【作者】 吕国玉；

【导师】 王小平； 蒋沧如；

【作者基本信息】 武汉理工大学 ， 结构工程， 2003， 硕士

【摘要】 在过去半个多世纪中，预应力混凝土构件在各种结构中都得到了巨大的应用。然而和普通钢筋混凝土一样，预应力混凝土中存在的一个主要问题是钢筋抗腐蚀能力弱，结构耐久性差。这使得大量的预应力混凝土结构需要修理加固，造成了巨大的经济损失。混凝土结构中钢筋的腐蚀问题引起世界上许多学者注意，提出了一些可行的方法。目前一个很有发展前景的方法是用纤维增强塑料筋代替混凝土中的钢筋或预应力钢筋。 纤维增强塑料(fibre reinforced plastics／polymer简称FRP)是以纤维为增强材料，以树脂为基体材料，并掺加辅助剂，经拉拔成型和必要的表面处理所形成的一种新型复合材料。和钢筋相比，具有比强度高、抗腐蚀能力强、抗疲劳性能好、耐电磁等优点，因此在混凝土结构中，用纤维增强塑料筋代替钢筋，可以有效地克服钢筋的腐蚀问题，提高结构的耐久性。 由于纤维增强塑料筋的横向强度较低，传统的钢筋锚具不适用于纤维增强塑料筋的锚固。用纤维增强塑料筋做预应力筋所面临的一个关键问题是开发合适的锚固系统。现有的纤维塑料筋锚具可分为两类：楔紧型锚具和粘结型锚具，性能基本能满足工程需要，但仍存在以下问题：①楔紧型锚具在锚固区对纤维塑料增强筋产生过大的径向应力，导致纤维塑料增强筋的早期失效；②粘结型锚具中，作为粘结材料的树脂会发生徐变，引起预应力损失，锚具的长期稳定性差。总之，现有的纤维增强塑料筋锚具尚不完善，不能满足对锚具组装件的所有技术要求。本文旨在设计适用于碳纤维增强塑料筋的锚具，克服同类锚具的缺点，使锚具在预应力构件的整个使用寿命期间不会影响碳纤维筋的强度。 本文共分七章。第一章和第二章简要介绍了钢筋混凝土所面临的问题、纤维塑料筋的发展历史、生产过程及优点，总结了常用类型的纤维塑料筋在短期荷载和长期荷载作用下的力学性能。第三章对常用的钢筋锚具做了介绍，并初步分析了楔紧型锚具的受力情况。第四章列举了国外现有的纤维增强塑料筋锚具，论述了各种锚具的特点、失效现象和存在的问题。三、四章的内容为碳纤维增强塑料筋锚具的设计提供了借鉴意义和参考依据。在第五章，总结了纤维增强塑料筋锚具的技术要求，提出了减小锚固区应力峰值的两种方法：软化区概念和角度差异概念，并论述了锚具组装件弹性理论分析方法；应用角度差异概念，通过比较不同角度的锚具锚固区的应力分布，设计了不锈钢锚具，在这种锚具中，纤维增强塑料筋的应力分布比较均匀;在钢锚具的基础上，又设计了混凝土锚具，并简要介绍了超高性能混凝土的特性。第六章论述了纤维增强塑料筋与混凝土、砂浆和树脂的粘结机理及影响因素，讨论了粘结应力、纤维增强塑料筋应力及锚固长度的计算方法，设计了用树脂、砂浆分段锚固纤维筋的复合锚固系统，以克服树脂在长期性能方面的不足。第七章论述了纤维增强塑料筋的发展前景，提出了锚具设计中进一步研究的建议。更多还原

【Abstract】 During the past half century ,the use of prestressing members has increased tremendously in a various of structure. However, like general reinforcement concrete structure ,a main problem in prestressed concrete is the poor corrosion resistance of steel tendon which may lead to the lower durability construction . This make a number of prestressed structures need to be strengthened , which cause vast economic losses . Many researcher began to pay attention to steel tendon corrosion and provided some useful measurements .More recently , a effective idea is the way to replacing steel tendon or prestressing strands with the fibre reinforced plastics or polymer in reinforcement concrete.Fibre reinforced plastics (FRP) is composed of fiber filament and a resin matrix. The fiber of high tensile strength and high modulus of elasticity is used as reinforcing material . The synthetic resin is used as matrix material and is mixed with adequate auxiliaries . The fiber reinforced plastic rebar is manufactured using a pultrusion method and necessary surface process . It offers significant advantages over conventional reinforcing , namely , high tensile strength to weight ratio , excellent corrosion resistance , high fatigue strength and electro -magnetic neutrality . As a result , replacing steel bar with FRP in reinforcement concrete may effectively overcome corrosion of steel tendon and increase structural durability.Conventional anchors for steel tendon are inadequate to FRP due to the relative weakness of FRP tendon in the transverse direction . The key problem facing the application of FRP tendons in prestressed concrete is the development of an appropriate anchorage system . At present , two main types of anchors are usually used with FRP tendons : mechanical gripping anchors and bond type anchors . These anchors may essentially satisfy the engineering needs . But there are still some shortcomings in these anchors : 1.Excessive radial pressure on FRP tendon exerted by wedge result in premature failure in anchorage zone . 2.The creep of resin as boned material results hi the losses of prestressing stress and the long -term stability is poor . hi words , available anchors are not perfect and can not satisfy all the technical requirements of a post- tensioning anchorage -tendon assembly . This dissertation try to design adequate anchorage for CFRP to eliminate such defect hi available anchors .This dissertation consists of seven parts . A brief description of the key problem existed in reinforcement concrete , the historical development , the production process and the advantages of FRP tendon is given in Chapter 1 and chapter 2 . The short- term and long- term mechanical properties of the common types of FRP reinforcement are also summarized . In chapter 3 , the common anchors for steel tendon are outlined and the wedge anchor is preliminary analysed . In chapter 4 , some current available anchors for FRP tendon at home and abroad are introduced and the performances , the failure mode and the problem needed to be solved of various anchors are dealt with . In chapter 5 , the technical requirements of FRP anchors are summarized . Two concepts are presented to reduce stress peak in anchorage zone : the soft zone concept and the differential angle concept, and a dedicated numerical method using the theory of elasticity has been developed . Then , using the differential angle concept, a new stainless steel anchorage for CFRP has been developed according to comparing the stress distribution on CFRP in different angle of anchor .There are relative uniform stresses on CFRP tendon in this new anchor. On the basis of steel anchor , a new type of concrete anchor is designed , followed by brief introduction of the properties of ultra -high performance concrete . In chapter 6 , the bond mechanisms and influential factors to FRP and concrete , mortar , resin are discussed . The bond stress, the stress of FRP and embedment length are also dealt with . A complex anchorage system, which may get over the default in long- term perfo更多还原