Bridge truss Static Equilibrium

AI Thread Summary
The discussion revolves around calculating the forces of tension or compression in a bridge truss structure, specifically focusing on components T_AC and T_CE. The problem involves a bridge truss spanning 214 meters with a car weighing 1270 kg at the center, and the structure is designed to allow horizontal sliding for thermal expansion. Participants suggest using Lami's Theorem and the method of joints to determine the forces in the truss members. It is clarified that T_AC can be calculated as the horizontal component of the force in member AB, leading to the conclusion that T_AC equals T_AB multiplied by the cosine of 35 degrees. The discussion emphasizes the application of static equilibrium principles in structural analysis.
pegasus24
Messages
14
Reaction score
0

Homework Statement


A bridge truss extends x = 214 m across a river (Fig. P12.68) where θ = 35°. The structure is free to slide horizontally to permit thermal expansion. The structural components are connected by pin joints, and the masses of the bars are small compared with the mass of a 1270 kg car at the center. Calculate the force of tension or compression in each structural component.

Homework Equations


Lami's Theorem
A/sin a = B/sin b = C/sin c

The Attempt at a Solution


I found the forces in most of the members except T_AC and T_CE.
How do i find the force? Should I use moment equation? Is so how should I apply it?
 

Attachments

  • bridge.gif
    bridge.gif
    8.6 KB · Views: 1,578
Physics news on Phys.org
If you have correctly solved for the force in AB, then T_AC is just the horizontal component of the force in AB. Use the method of joints.

Welcome to PF!:smile:
 
PhanthomJay said:
If you have correctly solved for the force in AB, then T_AC is just the horizontal component of the force in AB. Use the method of joints.

Welcome to PF!:smile:

Thanks a lot.. I got it right now.. T_AC = T_AB cos 35
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...

Similar threads

Back
Top