含消能阻尼器之制震結構耐震能力評估方法研究

Abstract

有鑒於九二一地震的慘痛教訓，制震設計的概念已漸為國內業者接受，利用各種型式的阻尼元件來消散地震能量也蔚為風潮。目前國內工程界多採用內政部建築研究所於1999 年公佈的「鋼筋混凝土建築物耐震能力評估法與推廣」﹙簡稱強度韌性法TS-RC﹚作為建築物耐震能力評估的依據，惟其並未考慮結構物加裝阻尼器之條件。鍾立來等人修正TS-RC法，可利用迭代方式求取含位移型阻尼器結構之崩塌地表加速度。與ETABS程式根據美國ATC-40所發展之推覆分析法之耐震評估結果比較，利用TS-RC法推估之結構崩塌地表加速度有偏低的傾向，顯與九二一地震之結果不符。因此，本研究擬嘗試採用推覆分析法，考慮結構加裝位移型阻尼器﹙含鋼框架﹚之條件下進行耐震能力評估分析，期能提供結構工程師一套簡便的「制震結構耐震能力評估方法」。本文以一現存建築物之耐震補强設計為例，分別根據TS-RC法及推覆分析法完成建築物補强前、後之耐震能力評估。結果顯示，TS-RC法估算之崩塌地表加速度值確有偏低的情況，而推覆分析法於制震結構所得的耐震容量曲線部分區段則出現不連續的現象，並不合理，現有ETABS軟體內建之推覆分析模組尚無法適當反映出制震結構的崩塌地表加速度。

In response to the disastrous lessons from Chi-Chi earthquake, the concept of seismic energy dissipation design has been gradually accepted by domestic industries. Utilization of a variety of damping devices for seismic energy dissipation has become a trend. Currently the “Seismic Capacity Assessment Method for RC Structures (1999)” (referred to as the strength ductility TS-RC method herein) by the Architecture Research Institute, Ministry of Domestic Affairs has been most widely adopted by the engineering professions. However, it does not take into account structures with supplemental seismic dampers. A modified TS-RC method with an iterative procedure by Chung et al. may used to determine the collapsing peak ground acceleration (CPGA) of the structure with displacement-dependent dampers. By comparing the results by ETABS pushover analysis based on ATC-40 of the United States, it is found that TS-RC method tends to underestimate the CPGA, which obviously contradicts to what have happened in Chi-Chi earthquake. Therefore, this study tries to adopt the pushover method for seismic capacity assessment of structures with seismic dampers (including the added steel frame), meant to provide for engineers a simple tool for seismic capacity assessment of structures with energy dissipative dampers. Using a practical seismic retrofit project as example, this study conducts seismic capacity analyses of the target structure prior to and after retrofit, using both the TS-RC and pushover methods independently. Results indicate that, the TS-RC does underestimate the CPGA (of the non-retrofit structure), while the seismic capacity curve of the seismically damped structure derived by the pushover analysis irrationally exhibits discontinuity in some segments of the curve. The built-in pushover analysis module of the current ETABS software cannot yet adequately reflect the CPGA of seismically damped structures.