碳纤维布加固震后严重损伤混凝土框架的抗震试验研究

以某两层钢筋混凝土工业建筑框架结构为原型,按1∶3的缩尺模型设计了钢筋混凝土框架模型(KJ-1),并对其进行模拟地震作用的水平低周反复荷载作用下的试验;然后对该严重损伤的框架进行碳纤维布加固,对加固后的试件(KJ-1A)再进行同样的试验。对加固前后框架结构的受力性能、裂缝发展、破坏形态、滞回曲线、骨架曲线、位移延性等进行对比分析,研究用碳纤维布加固已严重损伤的混凝土框架结构的抗震性能。试验结果表明,震后严重损伤的混凝土框架结构经碳纤维布加固,其极限承载能力、耗能能力及延性等抗震性能有明显提高,为采用碳纤维布加固补强大震后损伤严重的混凝土结构提供了理论依据。     

碳纤维布加固钢筋混凝土柱滞回耗能分析及目标延性系数确定

对 6根碳纤维布加固混凝土柱进行了反复荷载作用下抗震性能的试验研究 ,分析了其延性系数和滞回耗能性能。研究结果表明 ,采用碳纤维布加固可以提高柱的变形能力和滞回耗能能力 ,使混凝土柱的抗震性能得到显著改善。基于能量准则 ,确定了碳纤维布加固混凝土柱后的目标延性系数。     

碳纤维布增强植筋加层框架抗震性能试验研究

基于一榀钢结构植筋加层框架和一榀碳纤维布节点加固的植筋加层框架的1/3缩尺模型进行低周反复荷载试验,对采用无机锚固材料植筋加层后框架的破坏形态、滞回曲线、刚度退化、位移延性和耗能能力等抗震特性进行研究。试验结果表明:高强早强水泥基无机锚固材料在植筋结构上可以很好地满足工程对其力学性能的要求;使用无机锚固材料植筋技术,对既有混凝土框架结构进行钢结构加层后,结构整体抗震性能较好;使用碳纤维布材料对植筋节点进行加固后,加层框架的破坏机制由混合铰破坏转为梁铰破坏,结构的延性、耗能能力等抗震性能的提高较为明显。     

碳纤维布与钢板复合加固RC梁抗震性能试验

碳纤维布或钢板加固混凝土构件在改善结构抗震性能上均存在不足,二者复合加固具有互补性。基于此,对6根钢筋混凝土梁(5根梁加固)在低周反复荷载作用下的抗震性能进行对比试验,对其破坏特征、滞回曲线、位移延性系数、骨架曲线、刚度退化、承载能力进行对比分析。试验结果表明:复合加固更有效地提高梁的承载力、延性和变形能力,减缓刚度退化,改善钢筋混凝土梁的抗震性能,碳纤维布与钢板能较好地协同工作。     

碳纤维加固单层双跨混凝土框架结构抗震性能试验研究

为了研究碳纤维(CFRP)加固混凝土框架的抗震性能,设计了两榀单层两跨框架结构,其中一榀未加固,另一榀采用碳纤维加固结构柱端。对两结构进行了抗震加载试验,分析并对比了两结构的破坏特点、承载能力等抗震性能。结果表明:碳纤维加固能够明显提高结构的承载能力、变形能力和耗能能力,并能够使结构由"强梁弱柱"型的破坏机制转变为"强柱弱梁"型的破坏机制。     

碳纤维布加固混凝土框架抗震性能试验研究

通过2榀1∶2 52层2跨混凝土框架低周反复加载试验,对应用碳纤维布加固混凝土框架方法进行了探索性研究,从滞回性能、节点核心区剪切变形、耗能能力以及强度、刚度退化等多个方面对加固后框架结构抗震性能的改善效果进行了分析评价。     

