多点锚固预应力CFRP加固混凝土梁疲劳性能模拟分析

发布时间：2018-09-01 17:05

【摘要】：基于波形齿夹具锚的多点锚固预应力CFRP加固技术是一项体外无粘结快速加固技术，该技术能够可靠地实现CFRP材料的锚固与张拉，且施工方便快捷。经过前期大量的静载试验和理论研究，证明了此加固技术的加固效果明显、性能可靠。但是，关于多点锚固预应力CFRP加固梁疲劳性能的研究才刚刚开始，在实验受到周期长、成本高等因素制约的情况下，大量进行疲劳实验受到限制，模拟分析成为一种重要的研究手段。以2根加固梁的疲劳实验为基础，对多点锚固预应力CFRP加固钢筋混凝土梁的疲劳性能进行有限元模拟，，主要研究内容及成果如下： ①采用与实验梁实际材料相对应的多种单元类型、材料本构关系，建立多点锚固预应力CFRP加固钢筋混凝土梁的ANSYS有限元模型，分析了静力荷载作用下构件的开裂荷载、跨中挠度、中和轴高度变化、钢筋应力、CFRP应力、混凝土应变等性能，并通过计算结果与实验结果的比较分析，验证了有限元模型静力分析方法的可靠性。 ②在静力分析的基础上，引入名义应力法，采用ANSYS软件估算多点锚固预应力CFRP加固钢筋混凝土梁的疲劳寿命，所得计算结果与实验实测结果误差较小，验证了多点锚固预应力CFRP加固钢筋混凝土梁疲劳性能模拟分析方法的可靠性。 ③运用经过验证的模拟分析方法，考虑不同CFRP加固量、锚固点数量及间距和CFRP预应力大小等因素的影响，开展多点锚固预应力CFRP加固钢筋混凝土梁的系列模拟分析，得到主要结论如下：1）增大加固量能够大幅度地提高加固梁的极限承载力和疲劳寿命；2）锚固点位置及间距影响疲劳荷载作用下主筋危险破坏点位置；3）在本文研究范围内，预应力能有效提高构件极限承载力。三点锚固加固梁的疲劳寿命，在本文研究范围内随预应力的增大而延长，且幅度较大。四点锚固加固梁的疲劳寿命，在本文研究范围内随中段CFRP预应力的增大而缩短，随边段CFRP预应力的增大而延长，延长或缩短的幅度均较小。
[Abstract]:Multi-point anchoring prestressed CFRP reinforcement based on corrugated tooth fixture anchors is a fast and unbonded external reinforcement technique. This technique can reliably realize the anchoring and tensioning of CFRP materials, and the construction is convenient and fast. After a large number of static load tests and theoretical studies, it is proved that the reinforcement effect of this reinforcement technology is obvious and the performance is reliable. However, the study on fatigue behavior of multi-point anchoring prestressed CFRP beams is just beginning, and a large number of fatigue experiments are limited under the constraints of long period and high cost. Simulation analysis has become an important research method. Based on the fatigue experiments of two strengthened beams, the fatigue behavior of reinforced concrete beams strengthened by multi-point anchoring prestressed CFRP is simulated by finite element method. The main research contents and results are as follows: 1 the ANSYS finite element model of reinforced concrete beams strengthened by multi-point anchoring prestressed CFRP is established by adopting various element types and constitutive relations corresponding to the actual materials of experimental beams. The cracking load, mid-span deflection, height change of the neutral axis, stress of steel bar CFRP, strain of concrete and so on are analyzed under static load, and the results are compared with the experimental results. The reliability of the static analysis method of finite element model is verified. 2 on the basis of static analysis, the fatigue life of reinforced concrete beams strengthened by multi-point anchoring prestressed CFRP is estimated by introducing the nominal stress method and using ANSYS software. The error between the calculated results and the experimental results is small, which verifies the reliability of the simulation analysis method for the fatigue behavior of reinforced concrete beams strengthened with multi-point anchoring prestressed CFRP. Considering the influence of different CFRP reinforcement amount, the number and spacing of anchoring points and the size of CFRP prestress, a series of simulation analysis of reinforced concrete beams strengthened with multi-point anchoring prestressed CFRP is carried out. The main conclusions are as follows: (1) the ultimate bearing capacity and fatigue life of the strengthened beam can be greatly improved by increasing the reinforcement amount. 2) the location of the dangerous failure point of the main reinforcement affected by the location and spacing of anchoring points under fatigue load is 3) within the scope of this paper. Prestress can effectively improve the ultimate bearing capacity of members. The fatigue life of three-point Anchorage strengthened beam is prolonged with the increase of prestress in this paper. The fatigue life of four-point Anchorage strengthened beam is shortened with the increase of CFRP prestress in the middle section and the increase of CFRP prestress in the side segment in this paper. The extension or shortening range of the fatigue life of four-point Anchorage beam is smaller.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU37

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