Two C100 x 10.8 channels are joined to 120-mm by 7.5-mm plates with 10-mm rivets to form the beam shown in the figure. The beam carries a uniformly distributed loading of intensity wo over its 4-m simply supported span. (a) If the working bending stress is 120 MPa, find the largest allowable value of wo. (b) Determine the largest allowable spacing of rivets using 80 MPa as the working stress for rivets in shear. 7.5 mm C100 x 10.8 FIG. P5.124 120 mm