Show clearly each stage of your working for part (b). Include diagrams where appropriate.   a.Joints in real structural frameworks are often...

Show clearly each stage of your working for part (b). Include diagrams where appropriate.

a.Joints in real structural frameworks are often clamped, bolted or welded to prevent the links from moving relative to each other. Explain why this is not strictly necessary and why using a true pin joint may be preferable in many circumstances.

b.Figure 2 shows a 3-member roof truss with a force applied to the top of the truss. Determine the internal forces in each member of the truss and explain whether each member is in tension or compression. Provide appropriate free body diagrams for each step of your calculation.

c.Tensile test was conducted for the material used to make the truss. The tensile test data are shown in Table 1. The length of the tensile test specimen was 50 mm and its cross-section measured 15 × 15 mm2.

Table 1  Force–extension data for Question 2

i.Convert the data in Table 1 to stress and strain. Then plot these new data on a graph, labelling the axes clearly. (You may use graph-drawing software such as a spread-sheet program, or draw the graph by hand).

ii.Using your graph from part c(i) determine (approximately) the following material properties explaining how they are measured:

◦the Young’s modulus

◦its yield stress

◦its 0.2% proof stress

◦its tensile strength.

d.Explain which of the four properties is most important when determining the use of the material in a load-bearing situation. Explain how this information is used to design the members in the truss