FRP加固局部损伤钢压杆的稳定分析

钢结构中存在大量的轴心受力构件,作为承受永久竖向荷载的主要构件,往往是结构加固的重点.采用能量方法,分析各种杆端约束条件下,纤维增强复合材料（FRP）加固局部损伤的轴心受压钢构件在弹性失稳时的弹性屈曲临界力,并建立普遍适用的近似欧拉公式.利用ANSYS通用有限元分析软件分析FRP的厚度对损伤空心圆管临界力的影响并与该公式解析解进行对比.计算结果表明,该公式计算结果可靠,采用纤维增强复合材料加固修复局部损伤的钢结构可以有效恢复其刚度和稳定性.     

碳纤维布加固钢结构有效粘结长度的试验研究

由于腐蚀、疲劳和机械损伤,在役的钢结构中存在不同程度的缺陷和损伤.为了弥补传统钢结构加固方法的缺点,寻求高效的钢结构加固方法迫在眉睫.纤维增强复合材料(FRP)具有优异的性能,在钢结构的损伤部位粘贴FRP具有很多优势.但是到目前国内外(尤其是国内)对粘贴FRP加固损伤钢结构技术的研究和应用涉足甚少.本文对粘贴碳纤维布加固损伤钢结构的受力性能进行了研究,并对碳纤维布与钢结构之间的粘结应力分布规律进行了测量和分析,最后得出了碳纤维布加固钢结构时的有效粘结长度.     

FRP-混凝土界面模型及其应用

纤维增强复合材料FRP(Fiber Reinforced Polymer)已广泛应用于混凝土及其它结构的加固。从上世纪90年代初到现在,这项技术主要应用于结构抵抗静载、疲劳荷载和地震荷载的加固中,最新的研究开始涉及用外贴FRP加固技术增强结构抵抗爆炸和冲击荷载的能力。FRP与混凝土粘结界面是FRP加固混凝土结构中的薄弱环节。由FRP混凝土界面的粘结强度所决定的FRP有效应力是评价不同荷载条件下FRP加固效果的关键指标。本文对目前已有静/动态荷载条件下的FRP混凝土界面模型及其在数值分析中的应用进行了分类和总结。     

碳纤维增强复合材料(CFRP)加固修复损伤钢结构

与传统的钢结构修复方法相比 ,CFRP加固修复钢结构具有明显的优越性 ,是一种先进的钢结构修复方法。总结了国内外对纤维增强复合材料 (FRP)粘结修复钢结构的研究状况 ,并对CFRP加固修复钢结构技术的施工工艺进行了介绍。     

不同FRP增强混凝土梁断裂性能试验研究

为了探讨不同种类纤维增强复合材料（FRP）增强带裂缝混凝土的断裂性能,开展了芳纶纤维增强复合材料（AFRP）、碳纤维增强复合材料（CFRP）和玻璃纤维增强复合材料（GFRP）增强带裂缝混凝土梁的三点弯曲试验,分析了其断裂性能参数.结果表明：相对于普通混凝土梁试件,FRP对带裂缝混凝土梁的阻裂加固效果更明显;CFRP增强混凝土梁的起裂荷载和失稳荷载均大于AFRP与GFRP增强混凝土梁,CFRP的阻裂增强效果最佳;AFRP增强混凝土梁和CFRP增强混凝土梁的破坏形式均为试件底部混凝土 FRP界面的剥离破坏,GFRP增强混凝土梁的破坏形式为试件底部GFRP的拉断破坏;通过对不同FRP增强混凝土梁阻裂加固机理的分析,计算得出CFRP增强混凝土梁的起裂韧度和失稳韧度最大,且CFRP价格适中,因此使用CFRP对带裂缝混凝土梁进行增强加固的性价比最优.     

