Analyze work requirements and provide ergonomic work places to prevent work-related musculoskeletal disorders (WMSD).

Perform proper building operations and maintenance.

Recommendations

Provide Designs that Eliminate or Reduce Hazards in the Work Place to Prevent Mishaps

Provide designs in accordance with good practice as well as applicable building, fire, safety, and health codes and regulations. See Standards and Code Organizations found at the end of this section.

Conduct preliminary hazard analyses and design reviews to eliminate or mitigate hazards in the work place.

Use registered design professionals and accredited safety professionals to ensure compliance with safety standards and codes.

Provide engineering controls in place rather than rely on personal protective equipment or administrative work procedures to prevent mishaps.

Integrate safety mechanisms, such as built-in anchors or tie-off points, into the building design, especially for large mechanical systems.

Design a means for safely cleaning and maintaining interior spaces and building exteriors.

Provide for receiving, storing, and handling of materials, such as combustibles, cleaning products, office supplies, and perishables.

Prevent Occupational Injuries and Illnesses

Consider work practices, employee physical requirements, and eliminating confined spaces when designing buildings and processes.

Design for safe replacement and modifications of equipment to reduce the risk of injury to operations and maintenance staff.

Comply with applicable regulatory requirements such as the Occupational Safety and Health Administration (OSHA) standards. All OSHA standards are available in the 29 Code of Federal Regulation) (1926-Construction, and 1910-General Industry).

Provide proper ventilation under all circumstances, and allow for natural lighting where possible. See High-Performance HVAC and Natural Ventilation.

Mitigate noise hazards from equipment and processes.

Designate safe locations for installation of RF equipment such as antennas on rooftop penthouses.

Prevent Falls from Heights

Provide guardrails and barriers that will prevent falls from heights in both interior and exterior spaces.

Provide fall protection for all maintenance personnel especially for roof-mounted equipment such as HVAC equipment and cooling towers.

Provide certified tie-off points for fall arrest systems.

Prevent Slips, Trips, and Falls

Provide interior and exterior floor surfaces that do not pose slip or trip hazards.

Select exterior walking surface materials that are not susceptible to changes in elevation as a result of freeze/thaw cycles.

Provide adequate illumination, both natural and artificial, for all interior and exterior areas. See Daylighting and Energy Efficient Lighting.

Comply with all regulatory and statutory requirements such as the Americans with Disabilities Act. See WBDG Accessible Branch.

Ensure Electrical Safety

Ensure compliance with the National Electrical Code (NEC) NFPA-70.

Provide adequate space for maintenance, repair, and expansion in electrical rooms and closets.

Provide adequate drainage and/or containment from areas with energized electrical equipment.

Evaluate all areas where ground fault circuit interruption (GFI) and arc fault interruption (AFI) devices may be needed.

Consider response of emergency personnel in cases of fires and natural disasters.

Label all electrical control panels and circuits.

Install non-conductive flooring at service locations for high voltage equipment.

Specify high-visibility colors for high voltage ducts and conduits.

Eliminate Exposure to Hazardous Materials

Identify, isolate, remove, or manage in place hazardous materials such as lead, asbestos, etc.

Consider use of sampling techniques for hazardous substances in all phases of the project to include planning, design, construction, and maintenance.

Consider occupant operations and materials in designing ventilation and drainage systems.

Incorporate integrated pest management (IPM) concepts and requirements into facility design and construction (e.g., use of proper door sweeps, lighting, trash compactors, etc.) and require the use of IPM be performed by qualified personnel during all phases of construction and after the facility is completed. This should include not only interior pest management, but landscape and turf pest management as well. See Sustainable O&M.

Provide adequate space for hazardous materials storage compartments and segregate hazardous materials to avoid incompatibility.

Substitute high hazardous products with those of lower toxicity/physical properties.

Provide Good Indoor Air Quality and Adequate Ventilation

Consider ventilation systems that will exceed minimum ASHRAE standards.

Recognize and provide specially designed industrial ventilation for all industrial processes to remove potential contaminants from the breathing zone.

Design separate ventilation systems for industrial and hazardous areas within a building.

Consider the use of carbon monoxide (CO) monitoring equipment if there are CO sources, such as fuel-burning equipment or garages, in the building.

Specify materials and furnishings that are low emitters of indoor air contaminants such as volatile organic compounds (VOCs). See Green Products.

Consider the indoor relative humidity in the design of the ventilation system.

Avoid interior insulation of ductwork.

