Experimental Study On Shear Behavior Of Steel-Concrete Composite Beams Under Negative Moment

Steel and concrete composite structure is a new type of structure and has been widely used in engineering in recent years. Based on summarizing the present situation of the steel-concrete composite beam, three models of composite beams under negative moment were designed and tested.According to the experiment of steel-concrete composite beams, the loading and failure process of the composite beams were deserved. The vertical shear-deflection curve of mid-span, the slip curve of interface between the shape steel and concrete and strain curve of mid-span along the profile height were defined. Bearing capacity and ductility of composite beams were conducted with consideration of the shear connection degree and the arrangement of shear connector.In terms of the experimental study and former researches, shear failure features and mechanism of composite beams under negative moment were described. The plastic analysis of steel show that the increase in shear strength for steel-concrete composite beams under negative moment is due to the contribution of concrete flange rather than the hardening effect of steel girder webs. The related formula for calculating the shear strength of the composite beam under negative moment was proposed. The predicted values are in good agreement with the experimental results.Nonlinear simulations with ANSYS program were carried out to analyze the shear resistance of steel-concrete composite beams. The effect of the ratio of longitudinal reinforcement and shear span ratio were discussed. The results based on the ANSYS program consist well with the results from the experiments. The formula for calculating the ultimate shear capacity is available by comparing the predicted values with the nonlinear analysis results.This paper is helpful for the further studies on the shear behavior of steel-concrete composite beams under negative moment and the engineering design.