矩形中空鋼管柱之耐震性能與寬厚比限制

Abstract

中空鋼管柱斷面(HSS)是一種經冷加工處理製成之結構用柱，其特殊的製造過程使其相較於傳統的I型柱與箱型柱(BOX)在生產成本與碳排放上更具優勢，是結構用柱的理想選擇。 寬厚比是影響鋼管柱產生局部挫屈的重要參數，透過限制寬厚比可確保鋼柱的耐震性能。然而我國、美國與日本對HSS的寬厚比之限制存在顯著差異，且目前針對矩形HSS柱耐震行為之相關研究尚不充分。 本研究設計五支矩形HSS試體，進行承受軸力並施加反覆側向位移之試驗，旨在探討銲道位置、翼板寬厚比b/t以及軸力比P/P_ya對於HSS耐震性能之影響，並以極限層間位移角〖SDA〗_cr作為性能參數。試驗結果顯示，銲道位置對〖SDA〗_cr影響並不顯著，b/t與P/P_ya對〖SDA〗_cr呈現負相關。 隨後本研究選用廣泛應用於日本工程實務之兩種HSS斷面(BCR295與BCP325)利用有限元素軟體進行參數分析，同時針對矩形試體進行模擬驗證，以確認模型能夠反映矩形HSS受軸力與反覆位移作用下之力學行為。此外，為確保HSS矩形柱在受弱軸方向地震力時仍具良好的耐震性能，本研究參數分析除對強軸方向進行反覆位移，亦進行弱軸方向之反覆位移之參數分析。參數分析結果顯示，在強軸方向下，除b/t與P/P_ya對〖SDA〗_cr有影響外，高深比L/H、斷面寬深比B/H以及材料降伏比YR對〖SDA〗_cr也有一定的影響；而在弱軸方向下，腹板寬厚比h/t、P/P_ya、L/B與YR對〖SDA〗_cr有影響。 參照b/t、L/H等幾何參數範圍，本研究建立強軸與弱軸之數據庫，並根據參數分析結果，針對強、弱軸數據庫將對應之重要參數加入迴歸式中，以確保迴歸式能夠有效預測〖SDA〗_cr。最終，本研究依據B/H不同，使用不同迴歸式以評估矩形HSS柱之耐震性能。 透過迴歸分析結果可提出HSS之耐震寬厚比建議限制式，並與我國、美國及日本之現行規範做比較，結果顯示，我國與美國規範在低軸力下較為保守、高軸力下則較為寬鬆，日本規範整體則過於寬鬆。結果可做為未來耐震設計規範之參考依據。

Hollow Structural Section (HSS) columns are steel members manufactured through cold-forming, offering advantages over I-shaped and built-up box columns in terms of production cost and carbon emissions, making them well-suited for structural applications. However, significant differences exist in the specified width-to-thickness ratio requirements for HSS among Taiwan, the United States, and Japan, while current research on the seismic behavior of rectangular HSS columns remains insufficient. Five rectangular HSS specimens were designed and tested under axial load and cyclic lateral displacement to investigate the effects of weld seam location, flange width-to-thickness ratio b/t, and axial force ratio P/P_ya on seismic performance. The critical story drift angle 〖SDA〗_cr was adopted as the performance parameter. Test results indicate that the location of the weld seam had minimal influence on 〖SDA〗_cr, while both b/t and P/P_ya exhibited a negative correlation with it. Finite element models were subsequently developed and validated against experimental results. Parametric studies were then conducted on two widely used HSS sections in Japanese practice (BCR295 and BCP325). To evaluate seismic performance under different loading directions, cyclic displacements were applied along both strong and weak axes. The results indicate that, the SDA_cr was influenced by b/t, P/P_ya, span-to-depth ratio L/H, section aspect ratio B/H and yielding ratio YR. In contrast, for the weak-axis direction, SDA_cr was primarily affected by h/t, P/P_ya, L/B and YR. Based on the range of b/t and L/H, separate databases for strong-axis and weak-axis loading were established in this study. To ensure that the regression models can accurately predict the SDA_cr, the parameters identified as influential to SDA_cr were incorporated into the regression equations. Depending on the value of B/H, different regression models can then be applied to evaluate the seismic performance of rectangular HSS columns. Finally, seismic width-to-thickness ratio requirements for HSS columns are proposed based on the regression results and compared with the current code in Taiwan, the United States, and Japan to assess their adequacy and support future design guidelines.