FRP加固金属结构研究综述

FRP加固金属结构技术是近年来在工程领域中使用越来越广泛的一种加固方法。在国内外对FRP加固金属结构研究的基础上,归纳和总结了FRP与金属材料的粘贴机理,FRP加固金属受拉构件、受压构件、受弯构件及压弯构件的承载力、稳定性、疲劳性能和滞回性能的研究现状,指出了FRP加固金属结构进一步研究的重点,为后续研究提供参考。     

FRP加固钢结构的研究进展

钢结构在设计、制造、施工过程中可能产生各种缺陷,在使用阶段因超载、锈蚀、疲劳等原因会引起损伤累积,从而影响结构的安全。传统的钢结构加固方法主要有钢板焊接、螺栓连接、铆接或者粘接,这些方法存在许多缺点,如产生新的损伤和焊接残余应力等。而纤维增强复合材料(FRP)由于具有比强度和比刚度高、耐腐蚀等特点,已在混凝土结构加固中得到广泛应用。近年来的研究表明,FRP加固钢结构也显示出很好的效果。对国内外FRP加固钢结构的研究现状与进展进行了全面回顾与展望,涉及到钢结构构件的加固试验研究、胶粘剂及其受力分析研究、耐久性研究等诸方面。     

纤维增强复合材料与钢材复合加固混凝土结构研究进展

纤维增强复合材料与钢材复合加固混凝土结构技术,结合了粘贴纤维增强复合材料(FRP)和外贴钢板加固混凝土结构两种技术,可有效改善混凝土结构的受力性能。总结近年来FRP与钢材复合加固混凝土梁、板和柱力学性能以及设计理论的研究进展,分析已有研究取得的成果和尚存的问题。分析表明:FRP与钢材复合加固技术能同时提高被加固构件的延性和承载力,有效解决了FRP加固技术的锚固问题,但关于FRP与钢材复合加固构件的力学性能、设计方法等有待深入研究。应进一步通过试验研究和有限元分析的方法,综合考虑二次受力、加固量等因素对FRP与钢材复合加固混凝土构件受力性能的影响,加固材料的设计取值、加固设计方法和FRP与钢复合材料耐久性研究等是今后关注的课题。     

预应力FRP布加固混凝土梁的承载力计算

预应力FRP布加固混凝土梁可充分发挥材料高强度,又能有效抑制构件裂缝和变形的发展,使其在混凝土结构工程加固领域中得到了广泛的研究和应用。虽然国内外对预应力FRP加固混凝土梁的抗弯、抗剪承载力、预应力损失、弯曲疲劳性能、粘结滑移性能、施工工艺、机具、锚固方式等方面进行了研究,但由于组合结构材料本身受力性能的复杂性,仍然有很多问题没有很好地解决。例如：方便快捷的预应力锚具的开发应用,预应力损失的进一步试验研究,温度应力对预应力损失的影响,截面形状对受弯承载力的影响,预应力纤维布加固混凝土梁的刚度计算等问题。     

FRP片材加固混凝土梁剥离承载力计算及设计

粘贴FRP片材加固混凝土结构的界面剥离是该加固技术的关键问题。根据近年来对FRP片材加固混凝土的界面粘结性能、FRP片材加固混凝土梁的受弯和受剪剥离性能的试验和理论研究,介绍了FRP片材加固混凝土梁的抗弯和抗剪剥离承载力的计算和设计方法,及其有关保证剥离承载力的构造要求。     

FRP片材在混凝土结构加固中的应用

研究了FRP材料的组成及力学特性,分析了FRP加固混凝土的工作原理,通过FRP在混凝土加固工程中的应用,得出FRP复合材料与钢结构相比具有较好的抗腐蚀能力,对混凝土结构进行加固与修复可有效提高工程效率、改善构件受力状况的结论.     

FRP加固钢筋混凝土墩柱抗震性能研究综述

回顾并总结了纤维增强复合材料(FRP)片材和织物抗震加固钢筋混凝土(RC)结构的研究现状,介绍了FRP的加固方式,包括粘贴形式和锚固方法;对影响FRP抗震加固效果的原柱条件、加固参数和受力条件的试验研究现状进行了归纳,探讨了FRP加固墩柱的破坏模式及FRP加固结构的抗震性能理论研究进展.针对现有研究成果,提出了一些FRP加固结构抗震性能研究的建议和意见,为其后续研究提供了参考.     

复合材料FRP在工程结构中的应用

纤维聚合物（Fiber Reinforced Polymer,简称FRP）复合材料由于其质轻、高强、耐腐等特点,已被广泛应用于土木工程中.针对一些工程结构急需维修加固的实际情况,对FRP在桥梁结构、混凝土结构、钢结构以及岩土工程中的应用进行了概述,并对预应力FRP筋或布置在混凝土结构构件的试验研究和应用进行了综述,最后指出了FRP用于工程结构存在的问题及发展前景.     

