高性能复合材料加固钢筋混凝土框架结构抗连续倒塌性能研究

TThe progressive collapse of building structures due to accidents has become a serious threat to the public safety. Thus, the anti-progressive collapse ability of the structures should be paid more attention..ECC (Engineered Cementitious Composite) is a new engineering cement-based composite material. It has properties of tensile strain hardening and high ductility. SFCB（Steel-FRP composite bar）is a composite bar which has stable secondary stiffness. The two kinds of material have a good prospect of strengthening the frame structures to improve the progressive collapse resistance performance..The following subjects will be investigated. 1) Based on energy balance principle, the requirements of nonlinear resistance of anti-progressive collapse frame structure, which have stable and controllable secondary stiffness, will be analyzed. And the resistance requirement principles of strengthening structures with SFCB and ECC in different collapse mechanisms are put forward. 2) By means of the quasi-static experiments and nonlinear numerical analysis, the research on the resistance, hysteretic restoring force behavior, and damage control of beam-slab system, column, and joints, strengthened by two kinds of high performance material, will be conducted. 3) On the basis of the above results, the anti-progressive collapse design method of the frame structures, which is strengthened by high performance materials, will be established.

结构在意外荷载作用下的连续倒塌严重威胁公共安全，如何提升结构抗连续倒塌性能急需引起重视。ECC(Engineered Cementitious Composite)材料的拉应变硬化、高韧性和SFCB（Steel-FRP composite bar）的稳定二次刚度等优点使它们可用于加固钢筋混凝土框架结构以提升其抗连续倒塌性能。本课题将针对以下内容进行研究：1）基于能量平衡原理，对具有稳定可控二次刚度的钢筋混凝土框架结构进行非线性抗力需求分析，提出不同倒塌机制下对SFCB和ECC联合加固结构的抗力需求准则。2）通过拟静力试验和非线性数值分析，对高性能复合材料联合加固的钢筋混凝土梁（板）结构体系、关键柱和节点进行抗力、恢复力特性和损伤可控研究。3）建立高性能复合材料联合加固后具有二次刚度框架结构的抗连续倒塌设计方法。

建筑结构倒塌事故往往造成重大的人员伤亡和财产损失，因此结构抗连续倒塌特性研究仍是当前研究的热点问题。为了提高普通钢筋混凝土结构的连续倒塌抗力，从框架结构的抗力需求出发，本项目从材料、复合和构造三个层面分别提出了提高框架结构倒塌抗力的三个方法。具体设想分别为采用传统钢筋与新型FRP复合材料组合的SFCB作为结构纵筋、利用高延性纤维水泥基复合材料（ECC）替换混凝土对结构加固、设置新型起波钢筋（KB）提早激发悬链线机制。基于上述构想，本项目首先设计并开展了上述三种系列的拟静力模型试验。试验研究分别发现了SFCB、ECC和KB的应用均能够提高试件在压拱机制和悬链线机制下的承载力和变形能力；为了最佳发挥复合材料的优势，兼顾结构承载力和构造性能提出了控制SFCB的最大二次刚度比宜为0.30的建议；在此基础上，又对上述结构连续倒塌行为进行了理论分析和非线性数值模拟。提出了反弯压力拱等系列力学模型，建立了压拱峰值承载力等系列计算方法。推导了结构在梁机制、压拱机制和悬链线机制下的承载力计算公式，揭示了上述三种方法提高各阶段承载力的机理。通过参数分析揭示了各因素对结构承载力的影响规律，并对比了新旧GSA规范在评估结构连续倒塌性能方面存在的异同点。本研究提出了这三种思路的设计理论，为新型复合材料及新型构造钢筋在混凝土框架抗连续倒塌设计中的应用提供了依据。