ENGINEERING MECHANICS ASSIGNMENT-

QUESTION 1-

a) For the truss shown above the counters are flexible rods which carry tension only.

i). Use the method of sections through IJ, IN, ND and DC to calculate the force in member IJ.

ii). Knowing IJ, take another section through the truss to determine whether FI or DG is the counter that is acting in tension. Explain why you think this counter is the one acting in tension.

iii). Determine the magnitude of the tension force acting in the counter you selected in part (ii).

b) In the diagram of the truss shown above the reaction at the roller at I is 4.25 kN upwards. Using the method of joints, calculate the force in member FH.

c) Assuming you know what the reactions are at A and I, if you start at joint A, can you solve for the force in all members of the truss by only using the method of joints? Why, or why not?

QUESTION 2-

a) The truss shown above carries the two loads at B and C as indicated.

i). Use the method of joints starting at joint C to determine the force in every member of the truss. Indicate these forces on a line diagram of the truss.

ii). Determine the reactions at the pin supports at A and D.

iii). A further 1 kN load is applied on EC as indicated by the broken line in the diagram. Discuss, without any calculations, why this would normally be considered bad practice for this type of structure and what the probable result would be.

b) For the three pin arch shown below determine the reactions at A and C.

QUESTION 3-

Each member of the truss shown above can safely support a tensile force of 50 kN and a compressive force of 40 kN. Based on these limits, what is the largest downward load F that can safely be applied at C?

QUESTION 4-

a) Using one section only, use the method of sections to calculate the force in truss member FI in the truss shown to the left.

b) Using the method of sections and/or the method of joints calculate the force in members EG and GJ in this truss.

c) For the pin-jointed frame shown above, calculate the force in member BE.

d) Why is this structure referred to as a frame and not a truss?

QUESTION 5-

a) For the truss shown above:

a. Identify the zero force members and indicate these on the diagram above. Justify your selection.

b. Determine the force in all members of the truss using any combination of methods that you choose.