FRP加固梁柱节点受力性能的影响因素分析

通过对现有FRP加固梁柱节点的研究成果进行总结,对纤维类型、纤维加固方式、纤维粘贴厚度等因素对加固后节点受力性能的影响展开分析,指出各因素对节点受力性能的影响规律。     

一种快速FRP加固钢结构的新技术

介绍一种新的FRP加固钢结构技术.这种技术采用柔性的FRP预浸板(包括两种不同模量的CFRP预浸板和一种GFRP预浸板)和薄膜胶,可以在几个小时之内完成对结构的加固和养护.首先对几种典型的FRP板(由预浸板叠合而成)和薄膜胶进行双盖板搭接节点的拉伸试验,结果表明使用这种新技术可以在FRP板与钢材之间形成良好的界面黏结强度.接着,介绍两种FRP板加固钢梁的受弯性能试验研究,结果同样表明这种加固技术的良好性能.最后,考虑实际情况,还对养护期间的持续振动荷载对加固钢梁抗弯性能的影响进行了研究.研究表明,这种快速FRP加固技术能对钢结构进行快速而有效的加固,具有良好的应用前景.     

纤维增强复合材料对钢结构的加固

在过去的20年中,纤维增强复合材料凭借其高强重比和良好的抗腐蚀性等独特优势,逐渐获得在实际土木工程应用中的广泛认可。特别是对使用纤维增强复合材料在加固混凝土结构方面进行了广泛研究。最近,使用纤维增强复合材料来加固现有的钢结构的方法引起了关注。文章首先对合理开发使用纤维增强复合材料来加固钢结构的方法进行讨论。之后对现有的运用纤维增强复合材料加固的钢结构的研究进行评论和阐述。评论涵盖的论题包括钢材表面粘合剂处理、粘合剂的挑选、纤维增强塑料和钢材之间的粘结性能及其合适的建模、钢梁抗弯加固、钢结构抗疲劳加固、薄壁钢结构的抗局部屈曲的加固、以及通过外部纤维增强塑料对中空管或混凝土填充钢管进行加固。文章最后对未来需进一步研究的问题进行了展望。     

Strengthening of steel structures with fiber-reinforced polymer composites

Over the past two decades, fiber-reinforced polymer (FRP) composites have gradually gained wide acceptance in civil engineering applications due to their unique advantages including their high strength-to-weight ratio and excellent corrosion resistance. In particular, many possibilities of using FRP in the strengthening and construction of concrete structures have been explored. More recently, the use of FRP to strengthen existing steel structures has received much attention. This paper starts with a critical discussion of the use of FRP in the strengthening of steel structures where the advantages of FRP are appropriately exploited. The paper then provides a critical review and interpretation of existing research on FRP-strengthened steel structures. Topics covered by the review include steel surface preparation for adhesive bonding, selection of a suitable adhesive, bond behavior between FRP and steel and its appropriate modeling, flexural strengthening of steel beams, fatigue strengthening of steel structures, strengthening of thin-walled steel structures against local buckling, and strengthening of hollow or concrete-filled steel tubes through external FRP confinement. The paper concludes with comments on future research needs.     

预制夹芯保温墙体FRP连接件应用进展

预制混凝土夹芯保温墙体是集承载与保温一体化的新型预制保温墙体,该墙体由内外层混凝土墙板、中间保温层及连接件等组成。按照材料的不同,连接件主要分为普通钢筋连接件、金属合金连接件和纤维塑料(FRP)连接件三种。FRP连接件具有导热系数低、耐久性好、强度高的特点,可有效降低墙体的传热系数,具有广阔的工程应用前景。本文介绍了预制混凝土夹芯保温墙体FRP连接件分类、国内外研究与应用进展和技术规范情况,并对今后FRP连接件研究工作进行了展望。     

用FRP加固钢结构的研究现状

采用FRP加固钢结构对于现有结构的翻新已成为明智的选择。回顾了在下列领域中为数不多、但发展迅速的一些研究:钢与FRP之间的粘结、钢空心截面的加固、FRP-钢系统中疲劳裂缝的走向。明确了未来的研究方向,如粘结-滑移关系、CFRP加固钢构件的稳定性以及疲劳裂缝发展的模型。     

FRP-混凝土界面的剥离分析

本文简单介绍了FRP及其在土木工程中的应用,重点分析了FRP-混凝土界面的剥离现象,首先回顾了剥离破坏的几种常见类型,接着分析了界面的受力情况和剥离破坏的原因,最后探讨了FRP粘结长度和粘结层厚度对剥离破坏的影响。     

