Numerical Simulation Of High Strength Concrete Creep Process Under Different Stress Levels In Meso Scale

The concrete creep model which based on the theory of porous media are supposed to compile the creep analysis program for the purpose of exploring influence for concrete creep under different stress levels.Based on the experiment result under uniaxial compressive load,cyclic load and biaxial prestressing,besides,depending on the thickness of the aggregate,cement,water evaporation can be composed of a three-phase composite,The program calculated the creep coefficient and creep displacement under three stress state,Meanwhile the program simulated the interaction between aggregate,mortar and water inside the concrete.Above all,the contact of meso creep mechanism and macro creep phenomena is established under considering the effect of different stress states,water,aggregate and mortar factors.Through simulation,Under uniaxial tensile stress,It studied the relation between the concrete creep and aggregate content,aggregate intensity,mortar moisture.Besides,Through establishing the relation between the liquid flowing rate and the pore pressure,the reason that concrete creep under tensile stress is smaller than that under compressive stress is given.Under cyclic load,It studied the relation between the mean stress,stress amplitude between creep coefficient,Besides,through establishing the relation between the distribution of liquid flowing rate,the distribution of pore pressure and the equivalent stress,the reason that concrete creep under cycle stress is bigger than that under compressive stress is given.Under biaxial stress,It studied the relation between vertical stress,transverse stress and creep coefficient,what’s more,the reason that concrete creep under biaxial stress is smaller than that under compressive stress is given.Research results confirms that:Firstly,theory and procedures used in this paper are reliable,numerical simulation method can describe the movement of aggregate,montar and water inside the concrete at the mesoscopic scale.Secondly,Compared with the uniaxial compressive stress,uniaxial tensile stress decreases creep,uniaxial compressive stress will increase the cycle creep and biaxial stress will decreases creep,three patterns of stress state through affecting the movement of water speeds up or slow down the redistribution of internal forces between aggregate and cement mortar,thus influences the concrete creep.Thirdly,considering the effects of three levels of stress creep,creep correction factor is obtained combining with engineering practice.Finally the structure who is sensitive to creep should be reduce biaxial prestress lose and avoid reciprocating action to reduce creep.The innovation of this paper reflected in four points,first of all,The concrete creep model which based on the theory of porous media and mixture theory are supposed to compile the creep analysis program which considered different stress levels.secondly,through comparing the results between experimental and simulation,it studied the relation between different stress levels and concrete creep.Thirdly,it proposed the mechanism of concrete creep innovatively through researching the discipline of concrete creep movement at macro-meso.Finally,the creep correction coefficient considered three kinds of stress level is given which combined with engineering practice.