九二一地震建築物破壞模式之探討—以三棟建築物為例

Abstract

本文主要在探討在九二一地震中，常見的兩種破壞模式：弱層效應的破壞與短柱破壞，這兩種因素的破壞都與牆有很密切的關聯。所作的分析，以三棟在九二一地震中破壞為例，除了依規範作靜力分析外，也取九二一地震的歷時資料作動力歷時分析，比較牆壁的加入對結構物的影響，進而找出其破壞模式。研究結果顯示，一樓形成弱層的結果，使一樓的柱受到相當大的彎矩，角柱部分更是承受了很大的軸力，建築物甲及建築物丙即因為這樣的因素而倒塌。建築物乙由於使用上的變更加入了矮牆，造成了部分的短柱，研究顯示這些短柱將承受較原先大二到三倍的剪力大小，因而造成剪力破壞的發生。

The main purpose of this thesis is to discuss two main failure patterns of three building structures in 921 Chi-Chi earthquake. The soft story effect and the short-column effect are the major reasons for the failure. These two effects are strongly related to the existence of walls. We perform static analysis and dynamic time history analysis for three real buildings （labeled A, B and C） collapsed in this earthquake in order to compare the result with wall effect and that without wall effect. The results show that the columns in the ground story will bear more moment under the condition that the ground story becomes soft story which means that the walls in ground floor failure first. And the columns in the corner will bear extremely large axis force. The building A and C are failed by this effect. For building B, some half-height walls are filled for some spans in ground floor to create short column effect. And we found that those short columns during earthquake will have to resist double, even triple of the shears which is the result without considering short column effect.