FRP约束混凝土梁跨中塑性铰延性性能分析

Analytical Investigation of Ductility of the RC Beams with Plastic Hinge FRP-Wrapped

目的确定影响FRP约束梁塑性铰延性的主要因素.方法采用ACI440.2R-08提供的FRP约束混凝土的应力应变关系,编制程序计算分析了约束区截面在屈服和极限状态下的延性随配筋率及包裹量的变化关系.结果计算显示低配筋梁在低包裹量时延性提高幅度为40%左右,高配筋梁在高包裹量时提高320%以上;与传统抗弯加固方法(受拉底面粘贴FRP布)联合使用时,延性有显著改善,其中低配筋梁延性能达到未抗弯加固时的水平.结论约束区长度是影响FRP约束对梁的跨中塑性铰的形成和发展的主要因素,设计时需要考虑采用合理的约束区长度.

In order to define the factors affecting the ductility of beams with mid-span FRP-wrapped,the ductility of the RC beam with plastic hinge at mid-span wrapped by FRP is computed and analyzed,employing the theory the stress-strain relationship of FRP-confined concrete proposed by ACI440.2R-08.The relationship between curvature ductility coefficient and steel ratio and confinement effect is focused.Calculations indicate that the enhancement of ductility of low-steel-ratio beams is notable with low confined effect,up to about 40% ,while that of high-steel-ratio beams with high confined effect is more than 320% .It also indicates that the ductility of beams with both flexural strengthening and plastic hinge FRP-wrapped will get notably increased.The ductility of low-steel-ratio beams can reach the level of non-flexural strengthening.The length of FRP-wrapped zone is regarded to be the most important factor on the form,development,and rotation capacity of plastic hinge at mid-span induced by the wrap.Reasonable length should be adopted during designing.