非抗震RC空间框架连续倒塌加固破坏机制与设计方法研究

There are only few buildings designed to resist progressive-collapse among the active buildings of 56 billion square meters in China. So a large number of buildings need to be strengthened for resisting progressive-collapse. The collapse-resistance behaviors and integral performances of some RC spatial frame substructures, which were strengthened with high performance ferrocement laminate and bonded steel plates because of their technical advantages, were analyzed under the failure of their key columns. The arch action, plastic hinge, mechanical hinge, catenary action, and tensile membrane action of the substructures were studied under the different strengthening methods and different failure states. At the same time, transfer routine and distribution mechanism of the collapse loads were analyzed. The influence of progressive-collapse strengthening on collapse zone, associated zone, and intact zone of the prototype structures was analyzed, and the criterions of regional division about collapse zone, associated zone, and intact zone of the prototype structures, in which model substructures were filled, were proposed. The physical measure indexes and the requirements of bearing capacity were studied when different failure mechanism appeared. The collapse criteria and analysis models of collapse strengthening were proposed under different failure mechanism. From the integral bearing capacity of the prototype structure, the zoning design and calculation methods of progressive-collapse strengthening were given. At the same time, the collapse performance analysis method was given. The research findings would provide theoretical basis and experimental data for RC structure's progressive-collapse strengthening and give reference to establishment of the related criterions.

我国现役560亿平方米建筑中经过抗倒塌设计的屈指可数，大量建筑需进行连续倒塌加固。项目考虑加筋高性能砂浆—粘钢联合加固的技术优势，采用该技术对数榀钢筋混凝土非抗震空间框架子结构模型进行连续倒塌加固，研究关键柱失效状态下加固子结构的倒塌破坏机制和整体受力性能；分析不同加固方式、不同失效状态下结构压拱效应、梁铰机制、悬链线效应、薄膜作用机制，以及倒塌荷载的传递途径和分配机制；进而将模型子结构放入原型结构中，模拟分析加固对原型结构倒塌域、关联域、完整域的影响；提出结构倒塌域、关联域、完整域的划分原则；研究不同破坏机制出现时的物理度量指标、构件承载力要求，提出对应倒塌破坏判定准则和倒塌加固分析模型；从结构整体受力性能角度提出连续倒塌加固“按域设计”方案、承载力计算和倒塌性能分析方法。项目的完成将为RC结构抗连续倒塌加固研究提供宝贵的试验数据和理论基础，为我国相关规范的制定提供参考。

RC框架在我国城市建筑特别是大型公共建筑中应用广泛，服役期间可能会遭受诸如煤气爆炸、恐怖袭击、火灾、撞击、地震等偶然荷载，造成结构局部破坏或损伤，进而引发连续性倒塌。目前，现役建筑绝大部分未进行抗连续倒塌设计，为确保建筑结构在偶然荷载作用下不发生连续倒塌，项目以申请人提出的新型加固方法“加筋高性能砂浆(HPFL)-粘钢联合加固技术(BSP)”为基础，对加固后中柱失效框架，边柱失效框架，和角柱失效框架抗连续倒塌机理进行研究。首先，提出梁柱子结构抗力机制划分方法，基于已完成的梁柱子结构试验建立ABAQUS有限元模型，对结构抗力机制进行量化研究。通过对收集的105个梁柱子结构试验数据进行分析，提出梁柱子结构各抗力机制的荷载和位移计算模型。基于能量守恒原则提出结构倒塌破坏判定准则，并根据各机制抗力理论计算模型，建立了倒塌点理论计算公式。其次，设计并完成了三榀HPFL-BSP加固边柱失效子结构倒塌试验，三榀HPFL-BSP加固角柱失效子结构倒塌试验，及两榀次梁加固角柱失效子结构倒塌试验研究。试验研究结果表明，边柱失效子结构梁全部发生受弯破坏，而角柱失效子结构除对比框架和梁加固框架的梁发生受剪破坏外，其余均发生受剪破坏。相同位移下，加固后框架耗能能力，峰值静力抗力和动力抗力均得到显著提高，峰值抗力提高幅度在9%~34%之间。依据试验结果建立了加固框架峰值抗力预测模型。通过建立试验框架的有限元模型，分析了不同加固方法下，框架荷载分配机制，提出框架抗力机制统一划分准则并进行量化分析，建立了基于数据驱动的承载力预测模型。最后，建立框架整体模型，基于供需比提出倒塌域划分准则，并对整体框架进行破坏域划分，并采用基于风险评估的不确定性分析方法对不同加固方法下结构的连续倒塌性能进行评估。项目研究揭示了加固结构连续倒塌破坏机理，推动了抗连续倒塌研究的进展，并对该加固技术的推广应用起到良好的促进作用。