本研究旨在探討高性能混凝土梁受到扭矩與剪力組合載重作用下之強度與變形行為，另由構件內、外部應變之變化，探討因組合載重比例變化對於試體破壞模式改變之影響。

　　試體部分共規劃六根實心斷面與七根空心斷面之高性能鋼筋混凝土試體，試體斷面尺寸為350×500 mm，保護層為25 mm。混凝土之抗壓強度為58～68 MPa。試體之全長分別為3100 mm與4400 mm，中央測試區之長度分別為1600 mm與1500 mm。主要討論之變數為扭矩與剪力比例值(T/V)及實心斷面與空心斷面。

　　試驗結果顯示：（1）隨著試體所受到T/V比值的降低，試體表面開裂型式會由近似立體桁架型式（TypeⅠ）轉變為類斜彎矩型式（TypeⅡ），進而再轉變為近似平面桁架型式（TypeⅢ），當試體加載超過極限強度後，實心斷面試體之強度遞減會較空心斷面試體慢。（2）試體表面混凝土翹曲現象會隨著T/V比值的下降而減弱，且因扭矩與剪力組合載重作用造成不同受力面上變形的差異會產生側向彎曲，側向曲率會隨著T/V比值的下降先增加然後減少，其中以開裂型式為TYPE Ⅱ試體之側向曲率最大，且空心斷面試體之側向彎曲現象會較實心斷面試體顯著。（3）試體正面混凝土在45∘方向上受壓力區域會隨著T/V比值的降低而增加，而試體背面混凝土在45∘方向上受壓力區域會隨著T/V比值的降低而減小。（4）在受到扭矩與剪力組合載重作用下，配置低鋼筋量之高性能混凝土實心斷面試體會有剪力鬆弛的現象，但空心斷面試體因受到壁厚之限制，並無剪力鬆弛的現象。（5）TypeⅠ開裂型式之試體，不論實心或空心斷面，梁試體正面之平均主張與平均主壓應變，皆相當接近由軟化桁架模式所計算出之理論值。同時，由實驗結果顯示混凝土斜壓桿件之擠碎現象為TypeⅠ開裂型式試體破壞主因。（6）TypeⅡ開裂型式空心斷面試體之破壞主因為背面產生混凝土擠碎現象。

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