(Solved): The purlins were designed and installed on the Pratt truss as shown in Figure Q3. However, during ...

The purlins were designed and installed on the Pratt truss as shown in Figure Q3. However, during the construction, the contractor adds more services equipment on the purlins that were not considered during the design stage. Given : Design load on purlins with additional services $=30\mathrm{kN}$ Size of purlin (equal angle) $=120\times 120\times 10\mathrm{L}$ (a) Check whether the size of purlins are satisfactory or not with the new design load. (5 marks) (b) If the purlins are not satisfied, suggest the new size of the purlins. (10 marks) (c) If the purlins cannot be replaced because the construction work had been done, discuss in detail (including sketches if needed) how to make sure the truss system can be used. (10 marks)