Locate outside air intakes to minimize entrainment of exhaust fumes and other odors. (e.g., vehicle exhaust, grass cutting and ground maintenance activities, industrial pollutant sources, cooling tower blow-offs, and sewage ejector pits).

Ensure the integrity of the building envelope, including caulks and seals, to preclude water intrusion that may contribute to mold growth.

Prevent return air plenums/systems from entraining air from unintended spaces.

Provide air barriers at interior walls between thermally different spaces to prevent mold and mildew.

Provide Ergonomic Workplaces and Furniture to Prevent Work-Related Musculoskeletal Disorders (WMSD)

Design work places that make the job fit the person. See WBDG Functional /Operational Design Objective.

Select furnishings, chairs, and equipment that are ergonomically designed and approved for that use.

Design equipment and furnishings reflective of work practices in an effort to eliminate repetitive motions and vibrations as well as prevent strains and sprains.

Consider using worker comfort surveys in the design phase to help eliminate work-related musculoskeletal disorders.

Accept the principle that one size does not fit all employees. See Accessible-Beyond Accessibility to Universal Design.

Consider providing break areas to allow the employees to temporarily leave the work place.

Minimize lighting glare on computer monitor screens. Provide task lighting at workstations to minimize eye fatigue. See Energy Efficient Lighting.

Perform Proper Building Operations and Maintenance

Proper preventative maintenance (PM) not only improves the useful life of the systems and building structures, but it can lend to good indoor air quality and prevent "sick building" syndromes. See Sustainable O&M Practices.

Ensure all maintenance and operation documentation, especially an equipment inventory, is submitted to the building owner/operator prior to building occupancy.

Follow manufacturer recommendations for proper building operations and maintenance.

Include safety training of operator personnel as part of the construction contractor's deliverables.

Require the use of integrated pest management (IPM) for all pest management services, interior and exterior of the building.

Require building maintenance personnel to maintain the HVAC air infiltration devices and condensate water biocides appropriately.

Monitor chemical inventories to identify opportunities to substitute green products.

Consider incorporating continuous commissioning into your building maintenance program. Federal mandate for continuous commissioning are found in EPAct 2005 and EISA 2007 .

Related Issues

Health and Safety of Telecommuting Employees: In January 2000, the Department of Labor said that employers would not be held liable for health and safety violations occurring in the homes of telecommuting employees. See " Department of Labor CPL 02-00-125. The Department of Labor stated that it would not hold employers responsible for health and safety violations that occur in home workplaces other than home offices, for example, fireworks being manufactured in the home, or other activities involving the use of hazardous materials.

Contamination of HVAC Systems: Potential exposure of building occupants to molds from contaminated HVAC systems, especially during maintenance and renovation projects, remains a serious concern. Reaction to exposure can range from negligible to severe among building occupants and can frequently be very difficult to definitively identify as a causal factor for occupants' symptoms. Special care must be exercised in HVAC design, especially, to prevent excessive humidity in system components.

Fiberglass is used extensively in building construction, especially for insulation and sound attenuation in HVAC systems. Considerable concern exists regarding the potential adverse health effects of inhaling fiberglass fibers. A number of studies are currently investigating the long-term effects of inhalation exposure to fiberglass. At a minimum, fiberglass exposed to the air stream in an HVAC system will shed particles and serve as a matrix for collecting dust and dirt that act as a substrate for microbial growth.

Contamination of domestic hot water systems, cooling towers, and condensate pans: continues to result in infections of building occupants on a regular basis. The results of such infections can range from mild to fatal and affect one or many employees. They invariably result in employee apprehension and media attention. Mechanical engineers must be vigilant to avoid system designs that may promote the growth of legionella sp.

Relevant Codes and Standards

Ensure Electrical Safety

Eliminate Exposure to Hazardous Materials

Provide Good Indoor Air Quality (IAQ) and Adequate Ventilation

Provide Ergonomic Work Places to Prevent Work-Related Musculoskeletal Disorders (WMSD)

Perform Proper Building Operations and Maintenance

Additional Resources

WBDG

Design Objectives

Accessible, Functional / Operational, Productive-Promote Health and Well-Being, Productive-Provide Comfortable Environments, Sustainable-Enhance Indoor Environmental Quality (IEQ)

Project Management
Building Commissioning
Publications

Federal Agencies and Programs

Standards and Code Organizations

Associations and Organizations

Tools

Training

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Occupational Safety and Health Administration

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Modern buildings are generally considered safe and healthy working environments. However, the potential for indoor air quality problems, occupational illnesses and injuries, exposure to hazardous materials, and accidental falls beckons architects, engineers, and facility managers to design and maintain buildings and processes that ensure occupant safety and health.

