Analytical Research On The Influence Of The Thermal Contact Resistance On Fire Resistance Of Concrete Filled Steel Tubular Structure

The concrete filled steel tubular structure is an excellent combined structure, and the CFST structures are widely used in the building world. The thermal contact resistance, between steel and concrete, has a significant impact on the temperature field of the structure. It is very important to study the impact of the thermal contact resistance on the temperature field and fire resistance of the structure. And this will be very important to accurately predict the temperature field, forecast the fire resistance to calculate, and analysis the fire resistance performance optimization.This paper evaluated the influence of the thermal contact resistance on the fire resistance of CFST structures. The main research works are summarized as follows:1) By using the simulation methods to research the influence of the thermal contact resistance on the fire resistance of CFST structures. Calculate the temperature field of CFST columns, and take the comparison of the temperature field between considering the thermal contact resistance and not considering the thermal contact resistance. From the comparison, not considering the thermal contact resistance is not good for calculating of the fire resistance of steel.2) On the basis of the finite element model and experiments, take different values of the thermal contact resistance to calculate the temperature field and compare the results. Then anti-analysis the better values as the temperature. These values are conducive to accurately study the temperature distribution and mechanical performance of CFST structures under fire conditions.3) By adopt the sequentially-coupled thermal-mechanical analysis method of ABAQUS, a finite element analysis (FEA) model to simulate the behavior of CFST columns under both axial load and high temperatures is introduced. The FEA model considered the thermal contact resistance and interaction between the interfaces of concrete and steel, the geometrical and material nonlinear, and the initial imperfection, etc. Conducted the comparison of different load ratio parameters, and considering and not considering the thermal contact resistance. The comparative analysis showed the necessity of considering the thermal contact resistance.