Study on compressive mechanical capabilities of concrete after high temperature exposure and thermo-damage constitutive model

Deterioration of mechanical properties of concrete structure, caused by the high temperature of a fire, would seriously threaten people’s lives and their properties. This paper aims to study the physical and mechanical properties such as strength, deformation, and elastic modulus and the changing regularity of the failure mode of concrete, with the uniaxial compression tests on C35 concrete being separately carried out under normal temperature and high temperature (300–1200 °C). A nonlinear elastic constitutive equation of concrete on thermo-damage is established on the basis of experiment. And its characteristic parameter is identified by the differential coefficient algorithm. Its reliability is testified by comparing and analyzing the calculated curve and testing curve.