全过程及非均匀受火下内配型钢的钢管混凝土构件抗火性能

The concrete-filled steel tubular member with internal profiled steel is the typical and common type for columns of the superhigh-rise buildings currently, and there are rather few researches on its fire resistance and fire design approach. This project will study the mechanical mechanism and design approaches of concrete-filled steel tubular members with internal profiled steel exposure to standard fire,non-uniform fire and overall stage fires with ascending and descending temperature. The fire experiments will be performed of this type of composite members under various fire scenes and combined axial load. The mechanical behavior and mechanism of those three components, that are inner profiled steel, core concrete and steel tube, should be investigated based on experiments and numerical simulation. A 3-D finite element analysis (FEA) model will be developed to simulated the performance of the tested specimens. The test results are used to verify the FEA model. A micro detailed analysis should be performed to reveal the mechanical behavior, deformations and typical failure modes of the composite members under various fires and combined loads. Parametric studies carry out in a common scale for practical engineering using the validated FEM model under various typical fires and loads. The systematical fire resistance design approaches and formulas will be achieved to perfect the design theory and practical engineering for this type of composite members.

内配型钢的钢管混凝土构件是目前超高层建筑中常用的柱构件形式，目前国内外尚缺少其抗火性能的研究及设计方法。本课题以研究内部配置型钢的钢管混凝土组合构件在考虑升降温全过程火灾及非均匀火灾作用下的工作机理和设计方法为目标，进行各典型受火工况下该类组合构件的试验研究，细致分析和测试构件受火及受力全过程中内部型钢、核心混凝土及外钢管三者之间的受力特性，明晰其工作机理。建立基于三维弹塑性理论的有限元数值模型对试验试件进行模拟，用试验数据来校验数值模型，进一步对该类构件的受火性能及受力特性进行微观分析，细致剖析其在各种受火及荷载工况下的变形特征和典型的破坏形式。基于前述数值模型，进行工程常用参数范围内此类组合构件在各种典型火灾及荷载工况下力学性能的参数分析，提供内配型钢的钢管混凝土构件的各种火灾工况下的抗火设计方法，为此类结构抗火设计和工程应用提供参考，进一步完善内配型钢钢管混凝土组合构件的设计理论。

本课题以截面形式、火灾荷载比、偏心率及受火工况为典型参数，完成任务书中8个足尺内配型钢钢管混凝土构件火灾下耐火性能试验，系统研究了上述参数对该类柱破坏形态、钢管约束效应、耐火极限等的影响规律。采用ABAQUS计算截面温度场，研究了各组成部件间共同工作机理，剖析和对比了不同受火工况（即均匀受火、三面受火、相对两面受火、相邻两面受火、单面受火）下其耐火性能。对组合柱的含钢率分配进行了计算，给出耐火极限性能发挥最优时含钢率分配的建议值。通过对内配型钢钢管混凝土柱受火后剩余承载力影响系数进行参数分析，给出了适用于该类柱火灾下剩余承载力的计算公式及防火保护层厚度设计方法。基于火灾全过程试验，对考虑降温段的内配型钢钢管混凝土柱的抗火性能进行了研究，分析了火灾荷载比、升温时间比、受火工况、偏心率等参数对火灾后剩余承载力的影响，通过参数分析给出了工程常用范围内该类柱火灾后剩余承载力计算方法。利用FDS火灾动力模型软件，建立了不同热释放速率及起火点数目作用下的火场模型，以此为基础考虑真实火灾效应对内配型钢钢管混凝土柱耐火性能的影响，并与标准升温作用下的该类柱的耐火性能进行对比，为特定场景的火灾后分析评估提供参考。