FRP加固钢筋混凝土梁耐冲击性能相关问题的研究进展

基于静态荷载作用下的纤维增强复合材料(Fiber reinforced polymer,FRP)加固钢筋混凝土梁式构件性能的研究已经开展得相当广泛。相反,冲击荷载作用下FRP对RC梁式构件的加固效果的认识急需提高。冲击荷载作用下RC构件性能的分析需要考虑多种动力学效应,如惯性效应、应变率效应。本文介绍了考虑应变率效应的FRP-混凝土界面动态行为方向的研究现状和冲击荷载作用下的FRP加固钢筋混凝土梁式构件的研究进展,并对值得进一步深入研究的问题进行了探讨与展望。     

FRP加固钢梁的分析

纤维增强复合材料（以下简称FRP）是当今加固工程研究热点之一,混合纤维材料（以下简称HFRP）和碳纤维材料（以下简称CFRP）加固修复混凝土结构已广泛应用于实际工程,相应理论与试验也较完善。国内外用CFRP和GFRP加固钢结构的试验研究较少。本文以GFRP和CFRP加固无损钢梁试验为基础,研究粘结不同种FRP情况下钢梁的荷载一位移曲线和承载力,以此确定粘贴GFRP和CFRP是否能有效地改善钢梁的受力性能。最后对工程加固钢梁提出参考。     

资料索引

浸渍树脂快速与自然老化试验对应关系以纤维增强复合材料(FRP)来加固土木结构被应用于土木工程领域,对混凝土结构、砌体结构、钢结构及木结构进行加固修复。但随着FRP加固结构的广泛应用,其耐久性问题也日益突出并受到关注。FRP加固修复后的结构在使用过程中,除了承受使用荷载的作用外,还要受到各种环境因素的作用,如温度和湿度变化以及化学介质腐蚀等,这些环境因素一方面会影响材料本身的物理力学性能,另一方面会影响FRP材料与结构的界面粘结性能。故研究环境因素对FRP材料物理力学性能和粘结强度的影响具有重要意义。浸渍树脂作为复…     

FRP加固技术在木结构中的研究现状

纤维增强复合材料具有轻质高强、成本低廉、安装快速等优点,将纤维增强复合材料用于木构件的加固及修复可改善并弥补木材的缺陷。FRP加固技术在木结构中的应用研究逐渐成为主流,总结分析近年来国内外学者对FRP加固技术在木结构中的研究现状。     

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 ferritic stainless steel tubular structural members using FRP subjected to Two-Flange-Loading

Cold-formed stainless steel tubular structural members which may experience web crippling failure due to localise concentrated loads or reactions are investigated. A series of tests on fibre-reinforced polymer (FRP) strengthening of cold-formed stainless steel tubular structural members subjected to End-Two-Flange and Interior-Two-Flange loading conditions is presented. The strengthening only applied to a localise area of the members under concentrated load. A total of 58 web crippling tests were conducted. The investigation mainly focused on the effects of different surface treatment, different adhesive, and FRP for strengthening of stainless steel tubular sections against web crippling. The behaviour of stainless steel members strengthened by different widths of FRP plate against web crippling has been also investigated in this study. The test specimens consisted of ferritic stainless steel EN 1.4003 square and rectangular hollow sections. Two different surface treatments were considered. Furthermore, six different adhesives and six different FRPs were also considered in this study. The properties of adhesive and FRP as well as the bonding between the FRP and stainless steel tube have significant influence on the effectiveness of the strengthening. Most of the strengthened specimens were failed by debonding of FRP plates form the stainless steel tubes. Six different failure modes were observed in the tests, namely the adhesion, cohesion, combination of adhesion and cohesion, interlaminar failure of FRP plate, FRP delaminating failure and web crippling failure. The failure loads, failure modes, and the load-web deformation behaviour of the ferritic stainless steel sections are presented in this study. It was found that the web crippling capacity of ferritic stainless steel tubular sections may increase up to 51% using FRP strengthening.     

