FRP约束钢筋混凝土柱中FRP与钢筋相互作用机理：试验和理论研究

本课题提出FRP约束钢筋混凝土柱中FRP与钢筋相互作用机理的研究。对FRP约束钢筋混凝土柱进行轴压试验研究，考察截面形状、纵筋配筋率、FRP厚度、加载方式等因素对柱子轴压性能的影响。聚焦FRP与钢筋的相互作用机理，研究FRP对纵筋提供的侧向支撑刚度与FRP自身刚度的关系，基于“弹簧梁”有限元模型，模拟FRP约束条件下钢筋的受压屈曲行为。基于有限元模型进行参数分析，提出侧向支撑作用下（FRP约束效果）钢筋的受压屈曲应力-应变关系模型。基于DIC摄像应变测量技术获得的三维FRP应变场分析，提出FRP与钢筋的相互作用对FRP断裂应变影响的经验公式。提出考虑FRP与钢筋相互作用效果的FRP约束钢筋混凝土柱轴压强度模型。进行FRP加固钢筋混凝土柱拟静力试验，聚焦FRP和钢筋的相互作用对荷载-位移滞回曲线尤其是下降段曲线的影响，在试验以及有限元参数分析的基础上,提出考虑二者相互作用影响的恢复力模型。

This study is concerned with the interaction mechanism between FRP jacket and internal reinforcing bars in FRP-confined RC columns. This study presents experimental studies on axial compressive behavior of FRP-confined RC columns, with emphases on the influence of main parameters (section shape, reinforcement ratio for longitudinal bars, jacket thickness, loading scheme) on the overall compressive behavior. Focusing on the interaction mechanism between FRP and reinforcing bars, the buckling-restraining effect provided by FRP jacket is connected with the stiffness of FRP jacket itself. The compressive behavior of laterally-supported longitudinal reinforcing bars in FRP-confined RC columns is simulated by the proposed “Beam with Springs” model. A stress-strain model including buckling effect is then proposed for laterally-supported reinforcing bars. Based on 3D strain field analysis obtained by DIC measuring method, an empirical expression for the ultimate rupture strain of FRP jacket is proposed. With the new knowledge on buckling behavior of reinforcing bars and the rupture strain of FRP, an axial compressive strength mode for FRP-confined RC columns is proposed. Seismic test on FRP-confined RC columns is then conducted, focusing on the influence of the interaction mechanism on the overall hysteretic load-displacement curves, especially the post-peak descending portion of the load-displacement curves. A restoring force model is finally proposed for FRP-confined RC columns considering the interaction mechanism between FRP jacket and reinforcing bars after parametric studies through tests and FE modeling.