分段部分粘结预应力碳纤维板加固混凝土梁的试验研究

发布时间：2018-04-12 18:24

本文选题：波形锚 + 预应力加固　；参考：《重庆交通大学》2015年硕士论文

【摘要】：碳纤维复合材料具有轻质高强、耐酸碱腐蚀、耐久性好等特点,在建筑结构、桥梁结构的加固与修复工程中获得了越来越广泛的推广。近年来,众多的高校和科研单位对预应力碳纤维加固技术的探讨与研究也越来越多,成为当前国内外加固领域的热点。预应力碳纤维板加固的效果依赖两方面,一方面依靠可靠的端部锚固,另一方面,依赖碳纤维板与被加固结构的良好粘结。然而在工程实践中,由于粘结面未能处理好(如碳化层未清理干净等),或者由于粘结胶的耐久性不足,粘结能力退化甚至丧失,等等各种原因,造成预应力碳纤维板有可能存在局部或全部无粘结的情况。对于全部无粘结的情况,工程人员完全可以按照无粘结预应力体系那样进行评估。但对于局部无粘结的情况,可能情况要复杂得多,而这方面的研究目前尚属空白。为此,本研究团队通过对碳纤维板局部涂抹碳板胶,形成了分段部分无粘结预应力碳纤维板加固体系,在有可靠锚固措施的情况下,进行加固混凝土受弯构件的试验研究,得到如下主要结论:①在跨中纯弯区有粘结、剪弯区无粘结的情况下,加固梁最终的破坏形态为剪跨段裂缝过宽,剪跨段的抗弯承载力不足(梁顶混凝土有压溃的趋势)。这一现象表明在弯矩较小的区域无粘结(弯矩较大的区域有粘结),梁的最终破坏区域完全可能发生改变。该现象也从一定程度上说明,由于无粘结的原因,碳纤维板不能充分参与结构的抗弯,其加固效果将显著降低。②在跨中纯弯区无粘结、剪弯区有粘结的情况下,加固梁最终的破坏形态为梁顶混凝土压溃,无粘结区的碳纤维板与梁内的有粘结钢筋应变发展不同步,裂缝发展也不同全粘结的加固梁,表明碳纤维板无粘结的部分不能与原结构共同协调受力。③数据分析表明,无粘结区的碳纤维板与梁内的有粘结钢筋应变发展不同步,裂缝发展也不同全粘结的加固梁,表明碳纤维板无粘结的部分不能与原结构共同协调受力,无粘结区段的预应力碳纤维板的受力与无粘结预应力体系的受力行为有一定程度的相似。以上研究成果进一步证明了良好的粘结界面处理有助于提高预应力碳纤维板加固技术的加固效果,这一点具有很好的工程实用价值。
[Abstract]:Carbon fiber composites (CFRP) have been widely used in the reinforcement and repair of building structures and bridge structures because of their high strength, acid and alkali resistance, durability and so on.In recent years, many universities and scientific research institutions have more and more research on prestressed carbon fiber reinforcement technology, which has become a hot spot in the field of reinforcement at home and abroad.The strengthening effect of prestressed carbon fiber sheet depends on two aspects. On the one hand, it depends on reliable end anchoring, on the other hand, it depends on the good bond between carbon fiber sheet and strengthened structure.However, in engineering practice, due to the failure to deal with the bonding surface (such as the failure to clean the carbonized layer, etc.), or because the durability of the adhesive is insufficient, the bond capacity is degraded or even lost, and so on.It is possible that the prestressed carbon fiber sheet is partially or completely unbonded.For all unbonded cases, engineers can be evaluated as unbonded prestressed systems.However, in the case of local unbonding, the situation may be much more complicated, and the research on this aspect is still blank.For this reason, the research team formed a segmented partial unbonded prestressed carbon fiber plate reinforcement system by applying carbon plate glue to the carbon fiber sheet, and carried out the experimental research on strengthening concrete flexural members under the condition of reliable anchoring measures.The main conclusions are as follows: 1 the ultimate failure mode of strengthened beam is that the crack of shear span section is too wide and the flexural bearing capacity of shear span section is insufficient when there is bond in pure bending zone of span and no bond in shear bending zone.This phenomenon indicates that there is no bond in the region with small bending moment (there is bond in the area with larger moment) and the ultimate failure zone of the beam is likely to change.To some extent, the phenomenon also shows that the carbon fiber sheet can not participate in the bending of the structure fully due to the reason of non-bonding, and the reinforcement effect will be significantly reduced by .2 in the case of non-bonding in the pure bending area of span and in the shear bending zone.The ultimate failure mode of the strengthened beam is that the concrete at the top of the beam collapses, the strain of the carbon fiber plate in the unbonded zone does not develop synchronously with the strain of the bonded steel bar in the beam, and the crack development is different from that of the fully bonded strengthened beam.The results show that the unbonded part of the carbon fiber plate can not coordinate with the original structure. 3 data analysis shows that the strain development of the carbon fiber sheet in the unbonded zone is out of step with that of the bonded steel bar in the beam, and the crack development is different from that of the fully bonded strengthened beam.The results show that the unbonded part of CFRP can not be combined with the original structure, and the behavior of prestressed CFRP in unbonded zone is similar to that of unbonded prestressed system to some extent.The above research results further prove that good bond interface treatment is helpful to improve the strengthening effect of prestressed carbon fiber slab strengthening technology, which has good engineering practical value.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.72

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