基於FEMA P58法之區域韌性評估：以美國洛杉磯非韌性鋼筋混凝土構架為例

Regional evaluation of resilience based on FEMA P58: a case study for nonductile reinforced concrete frames in Los Angeles

陳鵬宇(Peng-Yu Chen) ； Ertugrul Taciroglu

《結構工程》 38卷1期 (2023/03) Pp. 118-134

https://doi.org/10.6849/SE.202303_38(1).0005

摘要

都會地區房屋密集，遭遇地震時產生之性能表現係決定災損之重要依據。然而既有之結構性能評估所採用之非線性靜力法為一定量式分析（deterministic），一來無法有效地將地表運動以及結構動態反應之不確定性納入，二來其結果以結構反應參數來評估其耐震力，不利於非具工程背景之業主進行決策。另一方面，近來國際上朝向發展韌性城市（resilient city），對於結構工程師而言，如何量化房屋受震後之韌性以及進行大範圍之區域評估尚不清楚。有鑑於此，本研究提出一區域韌性評估之架構，當中依據機率式地震風險評估法（即FEMA P58），將增量動力分析與蒙地卡羅模擬結合進行災損評估，並依據評估結果量化成韌性指標（resilient index）。為示範此架構之應用，本研究以美國洛杉磯地區之非韌性（nonductile）鋼筋混凝土構架為例，透過開發之自動化建模程序完成1,452棟房屋之災損及韌性評估，當中完成了95萬筆非線性動力歷時分析。評估結果顯示在最大考量地震下的平均損失比為37.3%，震後近一年的平均韌性指標不到50%，且所有房屋恢復其原有功能需要至少三年時間。本研究藉由此案例說明，介紹FEMAP58法應用於區域評估之流程，後續期望能將此架構本土化應用於災前評估與災後應變，來提升台灣的都市韌性。

關鍵字

機率式地震風險評估 ； 區域評估 ； FEMA P58 ； 非韌性鋼筋混凝土構架 ； 增量動力分析 ； 韌性指標

並列摘要

Seismic damage and loss assessment are highly related to buildings' performance. However, the current nonlinear static analysis for performance evaluation is a deterministic methodology, where the uncertainties and variation of ground motion and numerical modeling cannot be considered. Furthermore, the outcome of engineering parameters is difficult to be utilized by decision-makers who may not have engineering backgrounds. While the world is toward developing resilient city, it is still not clear to structural engineers how to quantify the seismic resilience and evaluate it for large-scale regions. Hence, this research proposes a framework for regional resilience evaluation, which is based on probabilistic seismic assessment (i.e., FEMA P58) to incorporate incremental dynamic analysis and Monte Carlo simulation for damage and loss assessment. Moreover, the outcome of the regional evaluation is used to quantify the resilience index to illustrate the ability of a city for recovering from an earthquake. To demonstrate the application of the proposed framework, 1,452 nonductile reinforced concrete frames in Los Angeles are simulated by developing an automatic modeling program. Around 950,000 nonlinear time history analyses are conducted through a supercomputer, and the outcomes are used for loss estimation and resilience quantification. The results show that the mean loss ratio for nonductile frames under maximum-considered earthquake is 37.3%, and the resilience index indicates that the city needs at least 3 years to recover. While the presented work is a US-based case study, the authors hope the framework can be extended and localized for Taiwan's development of resilient city.

並列關鍵字

Probabilistic seismic assessment ； regional evaluation ； FEMA P58 ； nonductile reinforced concrete frames ； incremental dynamic analysis ； resilient index

參考文獻

FEMA P-58. (2012). “Seismic performance assessment of buildings.” Federal Emergency Management Agency.

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Applied Technology Council. (1985). “Earthquake damage evaluation data for California.” Applied Technology Council.

FEMA HAZUS-MH. (2003). “MR3 Technical Manual: Multi-hazard loss estimation methodology earthquake model.” Federal Emergency Management Agency.

Zeng, X., Lu, X., Yang, T.Y. and Xu, Z. (2016). “Application of the FEMA-P58 methodology for regional earthquake loss prediction.” Natural Hazards, 83(1), pp.177-192.