Experimental Study On Mechanics Properties Of Concrete After High Temperature

Concrete is a kind of multiphase mixture material and its mechanical properties can be effected by many factors, which make the behavior of concrete after high temperature more complex than one at room temperature. When the mechanical propertis of concrete after high temperature is studied, temperature is the most considered factor; the cooling-method and other factors are usually ignored. It is very important in analyzing the relationship between properties and temperature and other factors of concrete to get the residual strength of concrete after fire. It may provide basis for the Restoration and reinforcement of fired structures. The mechanical properties of concrete material after high-temperature and differente size of spice& cooling-method as well as the bonding strength between steel bar and concrete after high temperature are tested and analyzed. The main work of this paper are summarized as follows:(1) Experimental researches were made on the variation of concrete mechanical behavior with different temperature and size of specimen, and the formula which shows the relationship between compressive strength and temperature varying is established; experimental research on the correlation of elastic modulus and temperature is carried out, the formula between elastic attenuation parameters and temperature is established by regression analysis.(2) Experimental researches were made on strength and deformation of concrete with different cooling method, the internal causes and regulations of mechanical changes of concrete cooled by wartering are analyzed; the formula between compression and cooling method after high temperature are established.(3) Experimental researches were made on split-strength of concrete and the bonding-slip strength between concrete and steel bar after high temperature; the formula which shows the relationship between splitting strength and temperature is established, the relationship between stress-slip curves and temperature are analyzed; relationship between split-strength and ultimate bonding strength is analyzed, the formula between them after different temperature is established by regression analysis.