Solving Truss Equations: Find Force in Members EA, EF and EG

Click For Summary
SUMMARY

This discussion focuses on solving truss equations to find the forces in members EA, EF, and EG, given specific loads and support conditions. The user identified the vertical reaction forces at supports A and G as 13 kg-f and 17 kg-f, respectively, and established a horizontal equilibrium equation. The method of sections was employed to analyze the truss, leading to a moment equation involving member AE. The user seeks efficient methods and tools for solving such statically indeterminate truss problems, expressing frustration with manual calculations and data input into an Android app.

PREREQUISITES
  • Understanding of static equilibrium principles in truss analysis
  • Familiarity with the method of sections and method of joints
  • Knowledge of moment calculations in structural analysis
  • Experience with statically indeterminate structures
NEXT STEPS
  • Research software tools for structural analysis, such as SAP2000 or RISA
  • Learn advanced techniques for analyzing statically indeterminate trusses
  • Explore the use of finite element analysis (FEA) for complex truss problems
  • Study the principles of deformation and boundary conditions in structural mechanics
USEFUL FOR

This discussion is beneficial for civil engineers, structural analysts, and students studying mechanics of materials who are looking to enhance their understanding of truss analysis and computational tools for solving structural problems.

arestes
Messages
84
Reaction score
4

Homework Statement


Find force in members EA, EF and EG given the loads shown. A and G are pinned supports.

Homework Equations


Three equations of equilibrium for sections (method of sections) 2 equations for any node (method of joints).
I also used the dimensions to decompose member forces.

The Attempt at a Solution


I started by analyzing the entire truss to get something about the reactions. I found both VERTICAL components of A and G to be 13 kg-f and 17 kg-f respectively, the horizontal components fulfill : $$A_x + G_x =15 $$

Then I made a cut through BF, CF and AE and evaluated moments about F to get:
$$ \frac{32}{\sqrt{17}}AE=128-4A_x$$

All my other attempts involve the other unknowns and I can't still get them together. What would be the quickest way without throwing in a bunch of equations till I finally reach the answer?
*** I need to teach this and I can't see the "trick" if there is one, so I can teach whatever that trick is supposed to tell me.
BTW,I put this onto an android app and got the solutions. It was painful to input all the data. Do you recommend a particular app or program for these problems?
 

Attachments

  • truss 1.jpg
    truss 1.jpg
    48.2 KB · Views: 515
Physics news on Phys.org
Truss is externally statically indeterminate because you have 4 unknown reaction forces and just three equilibrium equations, and to solve it by hand calcs is as bit tedious because it requires deformation and boundary conditions analysis. I wonder who makes up these problems?
 
  • Like
Likes   Reactions: arestes

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K