基于Kelvin链率型模型的混凝土徐变有限元计算

基于混凝土徐变固结理论,推导出一种计算混凝土徐变的递推格式,递推过程可以结合使用有限元商用软件来完成.首先,基于Kelvin链模型,将徐变Volterra积分方程转化为率型徐变积分微分方程;其次,将时间进行离散,通过引入中间变量,把率型徐变积分微分方程转化为可递推计算徐变方程;再次,使用可递推计算徐变方程,结合应力应变...

Finite Element Calculation of Concrete Creep Based on Rate -Type Law Visualized by the Kelvin Chain Model

Based on the solidification theory, an recursion format for calculating concrete creep is derived. The recursion process can be programmed by commercial finite element software. Firstly, the creep Volterra integral equation was transformed into a rate-type creep integrodifferential equation based on the Kelvin chain model; secondly, the integrodifferential equation was transformed into a recursive creep calculation equation by discretizing the time and introducing intermediate variables; thirdly, a stress-strain incremental elastic constitutive relationship with initial strain was established by using the recursive calculation. The stress-strain incremental elastic constitutive relationship was suitable for complex stress conditions. Finally, as an application, the Ansys finite element commercial software was re-developed by modifying the material constitutive subroutine Usermat with Fortran language. Some existing examples were calculated by the program. The calculation results show that proposed method has satisfactory accuracy by comparing with the existing results. The proposed method does not need to store the stress history, which greatly improves the calculation efficiency, and also provides another effective way for the creep calculation of complex concrete structure.