考虑地震应变率效应的木材三维弹塑性损伤本构模型及其数值实现

Elastic-plastic damage constitutive model and numerical implementation for timber considering seismic strain rate effects

木结构在服役过程中可能遭遇地震作用,木材表现出明显的地震应变率敏感性,需要建立考虑地震应变率效应的木材非线性本构模型。文章系统梳理已有研究中木材在不同地震应变率水平、不同纹理方向的试验结果,分析其不同纹理方向考虑应变率影响的强度与弹性模量绝对值统计规律性,建立木材考虑地震应变率效应的强度与弹性模量地震应变率影响系数表征模型。在此基础上,基于连续介质损伤力学建立考虑地震应变率效应的木材三维弹塑性损伤本构模型,编写相应的UMAT子程序,并将其嵌入ABAQUS有限元软件中。采用所建立的弹塑性损伤本构模型对木材进行顺纹与横纹受压加载模拟,模型结果与试验结果吻合较好,验证了所建本构模型及UMAT子程序的正确性。研究成果可为木结构的抗震分析与评估提供更符合实际的本构模型支持。

Earthquakes may occur during the service of timber structures,and timber exhibits evident seismic strain rate sensitivity.Therefore,it is necessary to establish a nonlinear constitutive model of timber considering the seismic strain rate effect.The test results of timber were systematically sorted out under different seismic strain rate levels and different grain orientations,the statistical rules of the absolute values of strength and elastic modulus of timber under different strain rates in different grain directions were analyzed,and the seismic strain rate impact factor model of strength and elastic modulus of timber considering the effect of seismic strain rates was established.Based on the continuum damage mechanics,a three-dimensional elastic-plastic damage constitutive model of timber considering seismic strain rate effect was established,and the corresponding UMAT subroutine was coded and incorporated into ABAQUS software.Furthermore,the elastic-plastic damage constitutive model was used to simulate the compressive loading parallel or perpendicular-to-grain of timber.Numerical results agreed well with the measured results,validating the correctness of the constitutive model and the UMAT subroutine.The proposed constitutive model can provide model support for the seismic analysis and evaluation of timber structures.