the unit weight of normal weight reinforced concrete is commonly assumed to be 150 lb/ft cubed. find the weight per lineal foot (lb/ft) for a normal weight reinforced concrete beam that: a. has a rectangular cross section 16 in. wide and 28 in. deep b. has a cross section 38 in. wide at top, 6 in. deep at side,12 in. wide at bottom and 26 in from top to bottom