鋼構建築物之生命週期成本與永續性分析

Abstract

近年來對於環境保護議題之討論興起，根據聯合國統計，建築與營造部門所產生之二氧化碳年碳排量占全球之38%。且通常營造商進行決策時僅考慮建築之建置成本，為了實現長期經濟效益，針對建築物之生命週期成本與碳排放的討論逐漸受到重視。而鋼結構建築由於其重量輕、易於施工與延性(ductility)強等優點，被廣泛地用於頻繁發生地震與人口密集地區中。而台北盆地地區地質複雜、人口密度高，且鄰近山腳斷層，為了應對未來可能發生之近斷層地震風險與調查台北盆地地區內鋼構建物之主體結構壽命生命週期五十年內由地震導致之經濟與環境影響，有必要詳細，以作為相關決策者之參考依據。 為深入了解並比較各種不同鋼結構系統於此類地震事件中之耐震能力，本研究回顧有關於近斷層地震特性與鋼結構對於近斷層歷時下反應之相關文獻，並使用不同樓高之鋼結構抗彎矩構架(MRF)、二元構架(DUAL)、周緣抗彎矩構架(PMF) 與周緣挫屈束制斜撐構架(PBRB)作為構架原型進行震損評估。本研究依據美國 FEMA P-58 所提出之評估流程，使用修繕金額與碳排放量作為指標來量化鋼構建築物之震災韌性，並採用有限元素軟體 LS-DYNA 針對三種原型構架進行非線性動力歷時分析，進行基於近斷層情境與基於整體危害度之震損評估，以探討不同結構系統之鋼構建築物於山腳斷層發生規模7.3之近斷層脈衝地震下之震損情形與其年化修繕、碳排成本評估。 結果顯示，本研究所考慮的原型構架均滿足ASCE 7-16對於50年內倒塌風險的要求。震災損失評估結果表明，非結構構件的修復損失是主要的震損來源，若以經濟性和永續性作為考量，應優先考慮降低各系統的樓層加速度。此外，結構週期差異對生命週期成本有顯著影響，且使用經濟性耐震指標時須注意構件損毀樓層的影響。若以生命週期成本與碳排放作為主要考量，建議在中樓層、高樓層及超高樓層分別選擇MRF、PMF和BRBF作為鋼結構建築使用之系統。近斷層震損評估結果則顯示，在中高樓層建築中亦可使用PBRB系統，以降低震災損失並提升空間使用靈活性，但需對另該系統進行生命週期成本分析以評估其效益。

Environmental protection efforts have highlighted the construction sector's significant CO2 emissions, contributing 38% of global emissions annually according to the United Nations. Typically, builders focus on construction costs, overlooking long-term economic and environmental impacts. Steel structures, favored for their light weight, ease of construction, and high ductility, are crucial in earthquake-prone and densely populated areas. Given the intricate geology and dense population of the Taipei Basin, and its proximity to the Shanchiao Fault, evaluating the 50-year economic and environmental impacts of seismic events on steel structures is vital for informed decision-making. This study assesses seismic damage in various steel structural systems—Moment Resisting Frames (MRF), Dual Systems (DUAL), Perimeter Moment Frames (PMF), and Perimeter Buckling Restrained Braced Frames (PBRB)—at different heights. Using FEMA P-58 evaluation procedures, repair costs, and carbon emissions quantify seismic resilience. Nonlinear dynamic time-history analyses with LS-DYNA evaluate seismic damage under near-fault scenarios, focusing on a magnitude 7.3 earthquake at the Shanchiao Fault. Annualized repair and carbon emission costs are assessed for different structural systems. Results show that all prototype frames meet ASCE 7-16 collapse risk requirements within 50 years. The seismic loss assessment results show that the repair costs for non-structural components are the main source of seismic losses, priority should be given to reducing floor accelerations in various systems. Additionally, differences in structural periods significantly impact life cycle costs, and when using economic seismic indicators, attention must be paid to the impact of damaged floors. Suppose life cycle costs and carbon emissions are the primary considerations. In that case, it is recommended that MRF, PMF, and BRBF be selected for mid-rise, high-rise, and super-high-rise steel structures, respectively. Near-fault seismic loss assessment results indicate that PBRB systems can also be used in mid-rise and high-rise buildings to reduce seismic losses and improve space usage, but a life cycle cost analysis should be conducted to evaluate the benefits of this system.