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Structural systems transfer their loading through a series of elements to the ground. This is accomplished by designing the joining of the elements at their intersections. Each connection is designed so that it can transfer, or support, a specific type of load or loading condition.

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The representation of a pinned support includes both horizontal and vertical forces. PINNED CONNECTIONS. In contrast to roller supports, a designer can often utilizepinned connections in a structural system. (you can also use the same link above for the roller support)

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...Floor loadings range from 450 to 1,500 kilograms per square metre (100 to 300 pounds per square foot), and the full range of foundation types is used for them. Spread footings are used, as are pile foundations, which are of two types, bearing and friction. A bearing pile is a device to transmit the load of the building through a layer of soil too weak to take the load to a stronger layer...

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Floor loadings range from 450 to 1,500 kilograms per square metre (100 to 300 pounds per square foot), and the full range of foundation types is used for them. Spread footings are used, as are pile foundations, which are of two types, bearing and friction.

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In determining the code compliance and structural requirements of one of our building design projects, one of the key steps is to calculate the required loads. The load requirements are normally contained in the applicable building code for the project, if there is one.

The occupancy category is simply a number, Roman Numeral I, II, III, or IV, and it affects the load requirement by adjusting the importance factor for the building in relationship to the risk to human life that would exist in the event of the failure AND the importance of avoiding a failure in an emergency due to the nature of the building's function in the event of an emergency. The higher the occupancy category number, the higher the importance of avoiding failure and keeping the building functioning in the event of an emergency.

Determining the correct Occupancy Category at the beginning of your design project using the same criteria that your design professional will allow the project to be analyzed for the correct loads right off the bat and ensure that the design will be efficient and sound for the nature of the building's use throughout the life of the structure.

For certain projects that do not require a building code to be applied, our practice at Halberg Engineering is to apply the normal building design loads for a commercial structure, but to use the lowest Occupancy Category that fits the intended use of the building. This allows the building to be designed to a current standard but also to allow the design loads to be reduced in accordance with the risk to life and property as appropriate for each project.

From Chapter 16 of the International Building Code, the Occupancy Category explanations are shown below. As always, if you have any questions about this information, be sure to contact your design professional as early in the design process as possible!

OCCUPANCY CATEGORY OF BUILDINGS AND OTHER STRUCTURES (from IBC Table 1604.5)

I - Buildings and other structures that represent a low hazard to human life in the event of failure:
Agricultural facilities. Certain temporary facilities. Minor storage facilities.

II - Buildings and other structures except those listed in Occupancy Categories I, III and IV

III - Buildings and other structures that represent a substantial hazard to human life in the event of failure. A few examples include:
Covered structures whose primary occupancy is public assembly with an occupant load greater than 300. Buildings and other structures with elementary school, secondary school or day care facilities with an occupant load greater than 250. Health care facilities with an occupant load of 50 or more resident patients, but not having surgery or emergency treatment
facilities. Jails and detention facilities.

IV - Buildings and other structures designated as essential facilities. A few examples include:
Hospitals and other health care facilities having surgery or emergency treatment facilities. Fire, rescue and police stations and emergency vehicle garages. Designated earthquake, hurricane or other emergency shelters. Buildings and other structures having critical national defense functions.

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In determining the code compliance and structural requirements of one of our building design projects, one of the key steps is to calculate the required loads. The load requirements are normally contained in the applicable building code for the project, if there is one.

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Nominal strength is defined as the. capacity of a structure or component to resist the effects of loads, as determined by. computations using specified material strengths

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A bending moment is the reaction induced in a structural element when an external force or moment is applied to the element causing the element to bend. The most common or simplest structural element subjected to bending momentsis the beam.

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The moment arm or lever armis the perpendicular distance between the line of action of the force and the center of moments.

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Used by architects to refer to an object or space, as in “this doorway is a nice moment.” By using the language of time to refer to space, architects are able to give the impression that they are higher-dimensional superbeings.

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consists of thick reinforced concrete slab covering the entire area of the bottom of the structure like a floor. The slab is reinforced with bars running at right angles to each other both near bottom and top face of the slab. Sometimes it is necessary to carry the excessive column load by an arrangement of inverted main beams and secondary beams, cast monolithically with the raft slab.

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The load path is simply the direction in which each consecutive load will pass through connected members. The sequence commences at the highest point of the structure working all the way down to the footing system, ultimately transferring the total load of the structure to the foundation.

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the weight of people or goods in a building or vehicle.