增大截面法加固钢筋混凝土框架的抗震性能研究

为研究钢筋混凝土框架采用增大截面法加固后的抗震性能,采用有限元软件ANSYS建立4榀3层4跨钢筋混凝土框架模型,其中1榀为原型对比框架,其他3榀采用增大截面法分别加固1层、2层和3层全部框架柱,在有限元分析软件中对框架模型进行低周反复破坏分析,对比出加固前后结构的承载能力,变形能力,以及抵抗地震力的能力,分析建筑结构加固后性能。研究结果表明,不同加固量下的混凝土框架均有较好的滞回耗能性能和塑性变形能力以及延性,加固越多承载力提高越大,延性并没有受到影响,增大截面发加固混凝土框架柱是较为有效且实用的加固方法。     

系锚碳纤维布间接加固混凝土框架节点抗震性能有限元分析

系锚碳纤维布(简称CFRP)间接加固混凝土框架节点方法能够有效避免直接粘贴加固CFRP易剥离、难以在实际工程中实施等缺陷。通过对5个系锚CFRP间接加固节点在滞回曲线、节点承载力和延性系数等方面的有限元数值模拟对比分析,探讨节点梁端箍筋配箍率、纵向CFRP条带用量及横向CFRP条箍用量等参数对节点抗震性能的影响。分析结果表明:梁柱端间接加固的系锚CFRP能明显改善节点的抗震性能,其极限承载能力和梁端位移延性系数提高幅度分别达到19.8%和55.5%;在其他参数相同的情况下,增加梁端纵向CFRP条带的配置率能同时提高加固节点的抗震延性和承载能力,梁端箍筋配箍率能显著改善其抗震延性,梁柱端横向CFRP条箍配置率对加固节点的抗震延性和承载能力的提高作用不大,但能有效延缓纵筋的屈服和黏结滑移。     

扇形铅黏弹性阻尼器加固RC框架的抗震性能试验研究

针对钢筋混凝土框架结构梁柱节点震害严重的抗震问题,提出采用扇形铅黏弹性阻尼器加固框架结构的 方法,结合扇形阻尼器型式提出外包箱形钢板和外包U形钢板两种不同的加固连接方式。为研究扇形铅黏弹性阻 尼器加固框架的抗震性能,设计并制作了3榀框架试件,分别为空框架和两榀不同连接的扇形铅黏弹性阻尼器加 固框架,通过低周反复加载试验分析了其滞回性能、承载能力、刚度退化、耗能能力等参数。试验结果表明：采 用扇形铅黏弹性阻尼器加固的框架滞回曲线饱满、耗能能力强、加固效果良好;扇形铅黏弹性阻尼器为框架提供 了一定的抗侧刚度,提高了框架的水平承载能力,延缓了框架塑性铰的产生,使框架具有良好的耗能能力;外包 U形钢板和外包箱形钢板用于扇形铅黏弹性阻尼器与主体结构的连接都是有效的,这两种不同的连接方式对加固 框架的整体抗震性能影响不大。     

碳纤维布加固混凝土框架外节点抗震性能试验研究

以碳纤维布对被加固构件混凝土的良好约束性能为纽带,结合多种加固补强材料,提出3种基于碳纤维布的抗震加固混凝土框架节点方法;并通过6个混凝土框架外节点试件的低周反复加载试验,从破坏模式、滞回特性、核心区剪切变形、强度与刚度退化以及耗能能力等方面,分析研究不同加固方法对节点抗震性能的改善效果。     

Full-scale fire experiments on load-bearing cold-formed steel walls lined with different panels

Cold-formed steel (CFS) wall systems were increasingly used as primary load-bearing structural components in residential and industrial buildings. Previous studies were mainly to investigate the fire performance of non-load bearing CFS wall systems lined with gypsum plasterboards. In order to improve the fire performance of load-bearing CFS wall systems more efficiently, this paper presented a detailed experimental investigation on five full-scale CFS walls lined with double layers of three different fire resistant panels on both sides, including fire-resistant gypsum plasterboard, bolivian magnesium board and calcium silicate board. The results showed a noticeable disadvantage of the calcium silicate board due to explosive spalling at high temperatures, and this might cause severe safety issues in an actual fire situation. For CFS walls lined with gypsum plasterboard as the face layer and bolivian magnesium board as the base layer on both sides, different load ratios may result in different failure modes, and the fire resistance time would be more than 90 min when the load ratio was less than 0.65. It was also demonstrated that the fire performance of bolivian magnesium board was superior to that of the fire resistant gypsum plasterboard, therefore the former may be recommended to be used in CFS structures to replace gypsum plasterboards as the base layer.     

