Flexural behaviour of composite beams with high strength steel

Abstract

In framed buildings, the application of high strength (HS) steel in composite beams is not only beneficial in reducing the self-weight of the structure, but the increased-strength attribute of HS steel is also utilised because most of the steel section in composite beams is in tension and buckling is not an issue. Despite this, published research of HS steel–concrete composite beams is quite limited, and it is not yet considered in current national design standards. A three-dimensional finite element model is developed in this paper to investigate the bending behaviour of simply supported HS steel–concrete composite beams. Both geometric and material non-linear behaviour are taken into account. The numerical model is validated by using a number of existing experimental results, and then employed to undertake a parametric analysis. Forty beams with various steel grades and degrees of shear connection are modelled, and the results are compared with those obtained utilising current design standards. The bending strength, stiffness and slip at the interface are investigated, and the effects of the steel grade and degree of shear connection are elucidated. New design approaches are proposed in order to estimate the bending behaviour of simply supported composite beams with HS steel, providing more reliable and economical design solutions for such members.