火灾诱发多层轻钢复合墙体结构失效理论及倒塌仿真研究

Mid-rise cold-formed steel (CFS) structure has the advantages of green environmental protection, energy conservation, low steel consumption and rapid construction speed and shows bright prospects in future. The fire performance of such structures has become an important concern in fire safety engineering. Therefore, a systematically experimental, theoretical and numerical study will be carried out in this project. Firstly, based on the innovative experiments, the mechanical properties of wall panels and the corresponding screw connectors will be investigated at elevated temperatures. Secondly, a simplified theoretical model will be put forward for the load-bearing CFS walls subject to fire exposure from one side. Thus, the fire performance of CFS walls, such as temperature distribution, time-dependent lateral deflection, fire resistance time and failure modes, can be predicted efficiently. Simultaneously, based on AEM method, a refinement numerical method will be proposed to simulate the thermo-mechanical behavior of CFS walls under fire conditions, including the cracking and falling off of wall panels, failure and collapse of wall systems and so on. According to the proposed theoretical and numerical methods, the fire performance and failure mechanism of CFS walls will be analysis and a practical design method for the fire safety of such walls can be developed. Finally, based on AEM method, the fire-induced progressive collapse model of mid-rise CFS wall structure will be developed to investigate the failure mechanism of such structure system under fire conditions. In addition, the element importance of such structure system will be evaluated under vertical loads and the relationship between the fire-induced failure of key structural members and collapse of whole structure will be discussed. Subsequently, some improvements will be put forward to enhance the anti-collapse performance of such structure system. The present research well follows the developing of building industrialization and may provide theoretical and technical support for the popularization and application of green building in our country.

多层轻钢房屋建筑结构具有绿色、节能、环保、用钢量省、施工速度快、易于产业化等特点，在我国具有良好应用与发展前景，而其耐火性能是目前亟需解决的关键问题。对此，本课题首先进行轻钢结构常用建筑板材及其自攻螺钉连接件高温力学性能试验研究；而后，提出单侧受火轻钢复合墙体温度场与变形复杂分布规律以及耐火时间与破坏模式预测的简化理论模型；同时，基于AEM方法，发展轻钢复合墙体受火开裂、板材脱落至墙体倒塌破坏的全过程数值仿真模型；根据上述研究，揭示轻钢复合墙体热力响应规律与受火失效机制，实现复合墙体实用抗火设计；此后，构建火灾诱发多层轻钢复合墙体结构连续倒塌数值仿真模型，确定竖向荷载作用下轻钢结构中复合墙体重要性评价方法，分析结构受火连续倒塌破坏机理，探讨结构中关键墙体受火破坏与整体结构失效的关联性，并通过改进措施提高结构整体抗倒塌能力。本课题顺应国家建筑产业化发展趋势，旨在促进绿色建筑在我国广泛应用。

多层轻钢房屋建筑结构具有绿色、节能、环保、用钢量省、施工速度快、易于产业化等特点，在我国具有良好应用与发展前景，而其耐火性能是目前亟需解决的关键问题。对此，本项目完成了300余次冷成型钢高温后力学性能试验以及500余次冷成型-自攻螺钉连接件高温抗剪试验，提出了相应力学计算模型；完成了16片小尺寸冷成型复合墙体非承重耐火试验，率先考察了碳氢火灾、室外火灾等其他标准火灾环境对冷成型钢复合墙体耐火性能影响；率先将常见等效爆火模型进行了冷成型钢复合墙体足尺模型承重耐火试验验证，对其不适用性进行了机理阐述，并揭示了内置填充层对于冷成型钢承重复合墙体的不利抗火作用机理；提出了ISO834标准火灾作用下轻钢复合墙体温度场与变形复杂分布规律以及耐火时间与破坏模式预测的简化理论模型；同时，基于FEM方法，发展轻钢复合墙体抗火数值仿真模型；根据上述研究，揭示轻钢复合墙体热力响应规律与受火失效机制，实现复合墙体实用抗火设计，被江苏省规程《轻钢龙骨式复合剪力墙房屋建筑技术规程》所引入。此后，构建了多层轻钢复合墙体结构受火倒塌数值仿真模型，并基于线性静力连续拆除构件法进行轻钢整体结构抗倒塌研究；在此基础上，提出了轻钢结构抗连续倒塌构造措施。最后，总结了本项目研究过程中发现以下新科学与技术问题，并提出相应建议。本项目顺应国家建筑产业化发展趋势，旨在促进绿色钢结构建筑在我国的推广与应用。