外露式钢柱脚恢复力特性分析

HYSTERETIC RESISTANCE MECHANISM OF EXPOSED STEEL COLUMN BASES

  • 摘要: 该文在外露式柱脚拟静力试验的基础上总结了柱脚在压弯和拉弯状态下的受力机理,提出了两种受力状态下柱脚的屈服承载力、极限承载力及转动刚度的计算公式。该文提出的承载力及转动刚度计算结果与试验结果的误差在10%左右,具有较高的计算精度。在试验研究的基础上还提出了两种状态下柱脚的恢复力模型:在压弯状态下,柱脚的滞回曲线呈"旗帜型",骨架曲线由不考虑强度退化的双折线模拟;在拉弯状态下,柱脚的承载力大幅度下降,滞回曲线为饱满曲线,骨架曲线为不考虑锚栓屈服后强度增加的理想弹塑性模型。恢复力模型与试验曲线吻合较好,可有效地反映出不同受力状态及不同锚栓布置下的外露式柱脚的弯矩转角行为,可有效用于分析整体框架的抗震性能。

     

    Abstract: Based on quasi-static test results of exposed columns, the lateral resistance mechanisms of the exposed columns under compressive or tensile axial loads are summarized. The method for predicting the yield moment, ultimate moment, and initial stiffness of exposed column bases under compressive or tensile axial loads is proposed; and the errors of the resulting predictions are within 10% of the experimental tests. A hysteretic model of exposed columns under compressive or tensile axial loads is proposed. Under compressive axial loads, the hysteresis curves of exposed column bases are "flag-shaped", and the backbone curve is simulated using a bilinear model without strain hardening. Under tensile axial loads, the resistance of exposed columns is reduced significantly, and the hysteresis is full. The backbone curve is simulated by an idealized elastic-plastic model which does not consider the strain hardening of the anchor rod. The hysteresis curves from the model agree well with the experimental results. The hysteretic model can represent the bending behavior of exposed column bases with different anchor rod arrangements well, and thus can be used to analyze the seismic performance of whole frames in future research.

     

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