Research On Viscous-elastic Random Algorithms For Concrete Shrinkage And Creep

In practical engineering,concrete will undergo time-varying deformation such as creep and shrinkage under the action of load and environmental factors.In the actual structure,these deformation should be considered to ensure the safety of the structure.At the same time,concrete is a kind of inhomogeneous material.Uncertainty of material properties and environmental effects of concrete will lead to uncertainty of creep and shrinkage deformation of concrete.Based on stochastic finite element method and perturbation theory,the finite element analysis method considering creep shrinkage and uncertainty of concrete is studied in this paper.The main research work is as follows:(1)The uncertainty analysis methods,creep models and creep algorithms of engineering structures are discussed,and their values and shortcomings are analyzed.(2)Basing on the theory of creep and shrinkage of model B3/B4 and the step by step algorithm of creep and shrinkage,the consideration of environmental temperature and humidity in model B3/B4 is rewritten to variable temperature and humidity and introduced into the step-by-step calculation.In this paper,a stochastic finite element formulation of perturbation method is derived by combining step-by-step method with random field theory and perturbation theory.(3)A two-dimensional stochastic finite element program "HORO_EX" for creep and shrinkage perturbation with variable temperature and humidity is developed by using MATLAB.The program is mainly divided into random field processing part and random finite element part.It can deal with random field of material parameters,random surface force and random physical force.Some examples are validated by the finite element program.The results show that the difference between creep analysis with variable temperature and humidity and creep analysis with average temperature and humidity can not be ignored.The difference between creep analysis with random field and without random field is relatively small,but it also can not be ignored.The perturbation stochastic finite element method is a practical method for calculating creep and randomness of concrete,and it does not need to repeat the calculation of response surface or a large number of sampling samples.