Truss Concept Map Activity by VERONICA MORSE https://padlet.com/vmorse4/p9253vkjv60fyijb en-us 2021-03-11 20:51:28 UTC 2021-03-11 22:14:19 UTC hello@padlet.com Rigid-body equilibrium vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300260233 Rigid-Body Equilibrium has a moment, unlike Particle equilibrium. 3 equations. Forces in the x and y-direction along with a moment in the z-direction.
Moment = Force x Distance (shortest distance from a point to force's line of action)
]]> 2021-03-11 21:04:34 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300260233 Reactions at support vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300260828 Think about which way it can and can't move, if it can't move in a certain direction there is a reaction force there.
We calculate the reactions by utilizing equilibrium equations along each axis.
]]> 2021-03-11 21:04:45 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300260828 Method of joints vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300261666 This method is related to the prior concepts of static equilibrium and free body diagrams. Start with the joint connected to 3 forces.]]> 2021-03-11 21:05:01 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300261666 Method of sections vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300262427 This method is related to the prior concepts of static equilibrium, free body diagrams, and moments. Steps: make a cut, draw FBD of one of the sections, solve the 2D equilibrium problem.]]> 2021-03-11 21:05:16 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300262427 Making a cut vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300263000 Choose a section that gives 3 unknowns since we only have 3 equations.]]> 2021-03-11 21:05:27 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300263000 Which method to pick? vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300263558 Method of joints: when all member forces are desired.
Method of sections: when only a few member forces are desired.
Combination: when truss contains lots of joints, start with method of sections.]]> 2021-03-11 21:05:37 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300263558 Determinate trusses vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300264127 A truss is determinate if the number of unknowns equals the number of equations present. The number of equations can be found by determining the number of joints present and multiplying that number by 2. The number of unknowns is found by adding the number of members plus the number of reactions. If equations outnumber the unknowns, it is partial fixity. If the number of unknowns equals the number of equations, the truss is statically determinate if full fixity. If unknowns outnumber equations present, it is statically indeterminate.]]> 2021-03-11 21:05:48 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300264127 Making sense of the results vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300264800 In the FBD tension is drawn as an arrow pointing away from the center, whereas compression is an arrow pointing towards the center. It is drawn this way so you know at the end if the force is tension or compression based on the sign. If you get a negative answer it means you drew the force in the wrong direction in the FBD.]]> 2021-03-11 21:06:00 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300264800 Zero-force members vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300265236 Members with F = 0. When there are 3 members and only two are aligned, the nonaligned member carries no force. When there are 2 members and they are not aligned, they each carry no force.]]> 2021-03-11 21:06:08 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300265236 Central question vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300266394 How to analyze a 2-D truss structure?]]> 2021-03-11 21:06:30 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300266394 Particle equilibrium vmorse4 https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300267010 Solve using a system of 2 equations and the known sum of the forces being equal to 0. Forces in the x-direction and forces in the y-direction.]]> 2021-03-11 21:06:41 UTC https://padlet.com/vmorse4/p9253vkjv60fyijb/wish/1300267010