圆钢管约束型钢混凝土柱火灾下与火灾后力学性能与设计

The steel tube confined steel reinforced concrete column is a new type of high performance composite member, in which the steel tube does not bear axial load directly. The fire and post-fire performances of steel tube confined steel reinforced concrete columns differ greatly from those of concrete-filled steel tubular (CFST) columns and steel reinforced concrete (SRC) columns, therefore design methods for CFST columns and SRC columns cannot be directly applied. Up to date, there is no systematic research and design method for fire resistance of this type of member, and the research on residual mechanical behaviors after fire is still a gap. This project will conduct a series of experiments, including tests of temperature distribution, full-scale specimens exposed to fire, and residual mechanical behaviors after standard fire. A refined finite element analysis model basing upon the whole process of fire will be developed to investigate the temperature distribution, confinement effect, fire resistance and residual mechanical behaviors. Fire safety design methods will be proposed for various fire-protection ratings and loading modes, and technical assessment systems for the evaluation and rehabilitation after fire exposure will be established. The research shall be beneficial to reveal the scientific issues, e.g., stress mechanism, confinement effect and failure modes, among steel tube confined steel reinforced concrete columns in and after fire exposures. It may also contribute to the engineering practice of steel tube confined steel reinforced concrete columns and to boost the development of innovative high performance building structures in China.

钢管约束型钢混凝土柱是在钢管中内置型钢混凝土，但钢管不直接承受外荷载的一种新型高性能组合构件。钢管约束型钢混凝土柱与钢管混凝土柱及型钢混凝土柱抗火性能和灾后性能差异较大，不可直接套用。国内外尚缺乏对该类构件抗火性能的系统研究与设计方法，火灾后剩余力学性能的相关研究尚为空白。项目将开展系列圆钢管约束型钢混凝土柱温度场试验、火灾下足尺明火抗火性能试验、标准火灾作用后剩余力学性能试验研究；建立基于受火全过程的精细化有限元分析模型，研究圆钢管约束型钢混凝土柱温度分布、约束效应、耐火极限以及剩余力学性能；构建满足不同防火设计等级、不同受力模式的抗火设计方法，建立火灾后圆钢管约束型钢混凝土结构损伤与评估技术体系。上述工作将有利于揭示钢管约束型钢混凝土柱在火灾下与火灾后的受力机理、约束效应与破坏模式等关键科学问题，推进钢管约束型钢混凝土结构的应用进程，促进我国新型高性能建筑结构产业的蓬勃发展。

钢管约束型钢混凝土柱作为（超）高层建筑以及大跨公共建筑中的主要承重构件，在火灾中一旦失效，可能导致严重的整体结构倒塌，并造成巨大的生命财产损失，故其防火设计必不可少。项目从温度场、火灾下力学性能和标准火灾作用后剩余力学性能三个方面，开展了对钢管约束型钢混凝土柱抗火性能的系统研究：完成了钢管约束型钢混凝土柱试件的温度场试验和有限元分析，提出了钢管约束型钢混凝土柱中外部钢管温度和混凝土温度的简化计算公式；完成了足尺钢管约束型钢混凝土柱试件的耐火极限试验和有限元分析，建立了钢管约束型钢混凝土轴压构件、压弯构件耐火极限的简化计算公式；完成了火灾后钢管约束型钢混凝土柱试件的剩余力学性能试验和有限元分析，建立了火灾后钢管约束型钢混凝土柱中的强度承载力、稳定承载力、压弯承载力以及刚度的简化计算方法。项目为钢管约束混凝土构件抗火性能设计提供了计算方法与设计建议，完善了钢管约束混凝土结构的分析理论与设计体系。