纤维增强复合材料加固钢结构用黏结剂疲劳性能试验研究

设计了40组试件,分别对20,30,50,60,70℃五种不同养护温度和0.8ΔF、1.0ΔF、1.2ΔF三种不同荷载幅下,两种FRP加固钢结构用黏结剂的疲劳性能进行试验研究,通过对两种不同黏结剂在不同养护温度和不同应力幅下的疲劳性能对比,分析养护温度和荷载幅对黏结剂疲劳循环寿命的影响程度,得到较为适宜的养护温度范围为30~50℃,对工程实践具有实际指导意义。     

Testing and modeling of shear and peel behavior for bonded steel/FRP connections

This paper presents a technique used to evaluate the shear and peel stiffness of an adhesive system that bonds fiber reinforced plastic (FRP) and steel sections. The technique combines experimental results and analytical solutions and involves the simulation of the shear and peel behavior of the adhesive through two continuous spring systems. The experiments involve shear lap testing of FRP sheets bonded to hollow steel sections. A closed form analytical solution was derived for both the in-plane and out-of-plane behavior of the tested FRP sheets. The measured in-plane load-displacement relations were incorporated into the closed form solution to evaluate the spring constant simulating the shear behavior of the adhesive. The out-of-plane behavior of the FRP sheets was identified experimentally through outer face strain and out-of-plane displacement measurements. A curve fitting approach in which the closed form analytical solution was fitted to the measured out-of-plane displacement profile was then used to evaluate the spring constant simulating the peel behavior of the adhesive. The study focused on a methacrylate adhesive system since preliminary investigation has shown it is suitable for applications involving bonding plastic and metal surfaces. The spring constants evaluated in this study can be used to perform detailed modeling of a bonded FRP/steel connection under a general state of loading.     

FRP加固钢板界面应力的有限元分析

对FRP加固钢板的界面应力进行了有限元分析,并对胶层弹性模量、FRP厚度以及组合胶层进行了参数研究,结果表明:FRP端部存在应力集中,剪应力和正应力随胶层弹性模量、FRP厚度的增大而变大,采用组合胶层可以改善端部受力状态。     

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.     

利用砂浆填充FRP管对受压钢构件进行加固

介绍提高受压钢构件抗弯性能的加固方法,砂浆填充FRP管套在钢构件外侧,管端采用FRP织物包裹。对18个双向轴对称截面试件进行三轴压缩试验,得到试件的荷载-应变曲线和失效模式,证实其承载能力和延性得到了提高。对试件钢骨截面、长细比及端部包裹FRP织物层的影响进行了研究。结果表明,加固后,失效模式从由于整体屈曲引起的钢构件中部屈服转变为钢构件端部的局部损伤;因此,试件的承载能力提高了44%～215%,延性增加高达877%。细分模型用于加固构件的计算,由此计算出的承载能力与试验结果相符。     

螺栓连接或粘结成型的CFRP/GFRP复合板钢拼接板双塔式螺栓节点结构性能

给出了螺栓连接或粘结成型的CFRP/GFRP复合板钢拼接板双塔式螺栓节点结构性能相关的试验和数值分析结果。试验共采用了45个双塔式混合连接拉伸试样和6个中跨截面带与不带对接接头的大尺寸抗弯梁试样。对螺栓连接和混合连接(粘结和螺栓连接)两种双塔式螺栓节点进行了研究。结果显示不锈钢、粘合剂和V型缺口拼接板共同组成的双塔式螺栓节点是CFRP/GFRP复合板的有效连接方法。V型缺口拼接板的粗糙表面和粘合剂有助于提高节点刚度。采用数值分析方法获得混合连接的荷载-位移曲线,其结果与试验结果相一致。提出了实际节点设计中的设计新理念。     

HB FRP加固混凝土结构组合界面黏结特性

为揭示HB-FRP(hybrid bonded fiber reinforced polymer)加固混凝土结构多作用组合工作机制,设计了5组黏结作用组合试验.基于实测荷载-滑移关系、应变分布、黏结-滑移关系开展了界面黏结特性研究,提出组合界面黏结-滑移统一模型和黏结荷载表达式.结果表明:HB-FRP加固混凝土组合作用可拆分为FRP黏结混凝土、侧压力和FRP黏结钢板;组合界面的黏结应力发展不同步,FRP板下表面与混凝土的剥离早于FRP板上表面与钢板的剥离,叠合工作时序不同;由侧压力引起的界面摩擦应力随界面应力的发展而增加并趋于稳定;理论模型结果与试验结果具有较好的一致性,可用于计算组合界面的黏结荷载.