Precast Concrete Roof Structure: Failure and Repair

Abstract

Heavy concrete fragments crashing into the floor of a huge warehouse building, from an overhead precast structure, calls for an investigation to determine the cause of this phenomenon and stop it. Field observations show that the roof double‐tees are bearing on the edge of improperly reinforced concrete flanges of precast I‐girders. This causes cracking and eventual fallout of fragments of the girder flange. As a result, bearing of some of the double‐tees is reduced to 1.5 in., an unacceptable amount. Such precarious support could cause sudden and catastrophic failure. The shortcomings of the original design are identified, and a correct design that would have prevented failure is presented herein. The latter would have included use of elastomeric bearing plates and additional reinforcement in the girder flange; actual details are shown. Repair is accomplished locally at the affected double‐tees, using a simple solution made out of structural steel; a full description including details is given.