Short and long-term bond performance of prestressed FRP sheet anchorages

This paper discusses experimental results of the short and long-term behavior of the anchorage zones of externally bonded prestressed fiber reinforced polymer (FRP) sheets. An experimental program was conducted to investigate seven beams bonded with prestressed FRP sheets including anchored or unanchored FRP sheet ends. Using different layers of FRP sheet, the prestress level of FRP sheets varied from 20% to 40% of the guaranteed tensile strength. The experimental observation was conducted in an outdoor environment and lasted about twenty months when temperatures were in the 7–30 ^°C range. This study provides significant data on the development of the effective bonding lengths, as well as the initiation and propagation of debonding along the FRP-concrete interface due to creep effect of the adhesive layer. Although adhesive creep leads to debonding propagation at higher shear stress, this creep is favored at low shear stress because it increases the effective bond length which improves the bond capacity of FRP-concrete interface and prevents premature failure of the anchorages. The effective bonding length was found to increase to 50% due to creep of the adhesive layer. The anchored end of the FRP sheets using steel plates and anchor bolts is an effective solution to enhance the bond capacity of FRP-concrete interface for short and long-term loading.     

Strain monitoring of RC members strengthened with smart NSM FRP bars

Fiber-reinforced polymer (FRP) bars can be used as internal reinforcement for new reinforced concrete (RC) structures and as near-surface mounted (NSM) reinforcement for the strengthening of RC structures. The NSM method is an emerging strengthening technique for RC structures, where FRP bars are embedded into grooves cut in the cover of RC members. In both cases, strain monitoring of the FRP bars is desirable either for the investigation of the structural behavior or for the long-term health monitoring of the structure. This paper presents a study in which fiber-optic sensors were embedded into glass FRP (GFRP) bars to produce smart GFRP bars for NSM applications. The manufacturing process of the smart FRP bars is illustrated and their performance in tensile, bond and beam flexural tests is examined to assess the effectiveness of these smart FRP bars for achieving the dual purpose of structural strengthening and strain monitoring. On the basis of the test results, the advantages and limitations of fiber-optic sensors compared to electrical strain gages in the strain monitoring of NSM FRP bars are discussed. The bond and beam test results also confirm the effectiveness of the NSM method for the strengthening of RC structures.     

FRP strengthened aluminium tubular sections subjected to web crippling

This paper presents a test programme on aluminium tubular structural members that have experienced web crippling failure due to localized concentrated loads or reactions. A series of tests was performed on fibre-reinforced polymer (FRP) strengthening of aluminium tubular structural members subjected to End-Two-Flange and Interior-Two-Flange loading conditions. A total of 58 web crippling tests was conducted. The investigation was mainly focused on the effects of different adhesive and FRP for strengthening of aluminium tubular sections against web crippling. The influence of different widths of FRP plate strengthening against web crippling has been also investigated in this study. The test specimens consisted of 6061-T6 heat-treated aluminium alloy square and rectangular hollow sections. Six different adhesives and six different FRPs were considered in this study. The properties of adhesive and FRP have significant influence on the effectiveness of the strengthening. Most of the strengthened specimens were failed by debonding of FRP plates from the aluminium tubes. There are mainly four different failure modes observed in the tests, namely the adhesion, cohesion, combination of adhesion and cohesion, and interlaminar failure of FRP plate. The failure loads, failure modes, and the load-web deformation behaviour of the aluminium sections are presented in this study. It was found that the web crippling capacity of aluminium tubular sections is significantly increased due to FRP strengthening, especially for those sections with large value of web slenderness ratio.     

FRP在工程结构中的应用与发展

FRP(纤维增强复合材料)近年来在混凝土结构加固中得到广泛的应用,并作为一种新型高性能结构材料受到结构工程界的广泛关注,国内外有关研究和工程单位开展了大量的研究和实践应用。本文介绍了结构工程中常用的FRP材料性能和形式,分析了其优点与不足,并介绍了FRP加固结构、FRP配筋和预应力FRP筋混凝土结构、FRP结构与FRP组合结构以及FRP在桥梁结构、大跨空间结构和智能结构中的应用与发展,以期促进我国土建结构工程中对这一新型高性能材料应用和研究工作的开展。     

Derivation of the bond–slip characteristics for FRP plated steel members

In order to understand the behaviour of steel members retrofitted using adhesively bonded fibre reinforced polymer (FRP) plates, the bond–slip characteristics of the adhesive joint between the FRP and steel must first be established. This is important so that debonding does not occur whilst the members are in service. Previously, purely empirical research on establishing the bond–slip characteristics involved strain gauging the length of the FRP plate, which can lead to a major scatter of results as well as underestimating the peak shear stress. The subject of this paper is to describe a technique for quantifying the bond–slip characteristics based on a structural mechanics approach and which does not require strain gauging the plate. Two types of pull tests and a partial-interaction numerical model are used to quantify the major characteristics of the bond–slip and two types of adhesive are used to illustrate the approach.