Abstract:Experimental investigations were carried out on reinforced concrete stub columns (RCSCs) subjected to quasi-static loading after exposing to standard fire. The fire exposure cases chosen for study were– a) exposed to 4-faces (1 specimen), b) exposed to three faces (2 specimens), exposed to two adjacent faces (1 specimen), and d) no exposure to fire (1 specimen). The effects of fire exposure case and horizontal loading direction on failure pattern, shear strength, stiffness, ductility and hysteretic energy dissipation of the specimens were investigated. A finite element model was also developed to simulate the temperature distribution during fire exposure period and behavior under the post-fire push-over loading. The developed FE model was validated with experimental test results. The results showed that decrease in number of fire exposure faces leads to decrease in the maximum sectional center temperatures and decrease in reduction in shear strength and hysteretic energy dissipation after a fire of 120 minutes. The maximum sectional center temperatures in the columns, after a fire of 120 minutes, were measured and found to be 341℃, 267℃ and 251℃, 191℃ for the 4-faces, two kinds of 3-faces, and 2-adjacent-faces fire exposure, respectively. Compared with the RCSC without fire, the shear strength of the RCSCs after exposure to 4-faces, two kinds of 3-faces, and 2-adjacent-faces were decreased by 41.2%, 18.6% and 18.8%, 6.6%, while the accumulated hysteretic energy dissipation of stub columns at the end of 1/50 displacement angle cycle decreased by 46.2%, 27.6% and 28.9%, 12.4%, respectively. For the RCSCs exposed to 3-faces fire, the seismic performance of the columns subjected to horizontal load along the symmetrical axis and vertical the symmetrical axis was found nearly same. The proposed numerical model can predict the temperature development process in the section and the shear strength of the specimens after fire considering different exposure cases.
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