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.

高温下，混凝土和钢材的机械性能会严重降低，因此火灾后的钢筋混凝土（RC）构件可能无法满足规定的性能。在这项研究中，对27个全尺寸RC梁进行了剪切试验，以研究火灾后的剪切行为。根据ISO 834标准着火曲线，总共对20条光束在三个侧面进行了射击，其余的7条光束（未受到射击）用作参考。考虑了着火时间，箍筋比，剪切跨度比，纵向增强比和预载（40％载重水平）的影响。实验结果表明，钢筋混凝土试样在火灾后的剪切破坏模式与参考试样相似。钢筋混凝土梁遭受火灾后，其残余剪力承载力和刚度均下降。剪切承载力的损失随着加热时间的增加而增加。此外，在相同的火暴露时间下，带有箍筋的试样的极限承载力随着剪切跨度比的增加而降低。