方形中空鋼管柱之耐震行為與寬厚比要求

Abstract

結構中空鋼管斷面(HSS)其強軸與弱軸方向的慣性矩與迴轉半徑相近，相較於傳統I型斷面鋼材，具有較大之抵抗側向力與軸壓能力，因HSS鋼柱利用特殊工法製成，如BCR295使用冷彎工法、BCP325利用冷壓工法，其焊接量和碳排放少，且可自動化大量生產，製造成本較低，因此HSS具有較佳之經濟效益及永續性，在性能與成本上皆有很大的優勢。 本研究以經驗證後之有限元素模型，評估HSS鋼柱於同時承受軸力和側向位移下之遲滯行為，納入完美之HSS鋼柱模型與保守考慮初始幾何缺陷之含缺陷HSS鋼柱模型，對BCR295與BCP325等鋼管柱斷面進行參數分析，斷面涵蓋廣泛的b/t與L/r，b/t涵蓋美國規範AISC341-22之 λ_hd與λ_md、我國LRFD規範之λ_pd、日本規範之FA。研究中定義最大彎矩處所對應之位移比為臨界層間位移角(SDAcr)，並綜合考慮邊界條件與位移歷時的效應，修正後得到有效臨界層間位移角(SDA’cr)，以量化鋼柱之耐震性能，最終透過迴歸分析得到影響鋼柱性能之參數關係式，探討初始缺陷之影響，並提出建議之寬厚比要求。 參數分析之結果顯示，軸力比(P/Pya)、長細比(L/r)、寬厚比為影響SDA’cr之關鍵參數，且寬厚比與P/Pya與SDA’cr呈現負相關，而L/r與SDA’cr呈正相關。比較完美HSS鋼柱模型與含缺陷HSS鋼柱模型，由迴歸式間差異探討初始缺陷之影響，缺陷對於HSS鋼柱之SDA'cr存在顯著負面影響，且隨著寬厚比增加，缺陷的影響明顯增加。 以迴歸分析結果提出可易於進行HSS鋼柱耐震設計之寬厚比要求，確保HSS鋼柱具有足夠之韌性。所提出之設計式亦與美國AISC 341-22、臺灣LRFD、日本FA等設計要求進行比較，評估各規範之適宜性，以作為未來耐震設計之參考及法規修訂之依據。這些結果不僅為HSS鋼柱之耐震設計提供有力數據支持，也為未來規範之修訂提供科學依據，推動HSS鋼管柱在實際工程中的應用。

Hollow Structural Sections (HSS) feature moments of inertia and radius of gyration that are similar in both strong and weak axes, providing greater resistance to lateral forces and axial compression compared to traditional I-shaped steel sections. HSS columns are manufactured using specialized methods, resulting in reduced welding and carbon emissions. These methods enable automated mass production, lowering manufacturing costs. Consequently, HSS offers superior economic efficiency and sustainability, with significant advantages in both performance and cost. This study uses a validated finite element model to evaluate the hysteretic behavior of HSS steel columns under combined axial force and lateral displacement. The analysis includes both perfect and imperfect HSS column models. A parametric analysis is conducted on BCR295 and BCP325 HSS columns, covering a wide range of width-to-thickness ratios and slenderness ratios (L/r). The displacement ratio corresponding to the maximum bending moment is defined as the critical story drift angle (SDAcr). By considering boundary conditions and displacement history effects, the effective critical story drift angle (SDA’cr) is calculated to evaluate the seismic performance. Regression analysis identifies key parameters, including the axial load ratio (P/Pya), slenderness ratio (L/r), and width-to-thickness ratio. Initial imperfections significantly impact SDA’cr increasing with width-to-thickness ratio. The study proposes width-to-thickness ratio requirements for seismic design to ensure HSS column ductility. The design equations are compared with AISC 341-22, Taiwan's LRFD, and Japan's FA standards, providing a basis for future seismic design and code revisions.