平面不规则复杂超限结构振动台试验研究

Shaking table test of a complex transfinite structures with plane irregularity

以实际工程为背景,对平面不规则复杂超限结构进行地震模拟振动台试验研究,量测模型结构动力特性、阻尼比及其在不同水准地震作用下加速度、位移等动力反应,研究结构破坏机理及模式。试验结果表明,模型结构X方向经历7°多遇及基本烈度地震后基本保持弹性状态。结构X向一阶自振频率为5.610 Hz,阻尼比2.995%;Y向一阶自振频率5.484 Hz,阻尼比2.478%,随加速度幅值的增加自振频率逐渐降低,阻尼比提高;罕遇地震作用后模型结构Y向自振频率较震前下降约15%,阻尼比提高至6.531%,7°多遇地震下结构X、Y向最大层间位移角分别为1/1071,1/799,罕遇地震下结构最大层间位移角为1/120,均满足规范要求。多遇地震Kobe波激励下结构上部楼层最大位移比达1.331,存在一定扭转不规则,但程度较小。试验表明原型结构设计基本合理,整体抗震性能较好。并对原型结构设计提出建议。

A shaking table test of complex transfinite structure with plane irregularity was carried out under the backdrop of a practical project. The dynamic characteristics and damping ratio were examined,together with the vibration acceleration and displacement under different seismic intensities. The failure mechanism and failure modes of the structure were studied in detail. The experiment results show that the model structure is still in elastic state under frequently occurring and basic intensity earthquake in X direction. The fundamental natural frequency and damping ratio of the model structure in X direction is 5. 610 Hz and 2. 995%,and that in Y direction is 5. 484 Hz and 2. 478% respectively. Along with the increase of the acceleration amplitude,the natural frequency of model structure reduces while the damping ratio increases. The natural frequency of model structure reduces by 15% and the damping ratio increases to 6. 531% under the rare earthquake. The maximum inter-story drift ratios of the model structure in X and Y direction are 1 /1071 and 1 /799 under the frequently happening earthquake of 7 degrees,as well as 1 /120 in Y direction under the rare earthquake. All the above ratios can meet the requirements in the design code. Under the action of Kobe wave of frequently happening earthquake,the upper floors＇ maximum displacement ratio reaches 1. 331 and an irregular torsional vibration with less intensity occurs. A rational structural design and good seismic behaviors of the practical project were approved by the test.Some suggestions were put forward according to the test and analysis results.