Shear performance test and nominal bearing capacity on the transfer beams of steel reinforced concrete in subway station structure

Abstract

To investigate the shear behaviors of steel reinforced concrete (SRC) transfer beams in subway station structure, the shear performance tests of 13 specimens on the transfer beams were investigated under the concentrated loads. The design parameter variables of transfer beams in the experiments main included the shear span ratio, profile steel ratio and section form of profile steel. The failure modes, load–displacement curves and strain characteristics of transfer beams were also analyzed in detail. The results show that the vertical cracks appeared in the transfer beams firstly, then the main oblique cracks appeared on both sides of the middle span of transfer beams, and finally the concrete at the support and the loading point of transfer beams fell off due to the shear action, which was a typical shear failure. Compared with reinforced concrete (RC) transfer beams, the shear bearing capacity and ductile deformation ability of SRC transfer beams have been significantly improved, and the shear bearing capacity of SRC transfer beams is 112.05% higher than that of RC transfer beams at the same shear span ratio. Reducing the shear span ratio can enhance the shear bearing capacity of transfer beams, but it is not good for their ductility. With the profile steel ratio from 5.41 % to 5.89 %, the shear bearing capacity of channel steel reinforced concrete transfer beams and I-shaped steel reinforced concrete transfer beams increases by 11.81 % and 12.14 % respectively. However, the section form of profile steel has less influence on the shear behavior of transfer beam. According to the mechanical properties and failure mechanism of SRC transfer beams, the calculation formulas on the shear bearing capacity of SRC transfer beams was proposed based on the truss-arch model. The calculation accuracy on the modified formulas of SRC transfer beams were evaluated by the comparison between the calculated values and test values.