Nonlinear Analysis Of Steel-Concrete Composite Beams Considering The Effect Of Interface Slip

Steel-concrete composite beam is developed on the basis of steel structure and concrete structure. It combines the advantages of both the steel material and the concrete material, and makes up for deficiencies of the two materials to a great extent. Since put forward, steel-concrete composite beam has been widely used in engineering practice, and, with the development of society and economy, it has a broader space for development.Firstly, existing calculation methods of steel-concrete composite beam deformation and bearing capacity are reviewed by the author. Most of these methods adopt assumptions ignoring slip effects or regarding shear connector stiffness as a constant, which is inconsistent with actual mechanical behaviors. It is necessary to consider nonlinear load-slip relationship of shear connectors to contribute a profound research on mechanical behaviors of steel-concrete composite beam. Through statistical induction, this paper compares studies on bearing capacity of stud connectors with load-slip curves, thus obtaining a reasonable formula to calculate bearing capacity and load-slip curve.Secondly, the paper introduces OpenSEES finite element program and, based on this program, proposes double-layer fiber beam model for steel-concrete composite calculations. Steel beam and concrete slab adopt two independent fiber beam elements respectively for simulation. At the interface, zero length is set to simulate the load-slip relationship of shear connectors. The node of zero length element is connected with that of steel beam and concrete lab through rigid beam element, which enables their simultaneous bending. C++ programming language is also used for secondary development of OpenSEES, adding a new uniaxial material, namely MyUniaxialMaterial. This material, by self-defining some points on the curve, can replace curve by straight line to simulate nonlinear load-slip relationship of shear connectors.Finally, based on the double-layer fiber beam element model proposed in this paper, a full-range analysis on a set of simply supported steel-concrete composite beams and a set of steel-concrete continuous beams is carried out. The results show that the proposed method can help carry out comparatively accurate simulations on various steel-concrete composite beams.