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Most lateral loads are live loads whose main component is a horizontalforce acting on the structure. Typical lateral loads would be a wind loadagainst a facade, an earthquake, the earth pressure against a beach front retaining wall or the earth pressure against a basement wall

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A kip is an Imperial unit of force. It equals 1000 pounds-force, used primarily by American architects and engineers to measure engineering loads. Although uncommon, it is occasionally also considered a unit of weight, equal to 1000 pounds, i.e., one half of a short ton. One use is as a unit of deadweight to compute shipping charges.

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Internal forces are forces exchanged by the objects in the system.

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A grade beam or grade beam footing is a component of a building's foundation. It consists of a reinforced concrete beam that transmits the load from a bearing wall into spaced foundations such as pile caps or caissons.

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a large iron or steel beam or compound structure used for building bridges and the framework of large buildings.

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a graphical illustration used to visualize the applied forces, movements, and resulting reactions on a body in a steady state condition (no acceleration of the

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the lowest load-bearing part of a building, typically below ground level.

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strength or energy as an attribute of physical action or movement.

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A municipality refers to a village, town, or city that's usually governed by a mayor and council. From this noun, we get the adjective municipal, which you can use to describe something that relates to a town or its government. Your town's city council may have offices in the municipal building downtown.

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Masonry is the building of structures from individual units, which are often laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, building stone such as marble, granite, travertine, and limestone, cast stone, concrete block, glass block, and cob. Masonry is generally a highly durable form of construction. However, the materials used, the quality of the mortar and workmanship, and the pattern in which the units are assembled can significantly affect the durability of the overall masonry construction. A person who constructs masonry is called a mason or bricklayer.

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A secure place for the feet; a foothold. The act of moving on foot. Architecture The supporting base or groundwork of a structure, as for a monument or wall. Also called footer. A basis or foundation: a business begun on a good footing.

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Residential low slope roofing can generally be divided up into two broad categories: larger flat roofed applications (low slope) such as residential condominium complexes, row homes, and town houses and smaller applications such as residential porch and garage transitions from the main home where the slope of the roof changes dramatically from steep slope to low slope on the same structure.

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Fixed supports can resist vertical and horizontal forces as well as a moment. Since they restrain both rotation and translation, they are also known as rigid supports.

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a state in which opposing forces or influences are balanced.

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A load-bearing wall or bearing wall is a wall that bears the weight of the house above said wall, resting upon it by conducting its weight to a foundation structure. The materials most often used to construct load-bearing walls in large buildings are concrete, block, or brick.

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Curtain Wall Architecture Wikipedia The Free Encyclopedia A Building Project In Wuhan China With Relationship Between Inner Load Bearing Structure And Exterior Glass Visible ~ Clipgoo

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Asla professional awards san francisco residence download hi res image. Trend decoration home glass walls for frugal modern and ps. Nrk images blog e architectural perspectives offsetting that however is the glass wall at western.

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A constant load in a structure (as a bridge, building, or machine) that is due to the weight of the members, the supported structure, and permanent attachments or accessories.

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Light gauge steel construction is very similar to wood framed construction in principle - the wooden framing members are replaced with thin steel sections. The steel sections used here are called cold formed sections, meaning that the sections are formed, or given shape at room temperature.

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In a general sense, the design load is the maximum amount of something a system is designed to handle or the maximum amount of something that the system can produce, which are very different meanings. For example, a crane with a design load of 20 tons is designed to be able to lift loads that weigh 20 tons or less.

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the result of an applied force or load. This may be the result of static, constant load application and/or from dynamic, variable loading.

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the degree to which a structural element is displaced under a load. It may refer to an angle or a distance.

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Hybrid architecture s is the result of the hybridization of three diverse natures in one intervention: object-related nature, landscape-related nature and infrastructure-related nature. Consequently, all architectural intervention is defined as hybrid that is at once object, landscape and infrastructure, an architectural intervention that simultaneously meets three conditions:

– It is a physical intervention that, as a result of a project, proposes an architectural space generated on the basis of human intervention.

– It is an architectural intervention, which is at the same time a landscape, beyond simply being an object placed within the landscape: using a variety of possible mechanisms (fusion, transformation, reconfiguration …), the architectural intervention integrates inseparably into the landscape.

– It is at once an architectural intervention and an infrastructure, beyond its connection to infrastructure: in transforming into a section of infrastructure itself, the architectural object becomes a part of the infrastructure and incorporates its laws and mechanisms of functioning.

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A deep foundation is a type of foundation which transfers building loads to the earth farther down from the surface than a shallowfoundation does, to a subsurface layer or a range of depths. A pile is a vertical structural element of a deep foundation, driven or drilleddeep into the ground at the building site.

