- 學位論文
頂層加蓋建物性能式耐震評估
Performance-Based Earthquake Assessment of Rooftop Surcharges to Existing Buildings
摘要
1999年921集集大地震震出台灣建築物許多問題，在台灣地區民間住宅，許多住戶為了貪圖使用空間及便利性，而私自變更原先結構設計，將建築物頂層加蓋一層或二層，雖然加蓋之後並不會造成建築物有立即危險，但是加蓋後對結構體的強度、勁度、耐震能力等卻有顯著不良的情形，由921地震後可發現低矮建築物因為頂層加蓋造成房屋塌陷的例子不勝枚舉。本文即針對此情況，加以分析探討，採用ATC-40容量振譜法，並利用SAP2000軟體進行非線性靜力分析(推覆法分析)，求得建物之容量曲線，考慮不同回歸期的需求曲線，找出各個回歸期下的功能點，依據功能點比較建築物在加蓋前後的塑鉸分佈情況、頂層變位角及各樓層間變位角的變化，並利用計算出的層間變位角進行檢核，檢核加蓋前後是否滿足其性能水準；本文亦進行非線性動力分析，使用921集集大地震時收集到的時間歷時資料，依據Vision 2000建議之設計目標所規定的地震等級，調整時間歷時資料的PGA值進行分析，檢核各樓層層間變角是否滿足Vision 2000規範中的性能水準。由本文分析結果得知，當建築物加蓋後層間變位角明顯增加，加蓋後的建物無法滿足規範規定之性能水準。
並列摘要
Numerous buildings with the penthouse-surcharges on top floor are often present for the convenience of utility in Taiwan. Although such illegal structures may not cause immediate dangerousness, the surcharges will affect seriously on the strength, stiffness and earthquake-resistant capacity of the buildings. The low-rise construction with the surcharges were extensively collapsed and damaged for the 921 Chi-Chi Earthquake in Taiwan. Hence, the main of this study is to use capacity spectrum method and SAP2000 program to carry out static nonlinear analysis, i.e., the pushover method. After static nonlinear analysis, we can obtain capacity demand curves of different regressions and performance points. According to performance points, one can compare those with plastic hinge locations, roof displacements, interstory drifts and check if the interstory drifts satisfy the performance level or not. We also adopt time-history dynamic nonlinear analysis, based on Vision 2000 criterion with changing the PGA to carry out the analysis. The calculations of the maximum roof drift ratio and interstory drift ratio of the buildings with surcharges are compared with those of the original one without any surcharges. The results appear that the interstory drift ratio of illegal structures cannot satisfy the specifications on the seismic design code.