局部火灾下多层钢-混凝土组合空间框架结构抗火性能与设计方法

Presently, studies on the fire performance of steel-concrete composite plane frame structures and steel column-steel concrete composite floor spatial frame structures on the foundation of steel columns have been carried out to an extent domestic and abroad. However, studies on the fire performance of steel-concrete composite spatial structures on the foundation of concrete-filled steel columns aren't commonly seen. Therefore, theoretical analyses and experimental investigation on the fire performance and designing method of steel-concrete composite spatial frame structures on the basis of concrete-filled steel columns at local high temperature will be included in this project. By conducting fire performance tests and collapse analysis of the full scale model of a three-storey three-bay steel-concrete composite spatial frame structure at local fire of partial compartment or single-floor, the nonlinear finite element analysis theory of steel-concrete composite spatial frame structures at local high temperature will be obtained; the influence of axial compression ratio of columns, beam-to-columns stiffness ratio, beam-to-column strength ratio, level expansion deformation of beams and axial deformation of columns on the mechanical performance of the steel-concrete composite spatial frame structures will be discussed; the failure mode, spatial effect and the most adverse situation of steel-concrete composite spatial frame structures under different fire conditions will also be investigated. Consequently, the simplified fire resistance analysis method of steel-concrete composite frame columns and composite frame beams under local fire will be presented and the designing and structural measures of fire resistance of steel-concrete composite spatial frame structures under local fire will be achieved.

目前国内外学者对钢-混凝土组合平面框架结构和以钢柱为基础的钢柱-钢混凝土组合楼盖空间框架结构开展较深入的抗火性能研究，而对以钢管混凝土柱为基础的钢-混凝土组合空间结构抗火性能缺乏研究。本项目针对以钢管混凝土柱为基础的局部火灾下多层钢-混凝土组合空间框架结构的抗火性能和设计方法开展系统深入的试验研究与理论分析。通过开展3×3跨3层钢-混凝土组合空间框架结构足尺模型在局部隔间或楼层火灾下抗火性能试验研究，建立局部火灾下钢-混凝土组合空间框架结构非线性有限元分析理论，分析高温下柱轴压比、梁柱线刚度比、梁柱抗弯强度比、梁水平膨胀变形和柱轴向变形对钢-混凝土组合组合空间框架结构力学行为的影响，探讨不同火灾工况下钢-混凝土组合空间框架结构破坏模式、空间效应和最不利情况，建立局部火灾下钢-混凝土组合框架柱、框架梁抗火性能简化分析方法，提出局部火灾下多层钢-混凝土组合空间框架结构抗火设计方法和构造措施。

越来越多的火灾事件，使得建筑结构抗火研究成为当前土木工程领域的热点。目前国内外学者对钢-混凝土组合平面框架结构和以钢柱为基础的钢柱-钢混凝土组合楼盖框架结构开展较深入的抗火性能研究，而对以钢管混凝土柱为基础的钢-混凝土组合框架抗火性能缺乏研究。本项目针对以钢管混凝土柱为基础的局部火灾下多层钢-混凝土组合框架结构的抗火性能和设计方法开展系统深入理论分析。通过在以底面受火钢筋混凝土简支板、三面受火钢筋混凝土简支梁和连续梁、四面受火圆钢管混凝土柱以及局部受火三层三跨钢柱-组合楼盖空间框架抗火性能分析的基础上，开展了局部受火三层三跨“强梁弱柱”和“强柱弱梁”型足尺钢管混凝土柱-钢筋混凝土梁组合框架的抗火性能分析，分析高温下节点刚度退化、构件内力重分布及截面应力重分布规律，提出了局部火灾下多层钢-混凝土组合框架结构以钢管混凝土柱及节点防火保护为主、钢梁防火保护为辅的抗火设计方法和构造措施。本项目研究成果将为丰富和完善结构抗火设计规程提供参考。