Finite Element Analysis On Thermal Stress Of Multi-doped Modified Material Mass Concrete

As the mass appearances of high-rise buildings,large span structures,special structures and large-equipment foundations,mass concrete has been used more and more widely to practical engineering.Because of a larger size of mass concrete cross-section,cement hydration will be released in a large number of hydration heats.However thermal conductivity of concrete is poor and concrete has a larger volume,the cement hydration heat is not easy to disappear,which cause the larger temperature difference between the interior and the surface of concretes,and this creats the temperature stress,which finally causes the appearance of the concretes temperature crack and affects its usability and durability and so on.The traditional large volume concrete control method,mainly based on minimizing the amount of cement as the starting point.But the reduction of cement consumption will significantly reduce the tensile properties of concrete.Cracking from the temperature control point of view,is not necessarily conducive to thermal crack control of super-size concrete.If we can add an appropriate amount of fly ash to make prepared concrete reduce the amount of cement to a certain extent.While the use of modified materials mix concrete,it will have certain "toughness" and form HPC(High performance concrete ) which is adapt to environmental conditions and load requirements.It can solve the thermal cracks of mass concrete effectively.This article conducts mechanical property study on the concretes which add the modified materials such as fly ash,mulsified asphalt,polypropylene fibre and so on.This article uses the large-scale finite element analysis software to carry on the numerical simulation analysis to the engineering case mass concrete.Then we compare the experimental study result with the theoretical analysis result,and confirme the ability to resist temperature stress on the modified material concretes' own.The main work is as follows: 1) According to the heat conduction basic principle and the finite element method,we carry on the theoretical analysis to deformation crack mechanism and thermal stress of the engineering case mass concrete structure.Simultaneously we consider the influence from such factors as shrinkage and creep to the mass concrete deformation cracks;2) We carry on the experiment to mechanics properties of the multi-doped modified material concretes which add the modified materials such as fly ash,mulsified asphalt,polypropylene fibre and so on,including the concrete compressive strength,axial tensile strength and elastic modulus of concrete,etc.We have discussed effects on mechanical properties of concrete with the modified material and obtained the main rule;3) We carry on thermal stress simulation analysis using finite element analysis software MIDAS/gen to the engineering ease.We research on mass concrete temperature and thermal stress distribution,and compare with the concretes with modified material,while demonstration of the feasibility of new Multi-doped High performance concrete in practical engineering applications.