Comparison and validation of displacement and mixed elements for the non-linear analysis of continuous composite beams

A new three-field mixed beam element and two previously introduced displacement-based beam elements are adopted for the non-linear analysis of composite beams with deformable shear connection. The formulation considers the non-linear behaviour of materials and shear connection. Numerical applications are performed using as working examples steel–concrete two-span continuous beams, a problem of practical interest in structural engineering and a difficult test for composite beam elements. The results are discussed and comparisons are made between the mixed and displacement-based elements. Comparisons with experimental tests are also discussed in order to validate the numerical model and provide indications for reliable non-linear analyses.