The following problems involve material covered in Chapter 13 . The stair tread of the...

The following problems involve material covered in Chapter 13 .

The stair tread of the escalator is supported on two of its sides by the moving pin at A and the roller at B . If a man having a weight of 300 lb stands in the center of the tread, determine the principal stresses developed in the supporting truck on the cross section at point C . The stairs move at constant velocity.