Design of Bent Caps for Concrete Box-Girder Bridges

Design recommendations for integral bent caps in straight, continuous, reinforced concrete box-girder bridges were developed from the results of a combined experimental and analytical investigation. The results of the investigation indicate that reductions in the amount of flexural reinforcement in the bent cap of up to 40 percent can be made without reducing safety and while maintaining adequate serviceability. Even greater reductions in the amount of reinforcement can be made for bent caps with flared columns. Most of this improved economy results from a change from the working stress method of design to the load factor method of design. Test variables included the distribution of loads on the bent cap, the effect of flaring the column in the plane of the bent, the effective flange width of the bent cap in tension and in compression, the effect of spreading the main tensile reinforcement into the adjacent superstructure, and the location of the critical design sections.