Research On Thermal Radiation Characteristics Of Concrete Filled Steel Tubular Column Surfaces And Thermal Response Behavior Under Fire

Concrete-filled steel tube structure is a new structure between steel structure and reinforced concrete structure.With the rapid development of concrete-filled steel tubular components in bridges and buildings,fire resistance is always a hidden danger.Due to its extensive use in super high-rise buildings,it is particularly important to study the thermal response of concrete-filled steel tubular columns under fire.Because incomplete contact of the contact surface of the concrete filled steel tube column will cause contact thermal resistance,which will affect its thermal response behavior.In recent years,many scholars have mathematically modeled the contact thermal resistance of the contact surface of concrete-filled steel tubular columns.It is shown that one of the important factors affecting the contact thermal resistance is the thermal emissivity of the material.The thermal response behavior of columns under high temperature is studied,so it is necessary to study the thermal radiation characteristics of concrete filled steel tube columns under fire and high temperature environment.This article focuses on the thermal radiation characteristics of concrete-filled steel tubular columns under fire and high temperature environments.It mainly includes the determination of the thermal emissivity of the material surface and the analysis of the thermal response behavior of components under fire.The specific research contents include the following aspects:(1)Based on the theoretical knowledge of heat transfer,theoretical analysis of the influencing factors of the thermal response behavior of concrete-filled steel tubular columns under high temperature environment of fire,and theoretically deduced that the temperature dependence of the thermal emissivity of steel and concrete are related to the fire Importance in Thermal Response Behavior of Concrete Filled Steel Tubular Columns.(2)Infrared thermal imaging cameras are used to test several typical test pieces of steel pipes and concrete columns under high-temperature fire conditions.The surface emissivity of materials at different temperatures is tested,and the obtained data is analyzed and processed using software.Fitting relationship between temperature and thermal emissivity of typical test pieces.(3)Several key issues in modeling the thermal response behavior of concrete-filled steel tubular columns under fire are proposed,and the modeling is completed,a nonlinear thermal contact resistance model is introduced,and the typical test piece temperature of concrete-filled steel tubular columns under high temperature under fire-The thermalradiation fitting relationship is used to numerically simulate the thermal response behavior of concrete filled steel tube columns under fire,and the corresponding temperature field distribution is obtained.This paper analyzes the influence of surface thermal emissivity,flame temperature and flame blackness of concrete-filled steel tubular columns on the thermal response behavior of concrete-filled steel tubular columns under fire.(4)The results show that the thermal emissivity of the surface of the concrete-filled steel tube column has a significant effect on the thermal response behavior under fire.The smaller the surface thermal emissivity,the better the fire resistance of the structure;the flame temperature is also an important factor affecting the fire performance.Indexes,the thermal response characteristics of components under different temperature flames are different;the flame blackness in the range of 0.7 to 0.9 does not have much influence on the overall thermal response behavior of concrete filled steel tube columns under fire.