Study On Flexural Behavior Of Composite Beams With U-shaped Steelsection

The composite beams with U-shaped steel section are developed based on the traditional steel I shape composite beams. The U-shaped steel section can be rolled, or welded with steel plates. The shear connectors are welded on the top of U-shaped steel section. After pouring the concrete, the shear connectors can make the steel shape and concrete slab work together. Comparing with traditional steel I shape composite beams, the composite beams with U-shaped steel section have the advantages, such as higher loading capacities, higher fire resistance, better ductility, faster construction speed and so on. This kind of new composite beams have abroad application prospect. The bending behavior of composite beams with U-shaped steel shape is studied in this paper. The main works are as follows:(1) Six full-scale composite beams with U-shaped steel section were fabricated and tested. The influence of shear connector members, section dimensions and width of concrete slab on the bending behavior of composite beams is studied. Based on the experimental data and experimental phenomena, the detailed data including load, deflection, strain are analyzed.(2) The finite element software ABAQUS is used to develop the model to analyse the flexural behavior of the composite beams with U-shaped steel section. By comparing with the experimental results, the accuracy of finite element results is validated. Then the typical composite beams are analyzed to study its working mechanism. At last, the influence of residual stress, material strength and section dimensions on the bending behavior of composite beams is analyzed.(3) Based on the plastic design method, the formula for calculating the bending capacities of composite beams with U-shaped steel section are proposed, whose accuracy is validated by comparing with experimental results. This formula can be used in full shear connection composite beams and partial shear connection composite beams. Also, the formula for calculating the deflection is proposed based on the reduced rigidity method.