Q13 For the beam section shown in Figure Q13, the structure has been idealised into booms (B1-B5) which carry all the direct stresses and thin web sections between which only resist shear forces. The section is symmetrical about the y axis. 6a B4 B3 ******************** S a Your tasks are: a) To find the maximum shear stress in the section b) To find the rate of twist of the section B5 ************** B2 4a ********** B1 Figure Q13 The areas of the booms are as follows: B1 = 2500 mm B2 = B5 = 4000 mm B3 = B4 = 1cd0 mm where c and d are the last two digits of your student number. As an example, if your student number is 965337, then the areas of B3 and B4 would be 1370 mm. The thickness of all the webs is constant at 2.0 mm; the value of a is 80 mm and the shear modulus is constant at G = 40,000 N/mm A shear force S = 160 kN is applied a distance a to the left of B5 as shown above.