Truss stress compressive/tensile stress

In summary, when determining the metal for each truss member, you must calculate the compressive truss member as a column and find the critical buckling load using the equation Pcr = (pi/L)^2 E I, where Pcr is the critical buckling force, L is the length of the column, E is the modulus of elasticity, and I is the minimum area moment of inertia for the cross-sectional shape.
  • #1
peet_dk
10
0
Hi

I have found out which truss member that have compressive stress, and which have tensile.
Now I have to select the metal for each member, I know how to find it when it is simple tensile stress (Sigma=Force/Area) But I think there is another equation when it is compressive stress, or?

Do I have to calculate the compressive truss member as a column, and find the critical buckling load?
 
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  • #2
Yes. The buckling equation for long slender members is Pcr = (pi/L)^2 E I, where Pcr is the critical buckling force, L is the length of the column, E is the modulus of elasticity of the material you're using, and I is the minimum area moment of inertia (second moment of area) for the cross-sectional shape you're using.

-David
 

1. What is truss stress?

Truss stress refers to the internal forces or stresses that act on the structural components of a truss, which is a type of engineering structure commonly used in bridges, roofs, and other large buildings.

2. What is the difference between compressive and tensile stress in a truss?

Compressive stress occurs when a force is applied to a truss that pushes the structural members closer together, causing them to compress. Tensile stress, on the other hand, occurs when a force pulls the structural members apart, causing them to elongate.

3. How is truss stress calculated?

Truss stress is typically calculated using the equations of statics and the principles of mechanics, taking into account the forces acting on the truss and the properties of the structural members such as their cross-sectional area and material strength.

4. What are the factors that affect truss stress?

The factors that can affect truss stress include the design and geometry of the truss, the magnitude and direction of the applied loads, the properties and strength of the truss materials, and any external constraints on the truss such as supports or connections to other structures.

5. How can truss stress be minimized?

To minimize truss stress, engineers can optimize the design and geometry of the truss, carefully consider the loadings and supports on the structure, and choose appropriate materials with sufficient strength and stiffness to handle the expected loads.

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