高层建筑框架结构梁柱节点疲劳强度预测模型

Prediction Model of Fatigue Strength of Beam Column Joints in High-Rise Building Frame Structure

地震作用下,由于震动幅循环次数少,钢框架梁柱节点容易发生超低周疲劳断裂现象,为此设计高层建筑框架结构梁柱节点疲劳强度预测模型。将名义应力、应变转换为真实值,获得各个部分的本构关系。在此基础上合理运算出钢管环向指数和梁柱节点强度,获得超高强度梁柱节点的本构关系。再根据改进的延性破坏准则构建出低周疲劳寿命拟合曲线,运用该曲线得到梁柱节点的屈服曲率与位移程度。并根据位移延性合理运算获取梁柱外钢管混凝土柱的最大荷载强度,最终组建BP网络模型完成对梁柱节点疲劳强度的预测。实验结果表明:所提方法预测准确性与稳定性较高,说明该方法具有高效性和广泛适用性。

Due to the low number of vibration amplitude cycles under the action of earthquake, the ultra-low cycle fatigue fracture happens easily in steel frame beam-column joints. Therefore, a model to predict fatigue strength of beam-column joints in high-rise building frame was designed. The nominal stress and strain were converted into the real values, so as to obtain the constitutive relation of each part. On this basis, the circumferential index of steel pipe and the strength of beam-column joints were reasonably calculated to obtain the constitutive relationship between ultra-high-strength beam-column joints. Based on the improved ductility failure criterion, a fitting curve of low-cycle fatigue lifetime was constructed, and then the yield curvature and displacement of beam-column joint were obtained by this curve. Moreover, the maximum load strength of the concrete filled steel tube outside the beam-column was obtained by reasonable calculation of displacement ductility. Finally, BP network model was built to predict the fatigue strength of beam-column joint. Simulation results show that the proposed method has high prediction accuracy and stability. This method is efficient and widely applicable.