How to calculate tension/compression in a truss bridge (diagram shown)?

  • Thread starter Thread starter enosthapa
  • Start date Start date
  • Tags Tags
    Bridge Truss
Click For Summary
SUMMARY

This discussion focuses on calculating tension and compression forces in a truss bridge, specifically when a load is applied at the midpoint between two joints. Participants suggest splitting the central load into two equal forces and emphasize using the method of joints rather than the method of sections for analysis. The method of joints allows for treating the external load as a moment on the joint being analyzed, ensuring force equilibrium. The conversation highlights the importance of starting calculations from the supports and progressing towards the center of the truss.

PREREQUISITES
  • Understanding of truss bridge design principles
  • Familiarity with the method of joints in structural analysis
  • Basic knowledge of force equilibrium concepts
  • Ability to interpret truss diagrams and load distributions
NEXT STEPS
  • Study the method of joints in detail for truss analysis
  • Learn about calculating moments in structural engineering
  • Explore software tools for structural analysis, such as SAP2000 or ANSYS
  • Research common mistakes in truss calculations and how to avoid them
USEFUL FOR

Civil engineers, structural analysts, and students studying truss bridge design and analysis will benefit from this discussion.

enosthapa
Messages
9
Reaction score
0
In general, in a truss diagram the forces like load, reaction force are act on joints but in this case the load is in the middle of two joints. How can I find forces on members in this case?

9qfdw6.jpg


Your help is really appreciated. Thank you for reading
 
Engineering news on Phys.org
Since the force is in the center of the spar, you could split it into 2 5N forces at its ends...
 
Mech_Engineer said:
Since the force is in the center of the spar, you could split it into 2 5N forces at its ends...

Could you help me find out what force (tension/compression) do the truss members have please? I have done most of them but the middle section with "X" trusses are making it dificult to calculate the forces the carry...
 
346oy09.jpg

I have done some calculations to find out the forces but i am confused with the middle section. Can someone tell me if figure 2 is correct or not?Thank you
 
Last edited:
You can just assume one or the other (tension or compresison) and if you guessed wrong, you will get a negative value.
 
enosthapa said:
In general, in a truss diagram the forces like load, reaction force are act on joints but in this case the load is in the middle of two joints. How can I find forces on members in this case?

9qfdw6.jpg


Your help is really appreciated. Thank you for reading

Well, you can't use method of sections for the center... you'd have to use method of joints and treat that "external load" as a moment on the joint you're analyzing that's "connected" to the member that's loaded (as well as in force equilibrium)... seems as if the only two joints you'd concern yourself with with that center load are the ones to the left and right of it. at least that's how id attempt to do it. start at the supports and move your way towards the center.
 

Similar threads

Understanding Truss Analysis: Investigating the Accuracy of a Bridge Design App
  • · Replies 3 ·
Replies
3
Views
3K
How to check the Stability of ANY Truss?
  • · Replies 1 ·
Replies
1
Views
2K
Solving trusses with the Direct Stiffness Method
  • · Replies 1 ·
Replies
1
Views
3K
What causes the change in direction of CD in a truss free body diagram?
  • · Replies 2 ·
Replies
2
Views
4K
Forces in a Howe truss (2D) pinned at BOTH ends
  • · Replies 18 ·
Replies
18
Views
6K
Method of Joints Query: Shedding Light On Truss Calculations
  • · Replies 1 ·
Replies
1
Views
2K
What do the numbers in the method of joints analysis for trusses represent?
  • · Replies 3 ·
Replies
3
Views
4K
Statics: Statically Indeterminate Unstable Plane Truss
  • · Replies 4 ·
Replies
4
Views
5K
Force distribution on a K-Truss
  • · Replies 4 ·
Replies
4
Views
19K
Undergrad Tension/compression in curved truss? (Diagram attached)
  • · Replies 2 ·
Replies
2
Views
1K