The Numerical Simulation On Residual Bearing Capacity Of Steel Tube Reinforced Concrete Column Structure Under Sustained Loading After Fire

The present development of building is dominated by high-level, high-rise buildingconstruction; the traditional steel structure is no longer the designer’s primate choice, dueto its low fire resistance, poor corrosion resistance and high maintenance cost. While theemerging steel tube reinforced concrete column structure (SRC) is gradually paid greatattention by people with its high bearing capacity, fire resistance and low cost advantages.During the period of building service, the influence of the fire is so enormous that canmake the bearing parts of building damaged. The evaluation of buildings after fire is alsovery important from the perspective of economic and security consideration. So theresearch of residual bearing capacity of SRC after fire has strong practical significance.This research content is divided into the following several aspects:In the first instance, ISO-834standard heating up curve is chosen as the temperaturechange rule of thermal analysis for it’s close to the actual fire, and the thermal parameterof concrete and steel have been determined respectively for the purpose of calculating thetemperature distribution in heating process of SRC.Secondary, the constitutive relations and failure criteria of concrete and steel in theprocess of the analysis have been selected through summarizing existing research resultsat home and abroad, while the contrast test model is established to verify effectiveness.Once more, the finite element model of SRC after on three or four sides by the firehas been established and the residual bearing capacity has also been calculated with finiteelement software ABAQUS as the research tools. Then the influence of different factorson the bearing capacity is analyzed. Studies have shown that SRC bearing capacity afterfire losses of more than40%, the influential factors contains flame exposure time,coefficient of position, steel ratio, reinforcement ratio and Slenderness ratio.Eventually, by way of multiple regressions, the formula of residual bearing capacityof SRC after fire in all faces is summarized which is based on the existing formula.