【作者】 董香军；

【导师】 黄承逵； 丁一宁；

【作者基本信息】 大连理工大学 ， 结构工程， 2006， 博士

【摘要】 近年来，随着大跨度桥梁、隧道以及高层建筑的发展，高性能混凝土(HPC)正得到日益广泛的应用。高性能混凝土具有优良的工作度、较高强度和耐久性，但是它却存在脆性高与防火性能低的缺陷，当其遭受高温或火灾时，极易发生爆裂。掺加各类纤维是提高混凝土韧性的主要手段，其研究也已取得一定的成果，但有关纤维高性能混凝土(FRHPC)高温或火灾性能的研究还不多见。本文结合国家自然科学基金项目：纤维混凝土／喷射混凝土在循环高温作用下的力学性能(50278013)，主要进行了以下几方面的工作： (1)为更好评价钢纤维混凝土的弯曲韧性，并配合我国纤维混凝土技术规程的制定，按照不同国家标准进行了钢纤维混凝土梁的弯曲试验，并依据试验结果，对比了目前国际上应用较为广泛的钢纤维混凝土弯曲韧性标准的优缺点，为我国纤维混凝土技术规程的修订奠定了基础。 (2)工作度、强度以及韧性是纤维高性能混凝土的主要性能指标。在研究纤维高性能混凝土工作度和强度的基础上，参照国际材料与结构联合会标准RILEM，进行了钢纤维、合成纤维以及混杂纤维(钢纤维+合成纤维)高性能混凝土梁的弯曲荷载-挠度全曲线试验。结果表明，纤维、特别是钢纤维可显著提高高性能混凝土的弯曲力学性能，并改善破坏形态。同时，纤维类型和掺量均为影响混凝土工作度、强度、弯曲韧性和断裂能的重要指标。 (3)剩余力学性能是衡量结构材料高温性能优劣的重要标志之一。从材料和受高温温度两大方面研究了高性能混凝土在经历不同高温后抗压强度与弯曲力学性能的变化规律。分析了高温对纤维高性能混凝土梁弯曲破坏形态的影响，利用超声波法研究了混凝土受高温温度与抗压强度之间的关系，基于扫描电镜试验分析了高温后混凝土微观组织结构与力学性能之间的关系。结果表明，高温后混凝土的抗压强度与弯曲性能普遍降低。纤维、特别是钢纤维可有效提高混凝土高温后的剩余力学性能。纤维类型和掺量对高性能混凝土高温后弯曲性能的影响规律与常温下类似。 (4)通过燃烧液化石油气模拟火灾，并对混凝土的膨胀变形进行约束，研究了高性能混凝土在不同受火方式下的爆裂性能。试验证明所采用的加热方式是可行的、有效的。结果表明，钢纤维不但不能抑制混凝土的火灾爆裂，而且随其掺量的增加，爆裂有加剧的趋势；合成纤维对抑制高性能混凝土火灾爆裂具有非常出色的表现，证明了爆裂是缘于蒸汽压机理。更多还原

【Abstract】 Recently, high-performance concrete (HPC) is more and more widely used in construction with the development of long-span bridge, tunnel and high-rise building. HPC has been shown to have a number of advantages such as workability, strength and durability. However, it also suffers from two major weaknesses: higher brittleness and lower fire resistance. HPC has been found to be prone to spalling when subjected to high temperature or fire. The addition of fibers is a main means to improve the toughness of HPC and some progresses have also been made in the study on fiber reinforced concrete (FRC), while the investigations on the high temperature and fire resistance properties of fiber reinforced high-performance concrete (FRHPC) are still limited. Based on the project of National Nature Science Foundation of China - Investigation on bearing capacity of fiber reinforced concrete/shotcrete under the repeated high temperature (No. 50278013), the following aspects are carried out in this thesis:(1) In order to estimate the toughness of FRC and to establish Chinese Guideline of FRC, many experiments of flexural toughness for steel fiber reinforced concrete (SFRC) beams are completed according to different international guidelines. Based on test results, the comparisons of different foreign flexural toughness test methods are carried out. It provides basis for the establishment of guideline of FRC in our country.(2) Workability, strength and toughness are significant properties of FRHPC. Based on the investigations on the workability and strength of FRHPC, flexural experiments of HPC reinforced with steel fibers, polypropylene (PP) fiber and hybrid fibers (steel fiber + PP fiber) are carried out according to RILEM. Experimental results show that fibers, especially steel fibers can obviously improve the flexural properties and failure patterns of HPC. In addition, both fiber type and fiber content play important roles in the workability, strength, flexural toughness and fracture energy of HPC.(3) Residual mechanical properties can be used to estimate the high temperature performance for structural materials. The degenerative rules of compressive strength and flexural properties of HPC subjected to high temperatures are investigated from two aspects of material and high temperature. The effects of high temperatures on the flexural failure patterns of FRHPC are analysed. The relationship of compressive strength and temperature acting on HPC are investigated by ultrasonic. Based on SEM test, the relationship between更多还原