高强混凝土剪力墙的火灾行为和灾后性能

The fire resistance performance and post-fire performance of high strength concrete shear walls will be decreased greatly due to the spalling of high strength concrete under elevated temperature, and the bending and shearing out of plane imposed by the adjacent floors. Up to now, research on the fire behaviour and post-fire performance of high strength concrete shear walls is very little. In this project, the fire performance tests of high strength concrete shear walls with displacement restraint out of plane will be carried out. The effects of axial load ratio, load eccentricity, fire exposure cases, wall thickness, concrete curing conditions and so forth on the spalling, failure model and fire resistance of high strength concrete shear walls will be investigated. Subsequently, based on the fire tests and finite element simulation of one-storey high strength concrete shear wall structures, the fire behaviour of high strength concrete shear walls in structures will be revealed quantitatively. Furthermore, Some computer programs will be developed to calculate the fire resistance and the stability of high strength concrete shear walls in fire, and the influence parameters will be analyzed systematically. A simplified calculation method for the fire resistance of high strength concrete shear walls considering spalling will be proposed. Finally, the experimental study and theoretical analysis on the performance of the eccentric compression and earthquake resistance of high strength concrete shear walls after a full-process fire will be conducted, in which the effects of axial load ratio, fire exposure time, fire exposure cases, spalling degree and so forth are considered. A practical calculation method for the residual capacity of high strength concrete shear walls after fire will be developed. This project aims to lay a foundation for fire resistance design and post-fire damage evaluation of high strength concrete shear walls.

高温下高强混凝土的爆裂、相邻楼盖对剪力墙的面外弯矩和剪力等作用会显著降低高强混凝土剪力墙的抗火性能和灾后性能。本项目基于高强混凝土剪力墙的火灾行为与灾后性能的研究成果相对较少的现状，拟进行带面外位移约束的高强混凝土剪力墙的耐火性能试验，考察轴压比、偏心距、受火方式、墙厚和养护制度等对高强混凝土剪力墙的爆裂情况、破坏形态、耐火极限等影响情况；进行单层的高强混凝土剪力墙结构的明火试验和有限元模拟，定量揭示结构中高强混凝土剪力墙的火灾行为；编制高强混凝土剪力墙高温下基于强度破坏的耐火极限计算程序及高温下稳定性能的计算程序，并进行系统的参数分析，建立高温下考虑爆裂影响的高强混凝土剪力墙耐火极限的简化计算方法；进行火灾后高强混凝土剪力墙压弯性能和抗震性能的试验研究和计算分析，提出火灾后高强混凝土剪力墙剩余承载力的实用计算方法。本项目的研究成果可为高强混凝土剪力墙的抗火设计和灾后评估奠定基础。

高强混凝土剪力墙由于高温下混凝土的爆裂和钢筋压屈的影响，可导致其耐火性能和灾后性能较普通混凝土剪力墙降低更多。高温下楼盖等相邻构件的影响可使高强混凝土剪力墙处于面外偏压等较为不利受力状况。目前有关高强混凝土剪力墙耐火性能和灾后性能的研究成果偏少。另外不同受火方式后混凝土柱在低周反复荷载作用下性能、基于外包薄壁钢管加固受火后混凝土梁柱构件的承载性能等也有待进一步研究。为此，本项目从试验、理论分析、数值计算三方面对上述问题进行了较系统的研究，主要研究内容和结果：(1) 开展了10片受火后、5片未受火的高强混凝土剪力墙受压承载性能试验和计算分析，分析了受火方式、受火时间、偏心率和混凝土强度等级等对高强混凝土剪力墙受压承载性能的影响规律；(2) 开展了10片受火后、2片未受火的高强混凝土剪力墙抗震性能试验，分析了受火时间、受火方式、轴压比、高宽比、暗支撑的设置以及混凝土强度等级对受火后高强混凝土剪力墙抗震性能的影响情况；(3) 开展了7片高强混凝土剪力墙在轴压和面外偏压荷载作用下耐火性能试验和计算分析，考察轴压比和面外偏心距的影响；(4) 开展了5片混凝土夹心保温墙在0.15轴压比、单面受火情况下的恒载升温试验及受火后受压承载力试验研究，初步掌握了该类夹心保温的墙耐火特性；(5) 进行了4块带边梁约束的混凝土板耐火性能和灾后承载性能试验研究，考察了边梁是否受火及竖向变形、楼板上方是否覆土等影响；(6) 进行了12个混凝土柱、5个混凝土短柱在不同受火方式后抗震性能试验，考察了受火方式、长细比、水平力加载方向、配箍率等影响；(7) 开展了未受火、火灾后和折线形粘贴CFRP布加固火灾后带正交梁和楼板翼缘的梁柱中节点抗震性能试验研究；(8) 开展了37个外包薄壁钢管加固火灾后混凝土棱柱体轴压性能、12个外包薄壁钢管加固火灾后混凝土柱轴压性能、10个外包薄壁钢管加固受火后混凝土柱偏压性能、14个外包薄壁钢管加固火灾后混凝土柱抗震性能、14个外套薄壁U型钢板加固受火后混凝土梁承载性能的试验研究，建立了外包薄壁钢管约束加固高温后混凝土的应力-应变关系，以及外包薄壁钢管约束加固火灾后混凝土柱的轴压和偏压承载力、外套薄壁U型钢板加固火灾后混凝土梁受弯和受剪承载力的简化计算方法。上述研究成果可为高强混凝土剪力墙的抗火设计、灾后损伤评定，以及火灾后钢筋混凝土梁柱构件的损伤评定和加固设计提供参考。