Study On The Nonlinear Thermal Contact Resistance Model Of Concrete Filled Steel Tube Column Under Fire Condition

Nowadays,with the widespread use of the concrete filled steel tube column in the engineering,as well as huge losses and hazards caused by fire in high-rise and super high-rise buildings,the temperature and displacement response of high-rise building under the action of the fire has received more and more attention.Concrete-filled steel tube column due to the contact between steel tube and concrete is not tight,under the effect of fire will produce the thermal contact resistance,the existence of the thermal contact resistance will affect the temperature and displacement response of the concrete filled steel tubular column under the fire.So researching the nonlinear factors influence the thermal contact resistance of concrete filled steel tube column,establishing the nonlinear thermal contact resistance model,for the study the accurate temperature response and the displacement response of concrete filled steel tube columns under the action of high temperature fire has an important significance.This article will from the following several aspects to study the nonlinear model of the thermal contact resistance of concrete filled steel tube column:(1)Considering many factors such as the initial clearance,interface temperature,the blackness of the steel and the concrete affecting the thermal contact resistance,establishing the nonlinear theory model of thermal contact resistance of concrete filled steel tube column model by the basic theory of heat conduction,and through the actual temperature load curve of concrete filled steel tube column measured in experiment verification,the real rationality of this theory was verified.(2)Choose the appropriate finite element model,determine the material's thermal parameters and boundary conditions after introducing the contact thermal resistance of nonlinear model of concrete filled steel tube column of concrete filled steel tubular column under the action of the fire temperature,thermal analysis for concrete filled steel tubular column temperature field distribution,Compared with the actual temperature of concrete filled steel tube column load to test verification,got the fire under the action of high temperature precise temperature field distribution of concrete filled steel tube column.(3)On the basis of thermal analysis,the reasonable choice of steel,concreteconstitutive model,the thermal-mechanical coupling analysis carried out,get the stress and strain response of concrete filled steel tube column under the action of high temperature.