Dimensionless formulation and comparative study of analytical models for composite beams in partial interaction

Steel–concrete composite beams are widely utilized as cost-effective structural solution in both buildings and bridges. Partial interaction through the possible occurrence of slips at the interface between the two connected members, strongly affects the behaviour of composite members and, therefore must be incorporated in theoretical models dealing with composite members. In addition, shear deformability of the two connected layers cannot be ignored in stocky members. Several computational models simulating the behaviour of composite beams including partial interaction and shear deformability with various degree of sophistication are currently available in the scientific literature. The present paper focuses on the background and the mechanical assumptions adopted in these models as well as structural characteristics which actually govern their predictions. Based on the kinematic assumptions involved, a threefold classification is proposed. The paper further clarifies the hierarchy between the three groups of models. To do so, the governing equations for each group of models are transformed into a proper dimensionless form by using mechanically sound dimensionless expressions of all functions of interest involved in the description of the mechanical response of the composite beam. A thorough parametrical study is presented which quantifies the influence of the identified dimensionless parameters. Furthermore, the study clearly indicates possible threshold values beyond which certain effects become negligible.