Steel-High Strength Concrete Beams Nonlinear Analysis

High-performanced steel fiber reinforced concrete (HPFRC)composite girder is widely used in urban road of our coutry. The new type structure in which the steel and steel fiber concrete are integrated by connectors to take advantage of the respective properties of tention and compression. With the continuous application of steel-concrete composite girder which the concrete of the negative moment bending drawn crack, reduce the stiffness of negative moment bending section. It's more and more outstanding to influence the function of this structure. Though mechanical properties of composite girder in the negative moment has a certain amount of researche at the present, it still exists many technical problems in the design theory and practical application.Based on Nonlinear analysis theory and the material properties, nonlinear finite element model of steel-concrete composite beam and prestressed steel-concrete composite beam is done in this paper, as for steel beam and concrete slab, volume units Solid45 and Solid65 are used; the prestress are defined through applying the beginning temperature; slip between concrete slab and the steel beam are considered by adopting the spring unit Combine 39. In the loading process,all composite beams pass through elastic phase,elastic-plastic phase and destruction phase.All specimens fail in bending and display good integrality.Analysized by nonlinear finite element method,bearing capacity,displacement,slipping between concrete slab and the stlle beam are received through calculation of the two types of composite beams in this paper. This paper also provides composite beam's influence caused by different factors,such as concrete's,prestressed steel bar's numbers and presstress,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 flanger rather than the hardening effect of steel grider 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 teinforcement and shear span ratio were discussed.The results based on the ANSYS program consist well with the results from the expeiments.The formula for calculating the ultimate shear capacity is available by comparing the predicted values with the nonlinear analysis results.