FRP加固非延性钢筋混凝土框架结构抗倒塌性能分析与评定

Nonductile reinforced concrete (RC) frames have a high risk level of severe damage or collapses in the future strong earthquakes. And there is an urgent need to evaluate collapse resistance of those structures and then seismic strengthen such existing frames. Quantification of resistance for collapse prevention and probability of collapse of FRP strengthened RC frames are the key scientific problems in seismic strengthening of concrete structures. Nonductile RC frames strengthened with FRP are the research object of this this project, the failure modes of sidesway incremental collapse and vertical progressive collapse of FRP strengthened RC frames are made thorough investigations on. The global seismic performance factors are used to quantify sidesway collapse resistant capacity of RC frames strengthened with FRP, and reasonable FRP retrofitted positions are determined according to sideway incremental collapse modes; the adjusted collapse margin ratio and the demand-capacity-factor method are jointly utilized to comprehensively evaluate if the consistent probability levels of seismic collapse and the performance objectives of collapse prevention of FRP strengthened RC frames could be achieved, and reasonable FRP retrofitted scheme for resisting sideway collapse are derived. The analysis results are verified and validated by substructure pseudo-dynamic test data. Structural robustness indices are used to quantify vertical progressive collapse resistant capacity of FRP strengthened RC frames, and the key element to be removed which is critical to structural global performance is identified; destructive collapse test of RC beam-column sub-structures considering catenary action is conducted to investigate the mechanism of arch and catenary action , then a FRP retrofitted scheme for improving vertical progressive collapse resistance is proposed. The results can provide theory basis for the design method for FRP seismic strengthened nonductile RC frames.

非延性钢筋混凝土框架结构在强震作用下存在较高的倒塌风险，急需对其进行抗倒塌性能评估并加固。定量评估加固后结构的抗倒塌能力及倒塌失效概率是结构加固的关键科学问题。本项目以FRP加固非延性钢筋混凝土框架结构为研究对象，分别针对侧向和竖向倒塌两种失效模式进行分析。采用结构整体抗震性能系数定量评估FRP加固结构的抗侧向倒塌能力，并确定加固位置；采用结构调整倒塌裕度比和位移需求能力系数法，对加固后结构是否具有一致的抗侧向倒塌概率风险水准和能否满足“临界倒塌”性能目标进行概率评定，给出结构抗侧向倒塌加固方案，并用结构拟动力试验进行验证。采用结构鲁棒性指标定量评估FRP加固结构的抗竖向倒塌能力，确定关键构件；通过考虑悬索作用钢筋混凝土梁柱子结构抗倒塌性能试验，研究FRP加固约束梁的压拱机制和悬链线机理，给出结构抗竖向倒塌加固方案。项目成果可为FRP对RC框架结构进行整体抗震、抗倒塌加固提供理论依据。

非延性钢筋混凝土框架结构在强震作用下存在较高的倒塌风险，急需对其进行抗倒塌性能评估并加固。本项目以FRP加固非延性钢筋混凝土框架结构为研究对象，分别针对侧向和竖向倒塌两种失效模式进行了分析。本文的主要研究工作和取得的成果如下： .1）设计并完成了一榀二层二跨FRP加固非延性钢筋混凝土框架子结构拟静力试验，揭示了FRP加固非延性框架在拟静力荷载作用下的破坏机理，研究了其承载力、延性、耗能性能。.2）基于Abaqus建立了FRP加固非延性框架的多尺度模型，并将其与试验结果进行对比验证。采用改进的双参数地震损伤模型，计算FRP加固非延性框架结构各层次在地震作用下不同时刻的损伤值，研究其侧向倒塌失效模式。.3）为了定量评定FRP加固RC框架结构的抗侧向倒塌能力，本文引入了反应修正系数。建立了试验框架的原型框架有限元模型并以结构层数为参数，采用弹塑性静力分析了不同层数框架遭受六、七、八和九级不同加速度作用下其结构反应修正系数，以评定其整体抗倒塌能力。.4）提出了基于概率的CFRP加固非延性钢筋混凝土框架结构的抗震性能评定方法。基于OpenSees平台，评定了加固框架的抗震性能。研究表明，CFRP加固的非延性钢筋混凝土框架结构抗震性能是符合要求的，且留有安全储备。.5）完成了承重构件失效后，FRP加固约束梁的悬链线机制试验。获得了荷载位移曲线，分析了压拱和悬链线阶段受力机理和竖向倒塌失效模式。.6）采用塑性分析法，推导了压拱阶段承载力计算公式；根据力平衡原理，研究了悬链线阶段的承载力计算方法，从而能够估算结构的抗竖向倒塌能力。