预应力碳纤维板加固混凝土梁的应力损失研究

发布时间：2018-10-10 17:55

【摘要】：碳纤维材料作为一种高性能材料已被大量应用于加固工程。但是试验研究表明，传统的粘贴方法不能发挥碳纤维材料的高强度，并且加固效果很有限。预应力加固技术是一种主动加固技术，不但可以使碳纤维材料的高强度得以发挥，而且可以大幅度提高加固效果。截至目前，国内外出现了多种预应力碳纤维材料加固技术，是当前加固技术的研究热点。利用预应力碳纤维材料加固必然关系到预应力损失的研究。目前对预应力碳纤维材料预应力损失的研究主要针对碳纤维布和碳纤维板的研究，但是查阅文献发现以往研究的碳纤维片材的预应力水平相对于碳纤维材料来说是偏低的（普遍低于1000Mpa），而预应力损失率还是偏高的（10％～30％）。本研究团队开发了铰式锚张拉锚固碳纤维板的预应力工艺，对于以该工艺为基础的预应力损失研究还是存在一些不足，有些研究还是空白。为此，本论文对铰式锚预应力碳纤维板工艺的预应力损失进行了系统的试验研究和理论分析，取得如下主要成果： ①通过对大比例T梁构件的预应力加固试验，测试了单层和双层碳纤维板在预应力张拉过程、预应力放张以及中短期损失等的应力变化，总的预应力损失率都低于3％，，其中单层碳纤维板（50mm×2mm）在高预应力水平（2079MPa）下，预应力损失率1.6％。这些试验结果表明，以铰式波形锚为基础的预应力碳纤维板张拉工艺其工作效率高，应力损失低，技术相对较先进。 ②在本文采用的加固工艺中，紧固螺栓时的扭矩作用和碳纤维板顶升作用都能够少量的增加碳纤维板中的拉应力，弥补其预应力损失，有可能使碳纤维板的最终有效预应力超过首次张拉的碳纤维的应力，这是本文预应力工艺的特点之一。 ③推导出了扭矩作用和顶升碳纤维板时预应力增量的计算公式，为实际工程中这两部分预应力增量的计算提供参考。 ④参照《公路钢筋混凝土及预应力混凝土桥涵设计规范》中后张预应力损失分类及计算方法，总结和推导了以铰式锚张拉碳纤维板的预应力损失的主要因素：锚固系统变形、混凝土的弹性压缩、预应力碳纤维板的应力松弛、混凝土的收缩和徐变，并给出了各项预应力损失的计算公式及有效预应力计算方法。以上研究表明，采用铰式锚张拉碳纤维板的预应力工艺，张拉操作简单，回缩量小，锚固可靠，作业效率高。综合考虑各种因素的影响，混凝土构件的长期损失可以近似的取3%的初始张拉应力为总预应力损失的简化估算值。
[Abstract]:As a kind of high performance material, carbon fiber material has been widely used in reinforcement engineering. However, the experimental results show that the traditional bonding method can not exert the high strength of carbon fiber material, and the reinforcement effect is very limited. Prestressed reinforcement is a kind of active reinforcement technology, which can not only make the high strength of carbon fiber material play, but also greatly improve the effect of reinforcement. Up to now, there are many kinds of prestressed carbon fiber reinforcement technology at home and abroad, which is the research hotspot of current reinforcement technology. The study of prestress loss is bound to be related to the reinforcement of prestressed carbon fiber material. At present, the research on prestressing loss of prestressed carbon fiber material is mainly focused on carbon fiber sheet and carbon fiber sheet. But it is found that the prestress level of carbon fiber sheet is lower than that of carbon fiber material (generally lower than 1000Mpa), and the loss rate of prestress is still high (10% or 30%). The research team has developed the prestressing technology of hinged anchor tension Anchorage carbon fiber slab. There are still some deficiencies in the study of the prestressing loss based on this technology and some researches are still blank. Therefore, in this paper, the prestress loss of hinged anchor prestressed carbon fiber slab is systematically studied and theoretically analyzed. The main results are as follows: 1 through the pre-stressed reinforcement test of large proportion T-beam members, The stress changes of monolayer and bilayer carbon fiber slabs during prestress tensioning, prestressing tensioning and medium and short term losses are measured. The total prestress loss rate of monolayer carbon fiber sheet (50mm 脳 2mm) is lower than that of three layers, in which monolayer carbon fiber sheet (50mm 脳 2mm) is at high prestress level (2079MPa). The loss rate of prestress is 1.6%. These experimental results show that the prestressed carbon fiber sheet tensioning process based on hinged wave anchors has the advantages of high efficiency, low stress loss and relatively advanced technology. 2 in the reinforcement process adopted in this paper, Both the torque and the jacking action of the fastening bolt can increase the tensile stress in the carbon fiber plate and make up for the loss of prestressing force. It is possible that the ultimate effective prestress of the carbon fiber plate exceeds the stress of the first tensioned carbon fiber. This is one of the characteristics of the prestressing technology in this paper. 3. The formulas for calculating the torque and the increment of prestressing force when jacking carbon fiber slabs are derived. It provides a reference for the calculation of the prestress increment of these two parts in practical engineering. (4) with reference to the classification and calculation method of post-tensioned prestress loss in the Design Code for reinforced concrete and Prestressed concrete Bridges and culverts of Highway, This paper summarizes and deduces the main factors of prestressing loss of carbon fiber sheet with hinged anchor: deformation of anchoring system, elastic compression of concrete, stress relaxation of prestressed carbon fiber sheet, shrinkage and creep of concrete. The formulas for calculating the prestress loss and the calculation method for the effective prestress are also given. The above research shows that the prestressing technology of hinged anchor tensioning carbon fiber slab is simple in tensioning operation, small in retraction, reliable in anchoring and high in working efficiency. Considering the influence of various factors, the long-term loss of concrete members can be approximately taken 3% of the initial tensile stress as the simplified estimate of the total prestress loss.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375.1

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