弦支穹顶结构实际火灾全过程中行为响应机理研究

Suspendome structure is a new-type hybrid spacial structure system，based on the concept of combining cable dome with reticulated shell. However, the prestress and material property of cable and shell stability is sensitive to elevated temperature. Therefore, fire is the main disaster for the suspendome safety. In recent years, there are only a few studies on the fire performance of suspendome. The research on the structural behavior under natural fire is not perfect. Therefore, based on the concept of performance-based design, the temperature field, material property under high temperature, and structural response are studied. First, numerical simulations and parametric analysis are conducted on fire scenarios for suspendome building. The space distribution and development of the temperature field are proposed. The development tendency of the temperature in the cable during the whole process of fire is studied. The practical calculation approach is established. Then, experimental study and theoretical analysis are carried out to investigate the material property and the prestress loss of the prestress cable during the heating and cooling phase. The constitutive model of prestress steel wires under high temperature and the mutative rules of prestress loss of cable are provided. Finally, direct analysis on the mechanical response of structures under natural fire is conducted and the mechanism of damage evolution is revealed. Meanwhile, the evaluating indicator of fire resistance and design suggestion are offered. The achievement of this research will provide theoretical base and technical support for the fire resistant design of suspendome structures.

弦支穹顶结构是将索穹顶结构和网壳相结合而形成的一种新型大空间结构体系。然而钢索预应力、材性和网壳稳定性对温度变化敏感，因此火灾是危及该类结构安全的重要灾害。目前对于弦支穹顶结构抗火性能研究尚处于起步阶段，较少涉及实际火灾全过程结构的性能。本项目基于性能化抗火思想对弦支穹顶结构开展温度场、高温材性和整体结构响应三位一体的研究。首先对弦支穹顶建筑火灾进行仿真模拟和参数分析，给出火灾温度场的空间分布规律与时间发展规律。在此基础上，研究火灾全过程中钢丝束索升降温机理，提出实用计算方法。其次对火灾升降温段预应力钢丝高温材性和钢索预应力损失开展试验研究和理论分析，给出预应力钢丝的高温本构模型和钢索预应力损失规律。最后，对整体结构在火灾中的力学响应进行直接分析，揭示弦支穹顶结构在升降温全过程中的性能演化机理，提出抗火性能评价指标和设计建议，为弦支穹顶结构的抗火设计方法及灾后评估提供理论依据和技术支撑。

弦支穹顶结构由上部单层网壳和下部弦支体系组合而成，传力机制高效，施工难度相对较低，因此得到了广泛应用。弦支穹顶的内部空间较大，如果发生火灾，其火灾特性与普通室内火灾有明显不同。在高应力和不均匀温度场的共同作用下，钢索预应力降低、网壳应力重分布，导致结构稳定性降低甚至整体坍塌。基于上述背景，本项目基于性能化抗火的思想，采用理论分析、数值模拟与试验研究相结合的方法，考虑实际火灾的全过程，对弦支穹顶结构内部火灾温度场的空间分布规律与时间发展规律，火灾升降温段高强钢索的材料特性、升降温计算方法和预应力损失机理，以及整体结构在火灾全过程中的力学响应进行研究。通过研究，给出了大空间实际火灾全过程预应力钢丝束升降温实用计算方法。建立了升降阶段及高温后预应力钢丝本构模型。揭示了火灾升降温全过程预应力钢丝束索预应力损失规律和弦支穹顶整体结构的力学响应机理。提出了弦支穹顶结构抗火性能的评价指标和防火设计建议，并开发了一种弦支穹顶结构性能化抗火评估系统。成果将为弦支穹顶结构及同类结构的抗火设计提供理论基础和技术支撑，具有重要的科学意义和现实价值。

内容获取失败，请点击重试