The Experiment And Analysis Of The Effective Width Value In Steel-Concrete Composite Beams

The composite structure is a new-type structure and widely used in the world, which inherits the merits of steel structure and reinforced concrete structure. As one of the basic members in the composite structure, the composite beams have been widely researched at home and abroad. The design theory and the code specifications have come into being maturely. But the value of the effective width differs much in the countries. The bearing capacity and rigidity of the composite beams is related to the section dimensions, the allowable value of the ratio of deflection and span, the ratio of span and height, the shear slip of the steel beam and the concrete slab, etc. The adoptive value of the effective width is very pivotal, which is not only related to the real working state but also straightly influential with the section dimensions of the composite beams. It affects the bearing capacity and rigidity of the composite beams. The effective width adopted by the countries commonly is based on that the composite beams are in elastic condition. It is unfit for the method of redistribution analysis of plastic internal force in floor system. Now, the value of the effective width is various in the countries' codes, the code in China is short of deep research and adopts the computational method of T-shape beams in RC structure. The design slab width in available testing members of composite beams is less than the calculating width according to the code in China. So, the author designs four wide-slab and full-size composite beams to research the relation of the effective width and the slab thickness, getting the reasonable value of effective width. The paper combined the advanced achievements of the research of composite beams at home and abroad, discussed how the bearing capacity and deflection change when the effective width varies, and compare the computed results with the experimental results. It is found that in elastic phase the effective width is similar on the whole and accords with the experimental results well. But when in plastic phase the effective width adopted by the codes is inclined to less than the actual effective width greatly. In the end, the author adopted the finite-element analysis software to research the bearing capacity, deflection and the stress distribution of concrete slab. It is found that the analysis result inosculates the experimental result well. The suggested value in this paper can be applied to the analysis and design of steel-concrete composite beams.