张力腿基础刚度对大跨浮式悬索桥风-浪动力响应的影响

采用张力腿基础的大跨度浮式桥梁是一种新型跨海桥梁体系，由于张力腿结构横向刚度弱，风-浪作用下结构响应受基础设计的影响大。该文构建了浮式桥梁风-浪荷载计算及结构运动响应有限元分析方法，以某采用张力腿基础的浮式悬索桥为对象，分析了张力腿基础淹没深度、张力腿拉索倾角等设计参数对张力腿基础横、竖向刚度以及风-浪作用下浮桥动力响应的影响。结果表明，风荷载对浮桥主梁的动力响应起主导性作用；通过增加张力腿基础的淹没深度增大结构的竖向刚度，能直接有效地减少大跨浮桥的动力响应；调整张力腿拉索倾角为75°～80°时可以有效降低结构的横、竖向运动响应，过小的倾角虽然可以提供较大的横向刚度，但会增大主梁的运动响应。因此，张力腿基础刚度是大跨浮式桥梁结构动力响应的控制性因素，应对基础设计参数开展重点研究。

Effect of tension leg foundation stiffness on dynamic responses of a long-span floating suspension bridge under wind and wave loads

The long-span floating bridge supported by tension leg foundations is a new type of sea-crossing bridge structure. The tension leg foundation significantly affects the structural responses under the wind and wave loads due to its weak lateral stiffness. This paper proposes the wind-wave load calculation of floating bridges and the finite element analysis method of structural motion response. A floating suspension bridge with a tension leg foundation is taken as an example. The effects of the design parameters of the tension leg foundation, such as the foundation flooded depth and the angle of tension leg cables, on the lateral and vertical stiffness and the dynamic responses of the structure under the wind and wave loads, are analyzed. The main conclusions can be drawn as follows: 1) The wind load dominates the response of the girder of a floating bridge; 2) The vertical stiffness can be improved by increasing the foundation flooded depth, so the motion responses of the long-span floating bridge can be reduced; and 3) the lateral and vertical motion of the structure can be reduced effectively when the inclination angle of tension legs is between 75°～80°. The inclination angle can increase both the lateral stiffness and the main girder’s motion response. The stiffness of the tension leg foundation dominates the dynamic response of the long-span floating bridge structure and should be focused in the structural design.