考虑损伤累积的圆钢管本构模型力学行为特点与数值分析

Mechanical Performance Characteristics and Numerical Analysis of Consititutive Model for Circular Steel Pipes Considering Damage Accumulation

由于单层网壳结构主要以圆钢管为主,因此圆钢管本构模型更适用于研究单层网壳结构的力学行为。为探究材料损伤累积对单层网壳结构动力响应的影响,本文以圆钢管考虑损伤累积的本构模型为研究对象,通过与Prandtl–Reuss材料本构模型在屈服准则、弹性刚度矩阵、弹塑性刚度矩阵、加载准则、流动法则及应力跌落等方面的对比,分析其力学行为特点,给出其数值积分格式,并基于有限元软件ANSYS开发了考虑损伤累积的用户材料子程序,采用该子程序研究单层网壳在强震作用下的动力响应。结果表明:Prandtl–Reuss材料模型高估了单层网壳结构的抗震性能,考虑材料损伤累积的结构失效时,结构动力极限荷载相比于P–R模型降低了12.24%,绝大多数杆件全截面屈服,形成大量塑性区带。一方面,损伤累积效应会降低结构的动力极限荷载,扩大损伤分布,加深损伤程度,加速结构破坏进程;另一方面,也将造成结构的失效模式由动力失稳向强度破坏转变。本文基于有限元软件ANSYS开发的考虑圆钢管损伤累积的材料子程序具有较高的计算精度,且其数值积分策略及用户材料子程序有效、可行,能够为单层网壳结构的抗震性能提供更加精确的分析与工程设计。

Since the single-layer reticulated shell structure is mainly composed of circular steel tubes,the constitutive model for circular steel tube is more suitable to study the mechanical behavior of single-layer reticulated shell structures.In this study,the constitutive model of circular steel pipe considering damage accumulation was analyzed with yield criteria,elastic stiffness matrix,elastic-plastic stiffness matrix,loading criterion,flow rule,and stress-drop,and it was compared to the constitutive model of Prandtl-Reuss material to explore the mechanical performance.By providing the format of the numerical integration,this study also explored the influence of material damage accumulation on the dynamic re-sponse of single-layer reticulated shell structure.Besides,a user-defined material subroutine considering damage accumulation was incorporated into ANSYS to investigate the dynamic response of single-layer latticed shell under earthquake action.The results show that seismic performance of single-layer reticulated shell was overestimated in Prandtl-Reuss material model.The dynamic ultimate load of structure was reduced by 12.24%compared with the Prandtl–Reuss model,and most of the members yield in the whole section,forming a large number of plastic zones,when considering the structural failure of material damage accumulation.On the other hand,the cumulative damage had the influence on redu-cing the dynamic limit load of the structure,expanding the damage distribution,deepening the damage degree and accelerating the process of structural failure,which also caused the failure mode of the structure to change from dynamic instability to strength failure.Moreover,the numer-ical integration scheme was proposed in this study showing better rationality and efficiency,and the calculation accuracy of the user-defined ma-terial subroutine is reliable to provide more accurate analysis and engineering design for the seismic performance of single-layer reticulated shell structures.