行波激励下二维框架结构地震响应分析

Earthquake Response Analyses of Plane Frame Structures under Wave Passage Excitation

目的研究短跨结构地震响应是否需要考虑行波效应.方法利用多点激励动力方程,针对四类场地地震波作用下的三跨三层钢筋混凝土和三跨六层钢-混凝土组合梁平面框架结构的地震响应进行研究,分析各柱的剪力和梁端弯矩.结果钢筋混凝土框架结构和钢-混凝土组合梁框架结构在第三、四类场地地震波作用下,考虑行波效应时,迎波方向的底层边柱剪力相对于一致激励出现显著增大现象,最大增加35%.第三类场地地震波作用下,行波激励下迎波方向的底层边跨梁梁端弯矩相对于一致激励出现显著增大现象,最大增加21%.结论短跨结构地震响应计算时不应一概忽略行波效应.

Two plane frame structures,one is a three-span,three-story reinforced concrete structure and another is a three-span,six-story steel-concrete composite beam structure,are adopted to study whether wave passage effect should be considered in the seismic responses of frame structures or not.Based on the equations of motion for a structure subjected to multiple support excitations,the earthquake responses of two plane frame structures to wave passage excitations and uniform excitations are computed respectively for each of four sites＇ seismic waves.The results of column shear forces and beam-end bending moments obtained from the wave passage excitations are compared with those of the uniform excitations.Numerical results showed that wave passage effect caused the shear force of the bottom-side column facing the seismic wave to increase remarkably for the plane frame structures being at site classes III and IV.The maximum increasing percentage is 35%.At site class III,wave passage excitation increased significantly the beam-end bending moment of bottom beam facing the seismic wave compared with the result of uniform excitation.The maximum increasing percentage is 21%.It demonstrated that the wave passage effects should not be overlooked in the earthquake response analyses even for short-span structures.