Compressive Strength Test And Numerical Simulation Of Desert Sand Concrete After High Temperature

At present,building fire has become the most serious disaster,causing the most serious damage.Therefore,the study of mechanical properties of concrete after high temperature has very important significance.Sand is one of the indispensable materials for the preparation of concrete.In order to protect the ecological environment,many places have begun to limit or ban river sand.In the western part of China,desert sand reserves are abundant and concentrated.Applying desert sand to concrete can not only solve the problem of the shortage of medium sand,but also alleviate the pressure of desertification.In this paper,the compressive strength of desert sand concrete after high temperature is studied experimentally.The influence of temperature and desert sand replacement rate on the compressive strength of desert sand concrete after high temperature is analyzed.The mechanical properties of desert sand mortar after high temperature are tested.The effects of temperature and desert sand replacement rate on the peak stress,peak strain,elastic modulus,Poisson's ratio and stress-strain relationship of desert sand mortar after high temperature were analyzed.The desert sand concrete is regarded as a two-phase composite material composed of desert sand mortar and coarse aggregate.The parameters of the constitutive model of the desert sand mortar after high temperature are determined by experiments.The numerical simulation of the uniaxial compression failure of the desert sand concrete after high temperature is carried out by ANSYS.The effects of specimen size,coarse aggregate volume,coarse aggregate minimum particle size,coarse aggregate intermediate particle size and coarse aggregate maximum particle size on the compressive strength of desert sand concrete after high temperature were analyzed.The main contents are as follows:1)The compressive strength test of desert sand concrete after high temperature was carried out to analyze the influence of temperature and desert sand replacement rate on compressive strength.The test results show that with the increase of temperature,the compressive strength increased first and then decreases.With the increase of desert sand replacement rate,the compressive strength increased first and then decreased.2)The mechanical properties of desert sand mortar were studied after high temperature.The effects of temperature and desert sand replacement rate on peak stress,elastic modulus,peak strain,Poisson's ratio and stress-strain curve were analyzed.The test results showed that the compressive strength and elastic modulus initially decreased,then increased and finially decreased with the increase of temperature,and the Poisson's ratio and peak strain decrease first and then increase.With the increase of desert sand replacement rate,the compressive strength and elastic modulus of desert sand mortar first increased and then decreased.The regression relationship between temperature and desert replacement rate and peak stress,elastic modulus,peak strain and Poisson's ratio was established by regression analysis.The regression relationship between temperature and desert replacement rate and peak stress,elastic modulus,peak strain and Poisson's ratio was established by regression analysis.The uniaxial compression constitutive equation of desert sand mortar after high temperature is given,which provides parameters for the next numerical simulation.3)Numerical simulation of the uniaxial compressive failure process of desert sand concrete after high temperature.The influences of specimen size,coarse aggregate volume content,minimum particle size of coarse aggregate,maximum particle size of coarse aggregate and intermediate particle size of coarse aggregate on the compressive strength of desert sand concrete after high temperature were analyzed.Numerical simulation results showed that the compressive strength of desert sand concrete after high temperature had obvious size effect.The compressive strength of desert sand concrete after high temperature increased firstly,and then decreased with the volume content of coarse aggregate.With the increase of the minimum particle size of coarse aggregate,the compressive strength decreased gradually.With the increase of the intermediate particle size of coarse aggregate,the compressive strength increased first and then decreased.With the increase of the maximum particle size of coarse aggregate,the compressive strength decreased.