Experiment on seismic performance of new type railway pier with ductile structure in strong earthquake area

Abstract:

In order to improve the ductility seismic performance of railway piers in high intensity seismic regions, then reducing the internal force at the bottom of piers under strong earthquakes and protecting the pile foundations, this paper presents two new ductile structure schemes for railway pier. And low cyclic loading tests were carried out on a prototype pier model specimen and two new pier model specimens with ductile structure. Finally, the damage behavior, failure mechanism, hysteretic performance, energy dissipation capacity, residual displacement, stiffness degradation characteristics and strength degradation characteristics of different piers were analyzed. The test results show that the failure mode of round-ended hollow pier commonly used in railway is mainly bending failure. In the plastic hinge area at the bottom of the pier, a large number of cracks develop, concrete flake off, stirrups are exposed, and some longitudinal reinforcement fracture. But the failure modes of two new piers with ductile structure are closer to the corner failure of the rocking pier. Their failure area is mainly concentrated in the range of 20 cm at the bottom of the piers. By the end of the tests, only six to nine horizontal cracks appear on the piers, and partial concrete at the edge of the piers bottom is crushed and peeled off. The initial stiffness of the new piers with ductile structure can be consistent with that of the prototype pier to meet the stiffness requirements of railway piers and ensure the operation safety of trains. The equivalent yield forces of the new piers 2 and 3 are 91.31% and 77.12% of that of the prototype pier, and the ultimate horizontal forces at the top of the piers are 72% and 65% of that of the prototype pier. The internal forces of pier bottom and pile foundation in the new piers with ductile structure can be effectively reduced under strong earthquakes, thus protecting the pile foundation. The equivalent viscous damping ratios of the new piers are more than 50% of that of the prototype pier, and the ductility seismic performance of railway round-ended hollow pier is improved through new ductile structure schemes.