Study on Collapse Limit of Reinforced Concrete Buildings

通过试验验证了2001年颁布的《既有钢筋混凝土建筑抗震鉴定标准》中推荐的剩余轴向承载能力。对强度相对较低的柱状试件进行了试验。试件设计为三种典型的破坏模式，即极脆剪切破坏、剪切破坏和弯曲破坏。在恒定轴压比、恒剪配筋率p_w和恒定主筋的情况下，仅改变柱高即可控制破坏模式。在侧向荷载反转后，通过轴向加载研究了残余轴压承载力，在极脆性破坏柱中，在0.2≦p_w≦0.4范围内，残余轴压承载力超过了标准的推荐值。在受剪破坏柱中，在延性指数为1.27和2.32时，在0.2≦p_w≦0.4时，剩余轴向承载能力的试验结果超过了标准的推荐值。在受弯破坏柱中，在延性指数为2.0时，在0.2≦p_w≦0.4时，剩余轴向承载能力的试验结果明显超过标准中的推荐值。然而，在延性指数为3.0时，试验结果与推荐值基本相同。《既有钢筋混凝土建筑抗震鉴定标准》中建议的剩余轴向承载能力，即使在低强度混凝土范围内，也被验证为近似合适的假定，与破坏模式无关。

Residual axial load capacity, recommended in the Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings published in 2001,was verified by experiment. Column specimens with relatively low strength were tested. The specimens were designed to fail in three typical failure modes, that is, extremely brittle shear failure, shear failure and flexural failure. The failure modes were controlled by only changing the column height, under constant axial load ratio, constant shear reinforcement ratio p_w, and constant main rebar. After the lateral load reversals, the residual axial capacity was investigated by loading in the axial direction.In the extremely brittle failure columns, the residual axial load capacity exceeded that recommended in the standard in the range of 0.2≦p_w≦O.4. In the shear failure columns, in the range of 0.2≦p_w≦0.4,test results of residual axial load capacity exceeded that recommended in the standard at 1.27 and 2.32 of ductility index. In the flexural failure columns, in the range of 0.2≦p_w≦0.4, test results of residual axial load capacity exceeded significantly that recommended in the standard at 2.0 of ductility index. However, at 3.0 of ductility index, the test result was almost equal to the recommended value. The residual axial load capacity, recommended in the Standard for Seismic Evaluation of Existing Reinforced Concrete Buildings, was verified to be approximately appropriate assumption even in the range of low strength concrete, independent of failure modes.