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The arrangement of windows and doors on the elevations of a building.

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the intrinsic weight of a structure or vehicle, excluding the weight of passengers or goods

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•Exit discharge is that portion of a means of egress between the termination of an exit and a public way

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A continuous beam is a statically indeterminate multispan beam on hinged support. The end spans may be cantilever, may be freely supported or fixed supported. At least one of the supports of a continuous beam must be able to develop a reaction along the beam axis.

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A means of egress is the path available for a person to leave a building, structure, or space.

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an upright pillar, typically cylindrical and made of stone or concrete, supporting an entablature, arch, or other structure or standing alone as a monument.

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An emergency exit in a structure is a special exit for emergencies such as a fire: the combined use of regular and special exits allows for faster evacuation, while it also provides an alternative if the route to the regular exit is blocked by fire, etc.

It is usually a strategically located (e.g. in a stairwell, hallway, or other likely place) outward opening door with a crash bar on it and with exit signs leading to it. The name is a reference to when they are frequently used, however a fire exit can also be a main doorway in or out. A fire escape is a special kind of emergency exit, mounted to the outside of a building.

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a large watertight chamber, open at the bottom from which the water is kept out by air pressure and in which construction work may be carried out under water.

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epdm Acronym in the Miscellaneous - Community, Governmental & Military, Scientific & Educational category and in the Architectural, Architecture, Construction, NASA, Chemistry, Plastics, Polymer terminology.

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external load acting on individual beams. After determining load acting on individual beam, beams can be separated out from beam column system for further analysis.

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A raised floor (also raised flooring, access floor(ing), or raised access computer floor) provides an elevated structural floor above a solid substrate (often a concrete slab) to create a hidden void for the passage of mechanical and electrical services. Raised floors are widely used in modern office buildings, and in specialized areas such as command centers, IT data centers and computer rooms, where there is a requirement to route mechanical services and cables, wiring, and electrical supply. Such flooring can be installed at varying heights from 2 inches (51 mm) to heights above 4 feet (1,200 mm) to suit services that may be accommodated beneath. Additional structural support and lighting are often provided when a floor is raised enough for a person to crawl or even walk beneath.

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a long, sturdy piece of squared timber or metal spanning an opening or part of a building, usually to support the roof or floor above.

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1.

material, as paper or fiberboard, treated in various ways as awaterproof covering for a deck or roof.

2.

material of concrete, asbestos, steel, or the like, in the form of self-supporting flooring or roofing units laid between joists or rafters.

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A curtain wall system is an outer covering of a building in which the outer walls are non-structural, but merely keep the weather out and the occupants in. As the curtain wall is non-structural it can be made of a lightweight material, reducing construction costs. When glass is used as the curtain wall, a great advantage is that natural light can penetrate deeper within the building. The curtain wall façade does not carry any dead load weight from the building other than its own dead load weight. The wall transfers horizontal wind loads that are incident upon it to the main building structure through connections at floors or columns of the building. A curtain wall is designed to resist air and water infiltration, sway induced by wind and seismic forces acting on the building, and its own dead load weight forces.

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A concrete masonry unit (CMU) is a standard size rectangular block used in building construction.

Those that use cinders are called cinder blocks in Canada, the U. S., and New Zealand, breeze blocks in the United Kindom and New Zealand, and hollow blocks in the Philippines. In Australia they are also known as Besser blocks or besser bricks, because the American-based Besser Company was a major supplier of concrete-block-making machinery. Clinker blocks use clinker as aggregate. In non-technical usage, the terms cinder block and breeze block are often generalized to cover all of these varieties.

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A system of internal forces whose resultant is a force acting along the longitudinal axis of a structural member or assembly

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An upright pillar, typically cylindrical and made of stone or concrete, supporting an entablature, arch, or other structure or standing alone as a monument.

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The concrete that is deposited in the place where it will harden as an integral part of the structure, as opposed toprecast concrete.

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Built up roof membranes, referred to by the acronym BUR, have been in use in the U.S. for more than 100 years. These roof systems are commonly referred to as "tar and gravel" roofs. BUR systems generally are composed of alternating layers of bitumen and reinforcing fabrics that create a finished membrane. The number of plies in a cross section is the number of plies on a roof: The term "four plies" denotes a four ply roof membrane construction. Sometimes, a base sheet, used as the bottommost ply, is mechanically fastened. Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation.

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Architecture and Spatial Design

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The allowable stress or allowable strength is the maximum stress (tensile, compressive or bending) that is allowed to be applied on a structural material.