Seismic Behaviour of Beam-Column Joints of Precast and Partial Steel Reinforced Concrete

A beam-column joint of precast and partial steel reinforced concrete( PPSRC) is proposed for precast reinforced concrete frames. The PPSRC consists of partial steel and reinforced concrete. The partial steel is located in the core joint region and the connections between concrete members. This paper presents an experimental study of a series of PPSRC specimens. These specimens are tested under low cyclic loading.Experimental results demonstrate that the bearing capacity of the PPSRC specimens is 3 times that of the ordinary reinforced concrete( RC) beam-column joints. The strength and stiffness degradation rates are slower compared with that of the RC beam-column joints. In addition,the strength of the core joint region and the connections is higher than other parts of the PPSRC specimens. Beam failure occurs firstly for the PPSRC specimens,followed by column failure and connections failure. The failure of the core joint region occurs finally.Test results show that the seismic performance of the PPSRC is better than that of the ordinary RC beam-column joints.

Static behavior of semi-rigid thin-walled steel-concrete composite beam-to-column joints with bolted partial-depth flush end plate:experimental study

A new type of semi-rigid thin-walled steel-concrete composite beam-to-column joint has been proposed in this paper.Five semi-rigid composite beam-to-column joint specimens subjected to hogging moments under monotonic loading were tested to study the static behavior of this new type of joint.The main variable parameters for the five joint specimens were the longitudinal reinforcement ratio and the joint type.The experimental results designated that the magnitude of extension of the longitudinal reinforcement is the most important factor that influenced the moment-rotation characteristic of the new type of joint.The concrete slabs could resist 3.8%-19.1% of the total shear load applied to the cross-sections near the beam-to-column connection.The edge stiffened elements,such as the flange of the lipped I-section thin-walled steel beam,were capable of having considerable inelastic deformation capacity although they had comparatively large width-to-thickness ratios.The shear failure of the concrete cantilever edge strip must be taken into account in practical design because it has significant influence on the anchorage of the longitudinal reinforcement in the new type of external joints.

Seismic performance of steel reinforced ultra high-strength concrete composite frame joints

To investigate the seismic performance of a composite frame comprised of steel reinforced ultra high-strength concrete （SRUHSC） columns and steel reinforced concrete （SRC） beams, six interior frame joint specimens were designed and tested under low cyclically lateral load. The effects of the axial load ratio and volumetric stirrup ratio were studied on the characteristics of the frame joint performance including crack pattern, failure mode, ductility, energy dissipation capacity, strength degradation and rigidity degradation. It was found that all joint specimens behaved in a ductile manner with flexural-shear failure in the joint core region while plastic hinges appeared at the beam ends. The ductility and energy absorption capacity of joints increased as the axial load ratio decreased and the volumetric stirIup ratio increased. The displacement ductility coefficient and equivalent damping coefficient of the joints fell between the corresponding coefficients of the steel reinforced concrete （SRC） frame joint and RC frame joint. The axial load ratio and volumetric stirrup ratio have less influence on the strength degradation and more influence on the stiffness degradation. The stiffness of the joint degrades more significantly for a low volumetric stirrup ratio and high axial load ratio. The characteristics obtained from the SRUHSC composite frame joint specimens with better seismic performance may be a useful reference in future engineering applications.

基于CTM和Beam-Column Joint Element的梁柱节点核心区抗剪仿真

为研究基于CTM和Beam-Column Joint Element单元的钢筋混凝土梁柱节点核心区抗震仿真计算,本文先分析了CTM的计算原理和局限性,并对原计算模型进行调整;之后通过试验数据验证了调整前后模型的正确性,并通过参数分析得出调整前后CTM在不同参数下核心区抗剪强度的变化规律;最后通过对比理论计算与试验下核心区抗剪强度变化规律,证明调整后模型更为准确。

Rapid Repair of Earthquake Damaged RC Interior Beam-wide Column Joints and Beam-wall Joints Using FRP Composites

This paper studies the seismic performance of FRP-strengthened RC interior non-seismically detailed beam-wide columns and beam-wall joints after limited seismic damage.Four eccentric and concentric beam-wide column joints and two beam-wall joints,initially damaged in a previous study,were repaired and tested under constant axial loads(0.1fc′Ag and 0.35fc′Ag) and lateral cyclic loading.The rapid repair technique developed,aimed to restore the original strength and to provide minimum drift capacity.The repair schemes were characterized by the use of:(a) epoxy injections and polymer modified cementitious mortar to seal the cracks and replace spalled concrete;and(b) glass(GFRP) and carbon(CFRP) sheets to enhance the joint performance.The FRP sheets were effectively prevented against possible debonding through the use of fiber anchors.Comparison between responses of specimens before and after repair clearly indicated reasonable restoration in strength,drift capacity,stiffness and cumulative energy dissipation capacity.All specimens failed with delamination of FRP sheets at beam-column joint interfaces.The rapid repair technique developed in this study is recommended for mass upgrading or repair of earthquake damaged beam-column joints.

