配置Fe-SMA的钢筋混凝土梁火灾后受力性能试验研究OA

Iron-based shape memory alloy(Fe-SMA)rebars embedded in reinforced concrete(RC)beams can be activated at fire exposure to create prestress and improve the post-fire mechanical performance.To study the mechanical properties of hybrid Fe-SMA/steel RC beams,post-fire bending tests were conducted on 16 full-scale specimens,including two ambient-temperature controls and 14 beams exposed to fire for 1.0 h or 1.5 h under load levels of 0.3 and 0.5.The effects of Fe-SMA replacement(0-3)and concrete cover thickness(25 mm and 35 mm)were investigated.The results show that,under sustained loading,increasing cover thickness alone does not significantly reduce the rebar temperature due to fire-induced cracking.Replacing part of the tensile reinforcements with 6%prestrained Fe-SMA rebars reduces the section heating rate during 60-90 min of fire exposure.Fe-SMA reinforcement increases the residual load capacity by up to 17.9%compared with conventional RC beams.With two Fe-SMA rebars,the residual capacity after 1 h fire exposure at a load level of 0.3 is slightly higher than that of the ambient control.Partial recovery of initial stiffness is observed at the 0.3 load level,whereas stiffness improvement becomes limited at the 0.5 load level and 1.5 h fire exposure due to the weakened recovery stress effect.