Analysis On Flexural Behavior Of Steel-Concrete Beams And Bearing Capacity Calculation In The Negative Moment Area

Steel-concrete composite beam is a kind of T-beam composed of steel beams and concrete slabs integrated by connector, which combines the advantages of the steel structures and concrete structures. In China, the steel-concrete composite beams develop rapidly and applicate widely, the design theory and the calculation method has been incorporated into the design of steel structures in China. Engineering practice of steel-concrete composite beam proves its full play to the respective material properties of steel and concrete, and developing the kind of structure is suitable for the context of national infrastructure construction. This means steel-concrete composite beam will play an important role in the futrue structural system, so it is significant to carry out the study on the behavior of the composite beams.A three-dimensional finite element model was established to analyze the nonlinear behavior of continuous I-section steel-concrete composite beams. By comparing with mid-span load-deflection P-δ curves and the ultimate bearing capacity at single span of continuous composite beam from the finite element model and experiment, the good accordance between calculated and the experimental results proved the rationality and validity of the model. Then the mechanism of bending failure, the carrying capacity and the main influencing factors were investigated by using the validated model. The effects of the strength of steel beam, the thickness of web, strength of concrete and ratio of steel reinforcement of slab on the bending behavior of the continuous composite beams were discussed.Based on the simplified plastic theory, four formulas for flexural capacity in the negative moment area of continuous composite beams were given corresponding to the different depth of neutral axis and the different extent of shear connector.