Six specimens of abnormal interior joints were tested under reversed cyclic loading. Experimental studies were carried out to investigate the influence of joint core dimension and axial compression ratio on the crack resistance performance of irregular joints. Test results indicated that cracks mainly appeared in the minor core ( determined by the low beam and the top column) . The cracking load was about 50% ~ 60% of the ultimate load of irregular joints, and the crack resistance was worse than that of ordinary joints. The crack shear strength was primarily resisted by the minor core concrete, and the axial compression ratio was a significant parameter for increasing the crack resistance capacity. The column axial load fluctuated from time to time because the unbalanced force occurred in the beam column subassembly, due to significant difference on stiffness between the high beam and the low beam. Based on the test results, a theoretical expression was proposed for the axial load influence factors a. A theoretical formula of crack resistance capacity was proposed. The formula was verified by using 19 experimental test data of 12 irregular joints.%通过6个钢筋混凝土框架异型中节点试件在低周反复荷载作用下的试验研究,分析了节点核心区尺寸、轴压比等因素对异型节点抗裂性能的影响.研究表明,异型节点初裂时斜裂缝主要出现在由小梁和上柱构成的小核心区,核心区开裂荷载约为50%～60%极限荷载,抗裂性能较常规节点劣化,初裂阶段的剪力基本由小核心区混凝土承担,合理增大轴压比可以提高异型节点的抗裂承载能力.异型中节点由于大小梁刚度不同,反复荷载下柱端轴压力会发生波动.通过理论分析推导出柱端轴压力影响系数α的计算表达式,在此基础上提出包含系数α的异型中节点抗裂承载力计算公式,并通过国内外12个异型节点试件的19组试验数据对其进行验证,吻合良好.
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