Question

Truss Analysis

1.      Select a material and a cross section for the members.

2.      Choose four arbitrarily placed points. Connect them as two triangles. No members can be vertical or horizontal and none can be aligned.

3.      Draw the truss and label the measured lengths.

4.      Select two support points and two load points.

5.      Load the truss vertically with a load at each load point.

6.      Calculate the reactions and the forces within the members.

7.      Calculate the change of lengths of the members and label the new positions.

8.      Determine the axial member stresses and strains.

9.      Determine the maximum shear stress using Mohr’s circle for two of the members.

10.    Determine the critical buckling load and critical buckling stresses for members in compression.

11.    If one of the members had a load perpendicular to it axis at the midpoint of the length what would be its deflection?

12.       Using the deflection as the eccentricity what would be the additional flexural stress due to this eccentricity?

Answer 1

1. Let us select steel material for the truss. The youngs modulus of steel, E = 2x10⁵ N/mm²; let the truss be of 50 mm dia, so the cross sectional area will be A = (pi/4)50² = 1962.5mm²

2. Let us choose the points (0,0); (1,0.25); (1.25,1.25) and (0.25,1). The below diagram shows the points with the truss. No members will be horizontal and vertical. All the members are alligned.