Experimental Study of Innovative Steel-Concrete Composite Beams Under Hogging Moment

摘要

This paper presents an innovative solution for steel-concrete composite beams under hogging moment. Compared to normal composite beams, additional concrete was cast inside the steel box girder of these innovative composite beams, aimed to increase the resistance to hogging moment. Bending tests were performed on three series of beams including four innovative composite beams and five normal composite beams. The load-displacement curves, load-crack width curves and ultimate strengths of test specimens were recorded. It was shown that concrete inside the steel box girder effectively enhanced the stiffness and ultimate strength of composite beams under hogging moment. The crack widths of concrete slab were reduced. In addition, the resistance to local buckling of the steel box girder was also remarkably enhanced due to the concrete inside. Design equations for determining the ultimate bending strength of the proposed solution were proposed, with particular emphasis for transverse sections under hogging moments. The results of those equations in terms of ultimate bending capacity complied well with the observed experimental results.