Moment redistribution in steel-concrete continuous composite beams

The research focuses on the flexural behaviour of continuous composite beams, laterally restrained, at Ultimate Limit State (ULS). Numerical finite element models are developed with ADAPTIC [1] in order to calculate the ultimate rotation capacity of the beams, which is limited by the local buckling of structural steel and/or the maximum elongation of reinforcing bars. Nonlinear behaviour of the component materials is taken into account. The objective is to use the numerical results to calculate the permissible moment redistribution that satisfies the ULS requirements. A parametric study is carried out. The influence of the loading and the degree of shear connection is investigated too. The results obtained are discussed and compared with the moment redistribution limits provided by current codes of practice. At the expenses of the results obtained, it seems that the limits stated by these codes are unconservative for some types of beams, under specific circumstances.