SEISMIC BEHAVIOR OF PORTAL BOX-SHAPED STEEL PIER WITH EMBEDDED ENERGY-DISSIPATING STEEL PLATES

Based on the design concept of earthquake resilient structure, a new-type of portal box-shaped steel pier with embedded energy-dissipating steel plates was proposed. The quasi-static tests of 6 portal box-shaped steel pier specimens under variable axial pressure and cyclic horizontal loading were carried out. By analyzing the failure mode, load-displacement hysteretic curve, skeleton curve, displacement ductility coefficient, stiffness degradation characteristics, strength degradation coefficient and cumulative hysteretic energy, the effects of installation of energy-dissipating steel plate, and axial compression ratio and thickness of energy-dissipating steel plates on the seismic performance of the new-type portal steel piers were discussed. The finite element models of portal steel bridge piers were established, and the simulation results are in good agreement with the experimental results. The results show that the installation of energy-dissipating steel plate can improve the ductility, deformation capacity and energy-dissipating capacity of portal box-shaped steel piers, and can effectively delay buckling deformation and cracking of wall plates. The steel plate near the bolt hole of the wall plate at the root of the new-type of portal box-shaped steel pier is easy to crack due to stress concentration, resulting in the rapid reduction of the maximum bearing capacity of the specimens. The bearing capacity, energy-dissipating capacity and earthquake-resilient capacity of the specimens increase with the increase of axial compression ratio. A smaller thickness of the replaceable energy-dissipating steel plates leads to smaller bearing capacity and faster stiffness degradation of the specimens, as well as improved ductility and energy-dissipating capacity of the specimens. The axial compression ratio and the thickness of the energy-dissipating steel plate have relatively little effect on the strength degradation of the specimens. In order to facilitate the application of this new-type portal steel pier, a simplified formula for evaluating ductility and a seismic design formula for calculating bearing capacity of the portal box-shaped steel pier with embedded energy-dissipating steel plates were proposed based on the experimental results.