夹芯墙板覆面冷弯薄壁型钢承重复合墙体受剪试验

为满足多层冷弯薄壁型钢房屋建筑的抗震及防火要求,同时兼顾施工便捷性,提出了夹心墙板覆面的新型冷弯薄壁型钢复合墙体,并完成了11片足尺模型水平加载试验。试验表明： 1） 复合墙体的受剪破坏主要由墙板周边的螺钉连接失效引起,即螺钉将墙板撕裂或螺钉剪断引起,墙板与自攻螺钉之间的连接力学性能成为影响复合墙体受剪性能的主要因素;增大墙板厚度或者采用玻镁板代替石膏板可提高复合墙体抗剪性能,而龙骨立柱的截面尺寸对复合墙体受剪性能影响不明显; 2） 同侧墙板层数的增加对复合墙体受剪承载力及刚度虽有明显提高,但未达到线性叠加程度;夹心墙板的使用有利于墙体蒙皮效应的发挥,相应的墙体受剪性能优于墙体同侧双层墙板覆面时的受剪性能; 3） 蒸压加气混凝土（ALC）板周边与自攻螺钉的连接区域在较低水平荷载作用下出现板材开裂现象,故不宜采取ALC板参与墙体受力的连接方式。研究给出了新型冷弯薄壁型钢复合墙体的受剪承载力及抗剪刚度设计指标,供工程设计参考。     

单调水平荷载下冷弯型钢墙板性能

对一个定向刨花板覆面的冷弯型钢墙板所做试验研究的调查结果进行介绍。静态横向荷载试验在13个全尺寸的墙板样本上进行,通过使用土耳其所采用的施工细节来调查冷弯型钢墙的性能。试验结果显示,在冷弯型钢墙板的底部使用一定几何形状的连接件来转移拉力,可很大程度地影响墙板的整体性能。试验发现,在连接件和与其相邻的底部发生了大范围的破坏,从而阻止了主要的承载机制引发的墙体刚度。其他所观察的变形模式还包括用螺钉连接的定向刨花面板覆面与冷弯型钢墙板的边界的框架构件的倾斜,以及覆面与框架构件的分离。冷弯型钢框架内斜压杆的存在会引起墙板荷载能力和初始刚度的少量增长。这也证实了使用已有文献中的设计公式可较为精确地预测所测量的墙板的承载能力。     

Multi-criteria analysis for the integrated performance assessment of complex fenestration systems

Complex fenestration systems (CFS) designed to collect and redirect daylight from the sky-vault are generally placed on the upper part of a window in order to improve the distribution of indoor daylight. Due to their additional function as solar protection, their use might contribute to the mitigation of the unfavourable effects that the admission of daylight signifies, especially in buildings located in prevailing sunny climates (risk of glare and overheating). An appropriate selection of the CFS that better contributes to improve the interior daylight environment would imply an integrated performance assessment taking into account relevant aspects such as indoor daylight distribution and the visual and thermal comfort of occupants. However, such an assessment implies the use of performance criteria with different targets; therefore, in order to evaluate their overall performance, a multi-criteria analysis is applied in this study. The method presented here describes a comprehensive evaluation to determine those CFS that better contribute to an improved indoor daylighting environment in a building located in a prevailing sunny climate. The CFS performance assessment was undertaken with computer simulations using their bi-directional transmission distribution function (BTDF).     

