The effects of the shear deformability of composite beams on their long-term and ultimate behaviour

This paper presents a comparative study between the performance of three different beam models to describe the long-term and ultimate behaviour of composite members with partial interaction. In particular, these models are derived coupling by means of a flexible shear connection two Euler-Bernoulli beams (commonly referred to as Newmark beam model), a Euler-Bernoulli beam and a Timoshenko beam, and two Timoshenko beams, respectively. The numerical solutions are obtained by means of the finite element method. The effects of including the shear deformability of the steel joist is discussed at service conditions based on an extensive parametric study carried out on approximately 100 realistic three-span composite beams. The differences in using the three beam models in predicting the ultimate composite behaviour is then discussed using experimental results available in the literature as benchmark problems