考虑低周疲劳效应的圆管截面钢支撑现象滞回模型

通过ABAQUS分析软件对一系列不同长细比、径厚比圆管截面钢支撑的压屈承载力、非线性屈曲平衡路径、卸载 再加载路径及损伤进行计算和统计，并选取典型构件计算结果与现有试验结果进行了对比，证明了有限元模型的准确性。通过统计的数值数据及现有的试验数据，拟合了简单、有效的圆管截面钢支撑现象滞回模型。该模型采用Coffin-Manson公式和Miner线性累积法则进行支撑低周疲劳损伤预测，建立了材料强度折减与疲劳损伤的相关公式，可以考虑支撑在滞回过程中的一些复杂非线性行为，如受拉屈服、受压非线性屈曲、包辛格效应及低周疲劳效应引起的材料强度折减和断裂等。该模型预测的支撑滞回曲线和累积能量耗散曲线与现有试验和校正的有限元模型的计算结果吻合较好，且计算耗时大幅缩减，适用于圆管截面钢支撑结构的非线性分析。

Phenomenological hysteretic model considering low-cyclefatigue effects for hollow circular steel braces

ABAQUS was used to calculate the buckling capacity, equilibrium path of nonlinear buckling, unloading-reloading paths and damages of a series of hollow circular steel braces with varying slenderness and width-to-thickness ratios. The simulation results of a typical brace were compared with experiments to verify the accuracy of the finite element model. A simple yet efficient phenomenological hysteretic model was calibrated on the basis of the available experimental results and based on a series of numerical simulations by ABAQUS. The Coffin Manson equation coupled with Miner linear damage theory was adopted to predict the low cycle fatigure effects. The equation of the cumulative yielding strength degradation was also formulated with the cumulative fatigue damage. Therefore, this proposed model can account for several nonlinear hysteretic behavior, such as yielding in tension, nonlinear buckling in compression, Bauschinger effect, strength degradation and fracture due to low-cycle fatigue. The hysteretic loops and cumulative energy dissipation predicted by the model are consistent with the previous tests and finite element simulation results.In addition,the model requires much less computing time and is therefore suitable for nonlinear analysis of hollow circular steel brace structures.