Modelling of shear bond behaviour of composite sections with axial loads

Abstract

In this study, the shear bond behavior of steel and concrete composite beams under axial effects has been investigated using the finite element technique. A comprehensive review of various existing theories and finite element models in analyzing shear connection in this type of beams in general, has been conducted and a summary is presented in this thesis. An effort has been made to achieve a proper shear connection under axial effects, by using a standard linear frame type finite element. In addition, the conventional method of using linear spring elements to model the shear connection in steel and concrete structural elements has also been considered. SAP90 finite element software has been used for developing all the finite element models presented in this thesis. The finite element models developed have been verified against experimental work conducted by others on a composite stub girder floor system where concrete slab is subjected to bending, shear and axial forces at certain locations. From the work carried out by this study, it had been concluded that the linear frame type finite element has its limitations in modeling the shear connection under axial effects. However, acceptable shear force values could be predicted in the shear connectors by using this type of finite elements. It has also been found that the conventional linear spring elements developed to model the shear connection, may not be valid in the presence of axial effects. However, it may still be possible to use linear spring elements with some modifications to its stiffness. A modification has been proposed in the current thesis to the stiffness of the spring element which had been developed by Ohelers et al. [15].