Question: A plate girder used as a simple beam 36 ft long must support a concentrated load of 180 000 lb at the middle of the span and 45 000 lb at each quarter point. The girder is composed of a 48- by I-in web plate and four 6- by 6- by flange angles, all made of A36 structural steel. What should be the bolt spacing if Trill A307 bolts are used? Use the AISC code. Assume bearing-type connections.