基于整体可靠度的钢框架连续倒塌状态评估及性能设计对策

Through theoretical analysis, model test and numerical simulation, the limit state equation for progressive collapse of steel frame with structural resistance, as the main control parameter, is established by alternate load path method, based on the full study on the performance of anti-collapse mechanism. Then, combined with the performance objectives, the robustness index system for progressive collapse of steel frame is built by means of multi-parameter analysis. Based on the overall reliability theory, the collapse failure structural model including multi-level uncertainty parameters and corresponding probability distribution functions is constructed through the damage analysis and collapse risk evaluation. After that, the collapse failure probability of structure and the reliability index system with ability oriented are obtained, which could be used for quantitative state evaluation of structural performance. From the expression of demand and capacity factor based on the overall reliability, the capacity spectrum relationships between overall structure, anti-collapse substructure and individual components are established. So, the key design parameters influenced on the progressive collapse resistance of steel frame could be determined, and the corresponding design method of performance is put forward. This project provides theoretical and experimental basis for state evaluation and performance design for progressive collapse of steel frame. And it is beneficial supplement for structural reliability theory, also the important reference of progressive collapse limit state (the third limit states) on the application to the relevant design standards, which has good scientific significance and application value.

以钢框架为研究对象，通过理论分析、模型试验和数值模拟，采用备用荷载路径方法，在充分研究抗倒塌机制性能的基础上，构建以结构抗力为主要控制参数的结构连续倒塌极限状态方程，通过多参数分析并结合状态性能目标，建立钢框架连续倒塌的鲁棒性指标体系；基于整体可靠度理论，通过损伤分析及倒塌风险评估，构建基于多层次不确定性指标参数及相应概率分布函数的结构倒塌失效模型，获得结构的倒塌失效概率，并建立以能力需求为导向的可靠性指标体系，定量评价结构的性能状态；采用基于整体可靠度的需求能力系数表达式，建立整体结构、抗倒塌子结构、单个构件的能力谱关系，确定影响钢框架抗连续倒塌能力的关键设计参数，提出相应的性能设计方法。本项目为钢框架连续倒塌的状态评估及性能设计提供理论和试验依据，是对当前结构可靠度理论的有益补充，为第三种极限状态——连续倒塌极限状态在相关设计标准中的应用提供重要借鉴，具有很好的科学意义和应用价值。

连续倒塌是指由于意外事件造成结构的局部破坏，并引起连锁反应向结构 其它部分扩散，造成和结构初始破坏范围不成比例的破坏，甚至导致建筑物的大范围坍塌。连续倒塌所具有的非比例倒塌特点往往伴随着严重的生命财产损失。.（1）通过理论分析构建了双跨组合梁在集中荷载作用下的非线性力学模型，详细分析了其在连续倒塌过程中5个不同性态阶段（弹性阶段、弹塑性阶段、塑性阶段、过渡阶段及悬链线阶段）的抗力转换机理，初步建立了以结构抗力为主要控制参数的结构连续倒塌极限状态方程，实现了对平面钢框架连续倒塌性能的完整力学描述。.（2）对不同连接形式的组合梁-柱子结构进行了共计15个试件的连续倒塌试验研究，在考虑非线性、大变形、钢材断裂、材料损伤等分析难点后，采用ABAQUS/Explicit显式动力准静态方法构建了试件模型的精细化数值模型和多尺度数值模型，对影响结构抗连续倒塌能力的性能指标逐一进行分析，得到其影响规律后提出了相应的结构设计方法和性能提升对策。.（3）通过构建不同刚度的梁柱节点简化模型，定量描述了结构抗力和构件抗力之间的关系规律，从而实现了对局部构件受损后结构的鲁棒性评价。.（4）结合通用的可靠度理论计算公式及数值分析方法，以按规范设计的空间钢框架结构作为研究对象，进行了地震作用下结构的连续倒塌可靠度分析，构建了地震作用下的结构倒塌失效模型，获得了结构的倒塌失效概率和对应的可靠度指标，定量评价了结构的性能状态。.本项目基本完成了预期研究目标。