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Weiyi Kong,Chuanguo Fu,Weiqing Liu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2
According to the characteristics of a reinforced concrete beam supporting column transfer structure, two types of full-size beam supporting column transfer structure joints are designed, and the post-fire residual mechanical behavior is tested. We observe the deformation and crack propagation of joint specimens under load, construct the load-deflection curve, record the post-fire residual strength and analyze the failure mode. The results show that longer exposure to high temperature is correlated with a smaller residual capacity of the joint units. When the specimens reach the ultimate bearing capacity, cracks form in the A-type joint unit specimens that are aligned with the central axis of the supported column, and several vertical cracks appear in the core area of the joint. The cracks of the B-type joint unit arise primarily on the compression side of the supported column, and many prominent inclined cracks arise in the core area of the joint that extend from the bottom to the compression zone of the transfer beam. Therefore, for structures with a bearing column girder transfer floor, the influence of the change of the internal force distribution on the post-fire load-bearing performance caused by the arrangement of the column should be considered.
Residual Shear Capacity of Reinforced Concrete Beams after Fire Exposure
Yamin Song,Chuanguo Fu,Shuting Liang,Dong Li,Longji Dang,Chongfang Sun,Weiyi Kong 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.11
The mechanical properties of concrete and steel are seriously degraded under high temperature, so that reinforced concrete (RC) members after fire may not be able to satisfy the prescribed performance. In this study, 27 full-scale RC beams were carried out shear tests to investigate the shear behaviour after fire. A total of 20 beams were subjected to fire on three sides in accordance with ISO 834 standard fire curve, and the remaining 7 beams (which were not subjected to fire) were employed as a reference. The influences of fire time, stirrup ratio, shear span ratio, longitudinal reinforcement ratio, and preloading (40% loading level) were considered. The experimental results indicated that the shear failure mode of the RC specimens after fire exposure was similar to that of the reference specimens. Both the residual shear load bearing capacity and stiffness of the RC beams decreased after being subjected to fire. The loss of shear bearing capacity increased with the heating time. In addition, the ultimate load bearing capacity of specimens with stirrups subjected to the same fire exposure time decreased with an increasing shear span ratio.