鋼骨鋼筋混凝土梁柱構材極限強度與韌性行為

Abstract

本研究藉由數值分析方法，探討鋼骨鋼筋混凝土 (Steel Reinforced Concrete，簡稱SRC) 梁柱構材承受純彎矩與軸力-彎矩載重之行為，由彎矩-曲率關係曲線圖探討混凝土受箍筋與鋼骨圍束於SRC構材極限彎矩強度與韌性行為之影響。分析模式中將SRC構材斷面受混凝土的圍束分為三種不同的區域：非圍束區混凝土、次圍束區混凝土與高圍束區混凝土，以考量箍筋與鋼骨對混凝土圍束效應的貢獻；依據所假設之各材料應力-應變關係，可計算構材之彎矩強度與曲率關係。研究結果顯示，分析模式能準確預測實驗結果，驗證箍筋間距較密者具有較佳之圍束能力；T字型鋼骨SRC構材受撓曲作用時，鋼骨偏向拉力側則擁有較高之極限彎矩強度，但構材之韌性表現則較鋼骨偏向壓力側差；SRC構材承受較高軸力作用下，其韌性表現皆不如承受較低軸力作用的試體。此外，分析模式較ACI-318與AISC-LRFD規範更能準確預測SRC構材之極限彎矩強度。

This study aims to examine the behavior of steel reinforced concrete (SRC) beam-column members under loading status either pure bending moment or axial force-bending moment. Numerically parametric examinations were conducted to investigate the confined effects of the concrete on the ultimate strength and ductility of the SRC members. In the analytical model, three different confined zones of the concrete in the SRC section, including the unconfined concrete, the partially confined concrete, and the highly confined concrete, were defined for considering the confining effects contributed from the lateral reinforcement as well as the structural steel shape. By assuming the stress-strain relationship of each material, the relations of flexural strength and curvature of the SRC members can be determined. The numerical model can predict well the experimental results. The SRC members with closer lateral tie spacing lead to better post-failure behavior. Members with T-shaped structural steel in the tension side of the bending moment have higher ultimate strength but worse ductility than those with steel in the compression side. The SRC beam-column members subjected to high axial force have worse post-failure behavior than those under low axial force. Furthermore, the numerical model can accurately predict the ultimate flexural strength than ACI 318 building code and the AISC-LRFD specification.