基于刚度损伤并考虑强度退化的钢筋模型

Hysteretic constitutive model of reinforcement based on stiffness damage and considering strength degradation

Clough本构广泛应用于现浇节点的滞回模拟中,针对原始Clough本构中的应力可能会超出材料自身极限强度的问题,提出了一种根据节点刚度损伤来推导钢筋本构的算法。该算法依次建立现浇节点刚度退化与构件中钢筋模量退化间的关系及梁端位移角与钢筋应变的关系,根据以上关系建立钢筋强度退化的表达式,并得到钢筋的本构模型。使用Fortran语言编写自定义纤维单元材料子程序,利用有限元软件ABAQUS进行两个算例验证,得到的模拟滞回曲线具有捏缩现象,形状与试验吻合良好,耗能和延性等方面可与试验接近,在峰值点位移角的预测方面也具备一定的优势,同时,本构在二维和三维模型中均有良好的收敛性,且精度较高,可以应用于实际工程中。

The Clough model is widely used in the hysteretic simulation of hysteretic cast-in-situ joints.Aiming at the problem that the stress in the original Clough model may exceed the material’s ultimate strength,this paper proposes an algorithm based on the stiffness damage of joints to derive the constitutive model of reinforcement.The algorithm successively establishes the relationship between the stiffness degradation of cast-in-situ joints and the degradation of reinforcement modulus,and the relationships between beam end displacement angle and reinforcement strain.According to the above relationship,the expression of reinforcement strength degradation is established,and the constitutive reinforcement model is obtained.Then,the UMAT subroutine of fiber element is written in Fortran language,and two examples are verified by using the finite element software ABAQUS.The simulated hysteretic curve has the pinch phenomenon;the shape of the curve is in good agreement with the test;the energy consumption and ductility can be close to the test,and it has certain advantages in predicting peak displacement angle.Meanwhile,the constitutive model has good convergence and high precision in two and three-dimensional models,which can be applied to practical engineering.