Negative bending behavior of web-embedded U-shaped steel-concrete composite beams

This paper discusses the negative bending behavior of a new type of web-embedded U-shaped steel-concrete composite beams (WUSCBs). Considering the installation of web-embedded shear connectors, a negative bending moment test was performed on seven WUSCB specimens. The web-embedded shear connectors in the WUSCB are shown to have good shear connection performance and maintain the overall function of WUSCBs. The failure progression of the specimens is characterized by the cracking, yielding, and buckling loads of 0.22Pu, 0.79Pu, and 0.92Pu, respectively. Negative bending failure was observed in the WUSCBs, evidenced by the steel plate yielding and concrete slab cracking. The WUSCBs were found to have good ductility and deformability under negative bending. A finite element model was established to validate the experimental results. The calculation methods for negative bending capacity and effective flange width are proposed; and the calculated results are in good agreement with the test results. A suggested value of moment modulation at the end of continuous beam is proposed.