Influence of shear connectors on the elastic behaviour of composite girders

摘要

The effect of deformable and rigid connectors and influence of connection parameters on the behaviour of composite girders is examined. Both the elastic and plastic behaviour are discussed, but the former one is the main concern. Deformable connectors cause slip in the joint, which results in redistribution of internal forces and changes in the deformed shape of the beam compared to the connection with rigid connectors.The aim of this study is to complement the analytical methods and develop numerical models – based on the author's experimental research – capable to provide reliable parametric studies of three-dimensional structural models of composite girders with deformable and rigid connectors.At first, the partial interaction problem, behaviour of composite girders in the case of various loading types, recent development and real behaviour of connections of composite girders is discussed in the introduction. It is followed by a detailed literature survey serving the purpose of this study. This survey comprises two main parts: analytical and numerical models of composite girders. Among the analytical models, statical and energy methods are considered. The author also developed a new kind of energy method based on variational calculation for determination of shear force distribution of shear connectors of composite girders. The new method is in compliance with the experimental and the latest theoretical investigations. Next, experimental study on steel-concrete and wood-plywood composite girders conducted by the author at the Budapest University of Technology and Economics and Helsinki University of Technology respectively, are presented as well.Experimental studies are followed by parametric studies based on analytical and finite element analyses in order to examine how changes in the connector stiffness affect the behaviour of composite girders. Based on these parametric studies, new design formulas are developed for design practice. The main results obtained by the author are: development of energy method based on the variation calculation, elaboration of a parametric study for determining the elastic shear force for all cross-sections and spans, use of photoelastic method to verify shear stresses near to the beam end, simulation of temperature effect, and development of a FEM model providing results that show good compliance with experimental results.