China Builds Record Bridge

China’s Hanjiang Railway Bridge has a 1,000 ft (305 m) long main box girder and is the longest bridge of its type in the world. The steel box girder bridge is built with a slant leg on each side, composed of two branches. Cross beams connect the two branches to form a multistory stand, supporting the girder so that the main girder acts like a multi-spanned continuous girder with relatively even bending moment distributed along it. The Hanjiang Bridge was built on the basis of the design studies of earlier steel box girder bridges in China. Engineers for the Hanjiang Bridge solved two stability problems: stability of the web plate of the box girder and the lateral stability of the narrow box section slant-legged rigid frame. The stability of the web plate under bending moment, shear and local compression and the influence of ribs were investigated. The arrangement of the stiffening ribs and the method of stability calculation of web plate used in the design have been proved by the agreement of the experimental results. Both local stability and the overall stability are obtained provided that the position and stability of the stiffening ribs meets the design requirements. The most crucial point in ensuring lateral stability is to find the most effective means to eliminate the lateral displacement at the top of the slant legs. This is accomplished by spreading each leg into two branches with a slope of 1/6 in the transverse direction. The lateral displacement was proved to be within the given limits.