A small stepladder has vertical rails and horizontal steps formed from a C-section aluminum channel (Figure P5.28). Two rivets, one in front and one in back, secure the ends of each step. The rivets attach the steps to the left- and right-hand rails. A 200-lb person stands in the center of a step. If the rivets are formed of 6061-T6 aluminum, what should be the diameter d of the rivets? Use a factor of safety of 6, and round your answer to the nearest 1/16 of an in.

Figure P5.28

B Step A A >B Rail Step Section A-A Rivet Rear rivet Front rivet Section B-B