不同承台结构形式对大跨刚构桥抗震性能的影响分析

为探究高烈度区不同承台结构形式对大跨预应力混凝土连续刚构桥梁抗震性能的影响，以某座108 m+188 m+108 m双幅双肢薄壁墩连续刚构桥为工程背景，采用时程分析方法对该桥进行三向激励，对比研究纵联横离式、纵联横联式、纵离横离式、纵离横联式共4种承台结构形式对两幅桥墩柱和桩基内力、位移动力响应的影响。结果表明：采用纵离的承台形式在纵向地震下，桩基内力需求降低了30%~70%，墩柱内力需求降低了26%~33%，且与纵联的承台形式相比，桩身拉力减少较多；采用横联的承台形式在横向地震下，桩身轴力需求降低11%，且基本不存在拉力，桩基和墩柱的内力响应虽分别增大30%和16%，但与纵向减小量的相比，增加幅度较小。因此，为提高特大桥全寿命周期的安全性和经济性，对于以地震响应为控制设计核心要素的高烈度区大跨连续刚构桥梁，建议采用纵离横联式的承台结构形式。

Analysis of Influence of Different Base Slab Structures on Seismic Performance of Long-span Rigid-frame Bridge

In order to explore the influence of different base slab structural forms on the seismic performance of long-span prestressed concrete continuous rigid-frame bridges in high intensity areas, taking a (108+188+108)-m double-width double-leg thin-walled pier continuous rigid-frame bridge as the engineering background, the time-history analysis method is used to carry out the three-dimensional excitation on the bridge. The influences of four base slab structural forms, namely, the longitudinal and horizontal separation, the longitudinal and horizontal connection, the longitudinal separation and horizontal separation, and the longitudinal separation and horizontal connection on the internal force and displacement dynamic response of the double-width pier columns and pile foundations are compared and studied. The results show that under the longitudinal earthquake, the internal force demand of pile foundation is reduced by 30%~70%, and the internal force demand of pier column is reduced by 26%~33% if the longitudinal base slab is used. And compared with the longitudinal connection of base slab, the pile body tension is reduced more. Under the transverse earthquake, the axial force demand of the pile body is reduced by 11% if the horizontal connection of base slab is used, and there is basically no tension. The internal force response of the pile foundation and the pier column increases by 30% and 16% respectively, but compared with the longitudinal reduction, the increase is small. Therefore, in order to improve the safety and economy of the whole life cycle of the super-large bridge, for the long-span continuous rigid-frame bridge in the high intensity area with the seismic response as the core element of the control design, it is proposed to adopt the longitudinal separation and horizontal connection structural form of base slab.