碳纤维布粘贴加固BFRP筋-ECC-混凝土组合梁受弯性能研究

工程结构服役期间经常由于使用功能改变或使用荷载增加而需要对结构进行加固改造。为研究经碳纤维布粘贴加固后的玄武岩纤维增强塑料（BFRP）筋-工程用水泥基复合材料（ECC）-混凝土组合梁的受弯性能,对3组共12根不同ECC高度替换率（0、0.29和0.58）的BFRP筋-ECC-混凝土组合梁底分别粘贴1、2和3层碳纤维布的加固构件及未加固构件进行静力受弯性能试验。研究碳纤维布粘贴层数和ECC高度替换率对组合梁受弯承载力和破坏形态的影响。试验结果表明：采用受拉性能优异的ECC替代受拉区部分混凝土形成的ECC-混凝土组合梁不仅可提高构件承载力,还可有效改善构件抵抗开裂和变形的能力;组合梁底粘贴3层碳纤维布,裂缝宽度可降至未加固试件的10%,受弯承载力提高20%,挠度降低50%。借鉴钢筋混凝土理论,基于合理的基本假定和简化的材料本构模型,提出粘贴碳纤维布加固的组合梁受弯承载力计算式,并给出碳纤维布强度折减系数,理论预测值与试验实测值吻合良好。     

采用地聚物粘贴碳纤维布加固混凝土梁试验研究

采用地聚物替代环氧类胶粘剂对混凝土梁进行碳纤维布加固。首先通过地聚物的拉伸剪切试验和粘贴碳纤维布的水泥砂浆试块的双剪试验,比较了不同温度下地聚物和环氧类胶粘剂的拉伸剪切强度和粘结性能;随后开展了4根碳纤维布加固混凝土梁和1根未加固混凝土梁的常温对比试验,验证了采用地聚物粘贴碳纤维布加固混凝土梁的有效性。研究结果表明：地聚物的耐高温性能明显优于环氧类胶粘剂;常温下采用地聚物粘贴单层碳纤维布加固混凝土梁的承载能力与采用环氧类胶粘剂时相差不大。     

Thermal performance modelling of complex fenestration systems

Complex fenestration systems (CFS) have become standard elements in facade design of high performance buildings. They include, for example, shading devices to control illumination, solar heat gains, glare and view-out, and photovoltaic elements imbedded in glazing layers to produce electrical energy on site. However, current methodologies to evaluate the thermal performance of CFS are limited to few products and types. This article develops a general methodology to compute the thermal performance of CFS. The methodology assumes each system layer as porous with calculated effective radiation and thermal properties. A new thermal penetration length model was developed to account for the effects of porous layers on the convective film coefficients of adjacent gas spaces, and applied to various types of shading devices. This methodology is validated using the available measurement and computational fluid dynamics (CFD) simulation results for the U-factor of double-glazed windows with between-pane and internal blinds.     

Ductile moment-resisting frames using cold-formed steel sections: An analytical investigation

This paper presents an investigation on the potential use of cold-formed steel sections (CFS sections) in moment-resisting frames (MRFs) for seismic applications. The main limitation of CFS sections is the low out-of-plane stiffness of their thin-walled elements which leads to low ductility. The main components of MRFs are beams, beam-column connections and columns. In earthquake resistant MRFs, the beams are designed to provide considerable ductility, whereas the other elements are mainly limited to their elastic range. The performance of a new shape of CFS beam with curved flange is examined analytically and compared with that of conventional shapes. The proposed beam-column connections include through plates which potentially limit the out-of-plane action of the forces transferred through the connections. The behaviour of both individual CFS beam sections and CFS beam-column connections is studied by means of finite element analysis (FEA). The results of the analyses show that the new beam cross sections and connections exhibit a good ductile behaviour, something which cannot be achieved by conventional cold-formed frame elements.     

考虑二次受力的碳纤维加固钢筋混凝土梁抗弯性能的试验研究

对 17根考虑二次受力的碳纤维加固钢筋混凝土梁进行抗弯性能试验 ,考虑纵向钢筋的配筋率、碳纤维数量以及加固时的应力水平对加固效果的影响。试验研究表明 ,碳纤维具有良好的加固效果 ,第一阶段应力的存在会使加固效果降低 ,配筋率、碳纤维加固量等对碳纤维的应变影响较大