Experiment Study And Theoretical Analysis Of Src Columns Under Fire Including Whole Process Of Heating And Cooling

To learn the realistic response of steel reinforced concrete (SRC) columns under fire and after fire exposure, considering the influence of loading during the heating-cooling process, experiment study and theoretical analysis have been done in this paper. It is aimed to investigate the performance of SRC columns under fire considering the effect of loading during the heating-cooling process.The main contents are as follow:(1) Research work on the thermal properties, mechanical performances of steel and concrete under high temperature are summarized and analyzed. Based on these work, calculation model for thermal properties and heat mechanical performance of steel and concrete under fire and after fire exposure is determined.(2) Test on the fire resistance of one eccentrically loaded SRC column under ISo-834 fire was done. Results show that fire behavior of SRC columns under fire is not as good as we have expected because of spalling.(3) Tests of three eccentric compression SRC columns were done, considering the influence of loading during the heating-cooling process. ISO-834 standard heating-cooling fire curve was adopted, and constant load was kept during the full heating-cooling process. Developing regularity of the strength and deformation of the specimens were analyzed. It is found that: the failure mode of the specimens after fire exposure with loading effect is quite different with those at room temperature without loading effect; the ultimate bearing capacity and residual strength are closely related to the pre-load level and temperature ascending time; if load large enough , failure in the cooling stage may occur.(4) Under certain assumptions, a general finite element software ANSYS is utilized to establish the model for calculating the temperature field and mechanical performances of SRC columns during the whole period of fire, which is verified by test data. Theoretical results coincide well with the experimental data, confirming the validity of the theory and providing the basis of further parameters analysis and practical design formulas for fire resistance.