Simplified elastic and elasticplastic analysis of continuous composite beams

Continuous composite beams offer significant benefits over simply-supported composite beams: the load carrying capacity of otherwise identical beams is increased by 15-40% and the deflections are reduced by 60-70%. However, the elastic or elastic-plastic analysis of a continuous composite beam must satisfy compatibility as well as equilibrium. Due to cracking of the concrete slab in negative moment regions, the bending moment distribution and the variation of beam stiffness are interdependent, which in the past has required the use of iterative solution procedures. This paper presents a simple method for the elastic or elastic-plastic analysis of continuous composite beams. By applying the moment area theorems, the point of contraflexure is obtained directly without the need for iteration and can be used either in hand calculations or as the starting point for a more sophisticated analysis. The method is applied to calculating the beam deflections, the level of moment redistribution, and the rotation demand at connections.