基于ANSYS二次开发的早龄期混凝土徐变应力计算

Calculation of Creep Stress of Early-age Concrete Based on Further Development of ANSYS

徐变是混凝土材料所具有的时变特性,对早龄期混凝土的应力影响很大,不可忽略,然而工程界主流的通用有限元程序不支持混凝土徐变的计算,不利于工程应用。为此,笔者通过对ANSYS用户子程序usermat进行二次开发,编写了自定义的材料模型,利用ANSYS程序实现了混凝土弹性徐变方程的隐式解法。在此基础上,通过算例验证了该二次开发子程序的正确性,并将其应用于实际工程,通过对比,采用弹性徐变方程隐式解法求得的计算结果与实测值的变化规律相同,数据也比较吻合,误差范围一般在0.3 MPa以内,证明该子程序具有较好的精度,可以推广应用于工程早龄期混凝土温度徐变应力的预测和计算。

As a time-dependent property of concrete material,creep imposes significant influence on the stress ofearly-age concrete. However,it is difficult in engineering to calculate the creep stress by using common available finite element programs. In view of this,through further development of the ANSYS user subroutine usermat,a user-defined material model was developed to introduce the implicit solution to the concrete creep equation. With the largest error lower than 0. 3 MPa,the user subroutine usermat was verified through calculation examples and was applied to engineering. The results of the implicit concrete creep equation are in good agreement with measured values,and their variation trends are the same. The user subroutine usermat can be applied to engineering to predict and calculate the thermal creep stress of early- age concrete.