预应力CFRP板加固带缺陷钢梁抗弯性能试验研究

发布时间：2018-10-23 08:51

【摘要】：钢结构在长期服役过程中,不可避免的存在各种损伤或缺陷。碳纤维增强复合材料(Carbon Fiber Reinforced Polymer,简称CFRP)具有高强耐腐、施工方便的特点,利用胶粘剂把CFRP粘贴在钢结构表面以提高其承载力的CFRP加固方法被广泛应用于带损伤钢结构的加固。为加固修复带缺陷钢梁的抗弯能力,通常做法是在其受拉翼缘粘贴CFRP。但这种加固形式往往由于CFRP材料端部缺少必要的锚固措施,造成CFRP过早剥离破坏,CFRP利用率不高,造成极大的材料浪费。采用预应力CFRP对带缺陷钢结构进行加固可以减小结构变形,充分发挥CFRP材料的优越性。本文对带端锚预应力CFRP板加固带缺陷钢梁进行了试验研究,主要的研究内容和结论如下:(1)对带端锚预应力CFRP板加固缺陷梁的预应力损失情况进行研究,利用电阻式应变片以及光纤光栅传感器监测20%和40%预应力水平的CFRP板放张瞬时及放张后中长期预应力损失情况,结果显示:平板锚具能够有效锚固CFRP板,减少预应力损失。放张瞬时,P-20%梁和P-40%梁的预应力损失比例平均值分别为0.91%和0.73%。CFRP板的中长期预应力损失主要发生在放张后的前30天。从CFRP板放张瞬时到放张后102天,P-20%-3梁和P-40%-3梁的预应力总损失比例分别为1.60%和1.43%。(2)对非预应力和预应力CFRP板加固试件进行静载试验研究,对比不同试件的荷载-挠度曲线,荷载-应变曲线,破坏模式等结果发现:带端锚预应力CFRP板加固方式可以更有效抑制带缺陷钢梁的裂纹开展,提高缺陷钢梁的极限承载力、刚度、延性和CFRP板利用率。与带端锚非预应力加固试件相比,20%和40%预应力水平加固试件的极限承载力可分别提高27.5%和52.3%,CFRP板极限利用率可分别提高25.6%和39%。(3)对比不同位置的荷载-应变曲线、不同荷载下的CFRP板应变分布图以及裂纹发展规律和破坏模式,结果显示:带端锚预应力CFRP板加固缺陷梁的破坏始于跨中,这是由于跨中裂纹处应力集中导致胶层开裂,CFRP板剥离。随后剥离破坏向端部扩展,最终CFRP板在接近平板锚处发生断裂。
[Abstract]:In the long service process of steel structure, there are inevitably various kinds of damage or defects. Carbon fiber reinforced composite (Carbon Fiber Reinforced Polymer, (CFRP) has the characteristics of high strength and corrosion resistance and convenient construction. The CFRP strengthening method which uses adhesive to attach CFRP on the surface of steel structure to improve its bearing capacity has been widely used in the strengthening of steel structures with damage. In order to reinforce and repair the flexural capacity of steel beams with defects, CFRP. is usually attached to the flange of the steel beam. However, due to the lack of necessary anchoring measures at the end of CFRP material, the CFRP is destroyed prematurely, and the utilization ratio of CFRP is not high, which results in a great waste of material. Using prestressed CFRP to reinforce the steel structure with defects can reduce the deformation of the structure and give full play to the superiority of the CFRP material. The main contents and conclusions of this paper are as follows: (1) the prestressing loss of prestressed CFRP slab with end anchor is studied. Resistive strain gauges and fiber Bragg grating sensors are used to monitor the transient and long-term prestressing loss of 20% and 40% prestressed CFRP slabs. The results show that the plate Anchorage can anchor CFRP plates effectively and reduce the prestressing loss. The prestressing loss of P-20% beam and P-40% beam is 0.91% and that of 0.73%.CFRP slab mainly occurs 30 days before tensioning. From the instantaneous tensioning of CFRP plate to 102 days after tensioning, the total prestressing loss ratios of P-20-3 beam and P-40-3 beam are 1.60% and 1.43% respectively. (2) the static load test of unprestressed and prestressed CFRP plate reinforced specimens is carried out, and the load-deflection curves of different specimens are compared. The results of load-strain curve and failure mode show that the reinforcement method of prestressed CFRP plate with end anchor can restrain the crack development of steel beam with defects more effectively and improve the ultimate bearing capacity stiffness ductility and utilization ratio of CFRP plate. Compared with unprestressed reinforced specimens with end anchor, the ultimate bearing capacity of 20% and 40% prestressed horizontal strengthened specimens can be increased by 27.5% and 52.3%, respectively, and the limit utilization ratio of CFRP plates with end anchor can be increased by 25.6% and 39.1% respectively. (3) the load-strain curves at different locations are compared. The strain distribution diagram of CFRP slab under different loads, crack development law and failure mode, the results show that the failure of prestressed CFRP plate strengthened with end anchor begins in the middle of span, which is due to stress concentration in the center of span leading to the crack of glue layer and the peeling of CFRP plate. Then the peeling failure extends to the end, and finally the CFRP plate breaks near the plate anchor.
【学位授予单位】：广东工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU391

【参考文献】