- 期刊
典型校舍耐震性能與易損性曲線探討
A STUDY FOR THE SEISMIC PERFORMANCE AND FRAGILITY CURVE OF A TYPICAL SCHOOL BUILDING
摘要
目前國內既有典型校舍多使用基於容量震譜法的非線性側推分析做為詳細評估方法，以評估所得之性能目標地表加速度與場址475年設計地震最大地表加速度比較，作為結構耐震能力是否足夠之依據。FEMA 440顯示容量震譜法於相對短週期結構物的評估結果過於保守。本文即以一棟典型的校舍建築為範例，以增量式動力分析(IDA)探討典型校舍的耐震能力與容量震譜法的保守程度，並進一步由IDA分析結果建立範例校舍的易損性曲線，檢視在評估所得之性能目標地表加速度地震作用下，建築物倒塌的機率。結果顯示對於三層樓典型校舍案例結構，容量震譜法隱含有2.25的安全因子；於耐震評估所得之性能目標地震作用下，案例結構呈現結構不穩定狀態之發生機率為5.3%，屬於可接受範圍，因此評估設定的性能目標應為合理。
並列摘要
At present, pushover analysis based on the capacity spectrum method is often used for the detailed seismic evaluation of existing typical school buildings in Taiwan. The performance-target ground acceleration is compared with the site's peak ground acceleration (PGA) for a design earthquake with a 475-year return period in order to evaluate whether the seismic capacity is sufficient. However, as stated in FEMA 440, the results of the evaluation are too conservative for relatively short-period structures. In this paper, incremental dynamic analysis (IDA) of a typical school building is used to study its seismic capacity and how conservative is the capacity spectrum method. Additionally, from the results of IDA, a seismic fragility curve of a sample school building can be built in order to evaluate the probability of collapse of this building under an earthquake with the evaluated performance-target PGA. From the analysis results, the roof displacement estimated by the capacity spectrum method is on average 2.25 times the value from nonlinear dynamic analysis for a typical three-story school building; under the performance-target earthquake for seismic evaluation, this structure has a 5.3% probability of collapse, which is acceptable, and the specified performance target is a reasonable and conservative choice.