【作者】 李金章；

【导师】 朱海堂；

【作者基本信息】 郑州大学 ， 水工结构工程， 2012， 硕士

【摘要】 纤维增强塑料(Fiber Reinforced Polymer,简称FRP)筋混凝土结构存在变形、裂缝宽度过大等问题,通过发挥钢纤维高强混凝土强度、韧性优势与FRP筋形成一种新型结构体系可以满足工程结构对耐久性与适用性的要求。本文采用试验研究与理论分析相结合的方法,研究了BFRP筋钢纤维高强混凝土梁的正截面受弯性能,主要研究内容及成果如下：(1)研究了BFRP筋配筋率、钢纤维体积掺量对BFRP筋钢纤维高强混凝土梁开裂荷载和极限荷载的影响,描述了裂缝开展和破坏形态,分析了筋材应力-应变、挠度及裂缝宽度的变化规律。结果表明：钢纤维显著改善了BFRP筋钢纤维高强混凝土梁正常使用极限状态下的使用性能,缓解了构件耐久性与适用性之间的矛盾。(2)BFRP筋钢纤维高强混凝土梁跨中正截面基本符合平截面假定。根据配筋率、钢纤维掺量采用不同的分析模型,分别运用极限理论建立了不同破坏形态的极限受弯承载力计算公式。(3)采纳美国ACI规范计算裂缝宽度的原理,将钢纤维对裂缝宽度的影响简化为对纵筋类型系数的修正,发现少筋梁的Kf系数呈现线性发展趋势,超筋梁成折线形态发展,据此得到的裂缝宽度计算公式与试验结果符合较好。(4)通过修正ACI规范公式中的有效惯性矩,得到与试验值吻合较好的BFRP筋钢纤维高强混凝土受弯构件挠度计算公式。(5)根据构件脆性破坏特征的分析,给出了BFRP筋钢纤维高强混凝土受弯构件的延性定义及评价指标,并通过取得的试验数据验证了计算方法的准确性。更多还原

【Abstract】 Concrete structure reinforced with fiber reinforced polymer (FRP) bars can usually cause a greater deflection and crack width. In order to get perfect durability and serviceability, a new structural system would be formed by use of steel fiber reinforced high strength concrete and FRP bars. Combining with the experimental researches and theoretical analysis, the flexural behavior of BFRP bar-reinforced high-strength concrete beams with steel fibers were studied in this paper, and the main results are as follows:(1) An investigation was performed for the influence of ratio of reinforcement for FRP bars and fraction of steel fiber by volume on the load-bearing capacity of beams. The appearance and development of cracks, also failure mode was described. While, the changing trend of FRP reinforcement stress, deflection, crack width were analyzed. The test results indicate that steel fiber remarkably improved the working performance of BFRP bar-reinforced high-strength concrete beams with steel fibers.(2) Based on the experimental research in this paper and the recent developments at home and abroad, the difference of the over reinforced beams and insufficient reinforced beams in failure mode as well as mechanical behavior were analyzed. It can be seen that plane sections before bending remain plane after bending. Then, the special calculation model of the BFRP bar-reinforced high-strength concrete beams with steel fibers at different reinforcement ratio and fraction of steel fiber were given, and the calculating methods of the ultimate moment capacities were established using the limit equilibrium theory.(3) Considering the favorable effect of steel fiber on restricting crack width of concrete beams, the value of Kf revealed that the linear trend of over reinforced member and the broken line trend of insufficient reinforced member. Thus, The modified formula of maximum crack width based on the ACI code for the BFRP bar-reinforced concrete beam with steel fibers were put forward.(4) The calculating methods for predicting the deflection of the BFRP bar-reinforced high strength concrete beam were proposed by modifying calculation method of the effective moment of inertia for traditional RC flexural members in ACI code.(5) Based on the brittle failure characteristic of the specimens, the definition, evaluation index and calculating mode of ductility of the BFRP bar-reinforced concrete beam with steel fibers were proposed, and the accuracy was also be verified by the experimental data.更多还原