高強度鋼骨鋼筋混凝土樑柱行為研究

Abstract

本研究在於探討高強度鋼骨鋼筋混凝土樑柱之極限強度與行為. 首 先對高強度混凝土之力學行為研究, 對以往各種應力-應變取線數值模式 相互比較, 得知各模式對應力-應變曲線上升段之模擬差異甚小, 但由於 對混凝土圍束效應之考量不同, 下降段則有非常明顯的差異, 針對其差異 性建立一應力-應變曲線數值模式. 建立高強度混凝土材料行 為力學分析模式後, 以數值分析方法探討高強度混凝土與鋼骨的合成行 為, 配合非線性有限元素分析程式, 模擬高強度鋼骨鋼筋混凝土樑柱. 由 數值分析所得之軸力-彎矩交互曲線得知, 除於純彎矩狀態下, 規範一般 皆保守的預測設計強度. 根據美國 ACI 規範彎矩放大法之原理, 利用 彎矩放大之方法預測細長柱軸向強度, 與數值分析所得之結果極為吻合. 使用高強度混凝土可提高鋼骨鋼筋混凝土樑柱之極限強度甚大, 但鋼骨鋼 筋混凝土樑柱的行為受混凝土的行為影響甚大, 其整體行為之韌性仍有待 改善; 對於採用更高強度鋼骨之鋼骨鋼筋混凝土樑柱, 將僅提高柱的極限 強度, 但對於其力學行為特性之影響改變甚小. The use of the high strength concrete with a compressive strength of equalto or more than 8000 psi has increased significantly. This research conductsthe analytical studies to investigate the behavior and ultimate strength of highstrength steel reinforced concrete(SRC)beam-columns. Previous analytical models of stress-strain curves for the high strength concrete are studies and compared each other. The models show that the ascending parts of the stress-strain curves are close each other while the descending parts are away due to the difference of the consideration for the confinement.A model is proposed which is adjusted from the previous models to consider thecharacteristics of the confined high strength concrete. A uniaxial finite element inelastic analysis is performed. The behavior of the high strength SRC beam-columns is simulated and predicted by the analyticalwork. A comparison of analytical result and design strength is made. It is found from the P-M diagram that the AISC-LRFD specification is conservative except the pure bending state. Using current ACI momentmagnified method canpredict the analytical result well. The high strength SRCbeam-columns demonstrate higher ultimate strength, however the post-buckling behavior is in a brittle mode which related to the mechanical behavior of the high strength concrete.