Performance Of Steel Reinforced Concrete (SRC) Column And Portal Frame After Exposure To Fire

A thorough study on performance of steel reinforced concrete (SRC)structures under the coupled loading and full-range fire with both heating andcooling, is of theoretical and applied significance for fire safety design andassement of a SRC structure after fire exposure. Performance of SRC columnsand SRC column to reinforced concrete (RC) beam portal frames are thusinvestigated after exposure to fire.The main research work and results of the current thesis is as follows:1. Experiments were conducted on five SRC columns, ten SRC column toRC beam portal frames after exposure to fire. The time relationships oftemperature field of characteristic cross-section, deformations of columns andbeams, typical failure modes and residual load bearing capacities of the SRCcolumns and SRC column to RC beam portal frames were analyzed.2. Several subroutines, including material constitutive relations conversion,concrete thermal creep strain, concrete instantaneous thermal strain andexplosive spalling of high strength concrete were developed. Finite elementanalysis (FEA) models of SRC columns and SRC column to RC beam portalframes under the full-range fire were then established and were verified by thetests.3. Based on the verified FEA models, the temperature distributions,deformations, failure modes, strain distributions, internal force redistributionand residual load bearing capacities of the SRC columns and SRC column to RCbeam portal frames under the combined fire and loading sequences wereanalyzed.4. Influences of various parameters on the residual load bearing capacitycoefficient of the SRC columns were calculated. It is found that, in general,heating time, perimeter of column section, slenderness ratio and concretestrength clearly affect the residual load bearing capacity coefficient of the SRCcolumns. Influences of various parameters on the equivalent length of the SRCcolumn in the SRC portal frames after exposure to fire were also investigated. It is found that the heating time, beam-column linear stiffness ratio, columnconcrete strength, stiffness ratios of the horizontal restraint spring, the verticalrestraint spring and the rotational restraint spring clearly affect the equivalentlength of the SRC column in the SRC portal frames after fire. Tables forcalculating the residual load bearing capacity coefficient of the SRC columns, aswell as the equivalent length of the SRC column in the SRC portal frames afterfire were proposed finally.