Numerical analysis and design of continuous composite beams exhibiting moment redistribution

In this paper, a research and development project is reported which aims to develop numerical analysis and design models for practical design of composite beams in building construction. In a complementary paper, two dimensional finite element studies on simply supported composite beams under sagging and hogging moments are presented while three dimensional non-linear finite element models are described in this paper. Both solid and shell elements are employed to model the concrete flanges and the steel sections while shear connectors are modelled as a series of horizontal and vertical springs along the interfaces between the concrete flanges and the steel sections; non-linear load slippage curves of flexible shear connectors are readily incorporated. After careful calibration against test data, finite element studies of continuous composite beams exhibiting moment redistribution are described. It is demonstrated that the numerical results compare well with test data in terms of various structural characteristics along the entire deformation ranges. In general, it is found that continuous composite beams often fail with a two stage mechanism involving the formation of two plastic hinges at both internal supports and near mid-spans. Moreover, the degree of moment redistribution is readily predicted with the proposed models, and comparison between the test data and the numerical results is found to be highly satisfactory. Hence, the proposed models are considered to be effective for continuous composite beams with practical geometrical dimensions and arrangements. Structural engineers are strongly encouraged to employ the models in their practical work to exploit the full advantages offered by composite construction.© 2006 Taylor & Francis Group,.