The Static And Dynamic Mechanical Properties Of Concrete After High Temperature

As a engineering material, concrete is widely used on the construction works who are possible to expose to the high temperature and impact load. If you don’t know the mechanical property of concrete in such conditions, you can’t make the structural design safely. So it is necessary to study the mechanical properties of concrete with complex conditions.In this paper, the research is based on a kind of ordinary concrete which the strength grade is C35, and there are two ways to do the study including making mechanical tests and establishing the constitutive model. For the tests, putting the concrete specimens under high temperature and cooling down by who modes. Then discussing the mechanical law of compressive strength, elastic modulus and tensile strength under static force, and mechanical law of compressive strength under dynamic force. For the constitutive model, based on the non-linear elastic constitutive equation, considering the damage factor and the strain rate, establishing a proper constitutive equation. The details and main conclusions are as follows:The mechanics performance of concrete is related to the temperature and cooling mode. With the temperature increasing, the elastic modulus and compressive under static force decreasing, but the strain corresponding with the peek stress increasing. Compared with the natural cooling specimens, the mechanical properties of water cooling specimens are higher when the temperature is below 300 degree, above this temperature, the properties will be weakened. Similarly, the tensile strength is decreasing as the temperature increases.In the dynamic test, the SHPB method is used. The results shows that, the strain rate significantly enhance the compressive strength, but when the temperature is high enough, the enhancement become slighter. While considering all the three factors, there is no obvious changing rules in the strain corresponding with the peek stress.The non-linear elastic constitutive equation established in this paper is compared with the test results, it is proved that, the theoretical arithmetic stress-strain curve is greatly consist with the experiment curve.