1. School of Civil Engineering，Southwest Jiaotong University，Chengdu 610031，China;
2. National Engineering Laboratory of Geological Disaster Prevention Technology in Land Transportation，Southwest Jiaotong University，Chengdu 610031，China
Abstract：To study the seismic failure mode and dynamic response characteristics of round-ended hollow tall piers in railway engineering under different levels of earthquake，taking a typical single-track railway round-ended pier with the height of 40 m as the research object. The shaking table tests of three 1/6 scaled pier models were carried out，and the test results were compared with those of similar specimens by semi-static tests. The results show that great differences exist in seismic failure modes of the two kinds of specimens. Under the same tip drift ratio，the cracks of specimens under dynamic loading distribute along the whole pier body，while those of quasi-static ones mainly concentrate within the 2/3 of the pier height. In addition to the obvious plastic zone formed around the internal chamfering of dynamic specimens，there are still relatively dense cracks in the pier middle and upper part. It indicates that the higher-mode effects occur and act as the potential region of plastic hinge for the round-ended hollow tall piers. With the increase of input PGA，the damping ratio，acceleration，displacement，and strain responses increase，while the vibration frequency and dynamic amplification coefficient at pier top decrease owing to the damage accumulation. The pier specimens appear cracks under the PGA between 0.15g to 0.20g，yields between 0.45g～0.5g for the first time，emerges equivalent yielding at 0.55g or 0.60g，and enters into the nonlinear state under the final seismic excitation (PGA=0.8g or 0.9g) with drifts among 1.18% to 1.48%Finally，the specimen DB-2 (ρs=1.268%) owns the most excellent ductility performance under rare earthquake，then the 0.630% specimen DB-1，yet the DB-3 (ρs=0.270%) has the poorest ductility due to brittle failure.
