多维地震作用下高柔结构的地震响应

Seismic Response of High-Flexible Structure Under Multi-component Ground Motion

研究了水平、摇摆和竖向地震动耦合作用下高柔结构的地震响应.推导了水平、摇摆和竖向地震动耦合作用下的动力方程,方程中考虑了摇摆地震动导致的基础转角位移产生的附加重力二阶效应,并探讨了竖向地震作用对重力二阶效应的影响.以某210 m高的电视塔结构为原型,进行了水平、摇摆和竖向地震动耦合作用下的缩尺模型振动台试验.理论与试验结果对比表明:振动台试验结果与推导的动力方程理论分析结果基本吻合,验证了理论分析的合理性和准确性;竖向地震动不仅会引起常规的重力二阶效应的变化,对摇摆倾斜位移引起的附加重力二阶效应也有较大的影响;在水平、摇摆和竖向地震动耦合作用下,结构的动力响应与单一的水平地震作用相比,不仅几何刚度随时间变化,而且会导致较大的不对称的位移响应,使得原本满足水平地震作用下抗震需求的结构可能发生破坏甚至倒塌.

In this paper , the seismic response of the high-flexible strj icture under coupled verical ground motion is investigated. First , a dynamic equation under the coupled ground motion is derved , inwhich the additional second-order effects of gravity caused by the foundation taken into consideration. Then , the influence of the vertical ground motion on the second-order effects of gravity is discussed. Finally , by taking a 210 m television tower as the prototype , the shaking table test of a reduced scale model is canied out under the coupled ground motion. The comparson between the theoretical analysis results andthe test ones show that （ 1 ） the results of the shaking table test accord well with the theoretical ones obtained through the derved dynamic equation , which testifies the rationality and accuracy of the theoretical analysis; （2） the verical ground motion can cause the change of the conventional second-order effects has an significant impact on the additional second-order effects of gravity caused by the tilt; and （3） as compared with the single horzontal ground motion , the coupled ground motion causes the geometric rigidity to change with time and results in a larger asymmetric displacement , which means that the strjicture capable of resisting the hor-zontal ground motion originally may get destroyed.