Earthquake Response Analysis Of Three-Directional Isolated Continuous Bridges

Seismic isolated bridge technique is an effective approach to improve seismic resistance performance of bridges which play a prominent role in the urban lifeline system. Theory analysis and experiment research are mainly performed domestically, but researches on multi-dimensional seismic action and three-dimensional seismic isolation technique are seldom investigated. A new three-dimensional seismic isolator is proposed in this dissertation and its seismic isolation effect is validated, influence of parameters, multi-directional seismic action, earthquake intensity and pile-soil-bridge dynamic interaction on earthquake response of continuous bridges and seismic isolation effect of the isolator. The contents of this dissertation are mainly as follows:(1)Many documents are consulted and some aspects such as seismic isolated bridges, multi-dimensional seismic action and multi-dimensional seismic isolation, soil-structure dynamic interaction and so on are sumerized briefly. The primary contents in this dissertation are presented.(2)A new three-dimensional seismic isolator consisted of disc spring and vicous damper in parallel firstly and then in series with Lead Rubber Bearing is proposed in this dissertation. This isolator is effective to resolve the difficulty in vertical capacity and vertical damping and can provide multi-dimensional appropriate stiffness and damping perfermence.(3)A three-dimensional finite element model of three-span continuous slab bridge is established on the base of rigid foundation assumption. Firstly, dynamic characteristics of continuous slab are analyzed. Then earthquake response of the bridge is calculated separately with earthquake response sperctra method and dynamic time-history analysis method, validating horizontal and vertical seismic isolation effect. Influence of factors such as parameters of the isolator, multi-directional seismic action, earthquake intensity on seismic isolation effect is studied. Results show that the three-dimensional seismic isolator has favorable horizontal isolation effect and better vertical isolation effect. Horizontal reduction efficiency will rise with the increase of the ratio of pre-yiled and post-...