Study on Strengthening of RC Beam Column Joint Using Hybrid FRP Composites

Beam-Column joints are critical zones in reinforced concrete structures which are most vulnerable to earthquake forces. Hence strengthening beam-column joint is vital to save the structure and its inhabitants in case of seismic forces. Numerous retrofitting works using fibre reinforced polymer (FRP) composites are being undertaken worldwide. This work aims to investigate the effectiveness of strengthening beam-column joints using natural and artificial fibres. In this study, basalt (natural fibres) as monolithic composite (BFRP) and as hybrid composite along with glass (artificial fibres) were used for strengthening of beam-column joints. Totally six specimens were prepared and tested under monotonic loading. Specimen details used were: two control specimen, two specimens for monolithic wrapping and remaining two specimens for hybrid wrapping. The test results were compared with control and rehabilitated specimens. The performance of the treated joints was studied using the following parameters: initial and ultimate cracking loads, energy absorption, deflection ductility and stiffness at ultimate. From the test results, it was found that the hybrid combination of Basalt and Glass FRPs were found to be more effective in the treatment of beam-column joints. The strong column weak beam concept was achieved by failure in beam portion which helped in preventing the catastrophic failure of the entire structure.

基于转动摩擦铰阻尼器的干式装配梁-柱节点抗震性能试验

基于转动摩擦铰阻尼器(RFHD),提出了转动摩擦耗能干式装配梁-柱节点(DRFDBJ)。为了验证DRFDBJ结构对于实现预期力学性能的可行性和合理性,以施加在摩擦片表面的螺栓预紧力(P_(c))为变量,开展了2个工况下的DRFDBJ试件低周往复拟静力试验研究。结果表明:DRFDBJ结构的力学性能主要由RFHD提供并控制,试验中节点呈现了稳定的承载力和理想的变形、耗能能力,并实现了预期的损伤集中;2个不同P_(c)水准下节点承载力的试验值与理论值误差不超过5%,通过调整P_(c)可实现节点承载力的调控,为DRFDBJ结构承载力的可调控提供了支撑。

新型钢管混凝土梁柱节点力学性能试验研究

为研究内加强环式圆钢管混凝土柱与矩形钢管混凝土梁这种新型连接节点的力学性能,设计了缩尺钢管混凝土梁柱节点试件,开展了相同梁柱节点试件的静力加载试验和低周往复加载试验。通过研究该节点试件的破坏模式、荷载-位移曲线以及拟静力加载试验的骨架曲线、核心区剪切变形等,分析了节点试件的承载能力、延性和耗能能力,全面考察了同一梁柱节点在静力加载和低周往复加载两种工况下的受力性能和破坏模式。结果表明:钢管混凝土梁柱节点试件核心区强度较强,破坏模式主要为梁端破坏,低周往复加载试验时试件梁柱连接处附近的梁端钢板发生拉裂破坏和钢板鼓曲,静力加载试验时试件梁端焊缝发生拉裂破坏;试件延性较好,加载过程中经历了弹性、弹塑性和塑性发展阶段。最后提出了该类钢管混凝土梁柱节点核心区的抗剪强度计算公式。

横向贯通式中低速磁浮一体轨道梁钢-混结合部试验研究

为解决中低速磁浮分离式轨道梁存在的养护难、构件多,以及无法考虑F轨刚度贡献等问题,提出一种横向贯通式梁轨一体轨道梁结构,针对其钢-混结合部的静力性能开展有限元分析和足尺模型试验研究,并对关键设计参数进行参数分析。结果表明,在5倍设计荷载内,钢-混结合部基本处于弹性状态,承载力满足设计要求,且具备较高富裕量;竖向荷载主要通过钢板承压作用传递至混凝土梁体,焊钉对竖向荷载的传递作用较小;设计参数分析表明,适量提高钢连接件钢板厚度有利于竖向荷载的平顺传递。研究结果可以为梁轨一体轨道梁设计提供参考。

开槽侧板加强型连接梁柱节点子结构抗连续倒塌性能研究

为了优化侧板加强型节点的抗连续倒塌性能,提出了一种开槽侧板加强型梁柱连接节点形式。通过静力加载试验,得到了新型节点子结构的破坏模式、竖向抗力发展机制、应变分布、延性水平和动力承载力等。试验结果表明:钢梁翼缘在盖板附近首先开裂并向腹板外排螺栓中部延伸贯穿,导致竖向承载力快速下降为峰值荷载的20%左右。相比传统侧板加强型和圆弧扩盖板型梁柱节点,新型节点的峰值承载力分别提高了62.1%和19.6%,塑性弦转角分别提高了203.6%和25.8%。通过有限元分析得到了试件的断裂路径发展过程,进一步地通过参数化分析发现:扩大过焊孔构造对改善峰值后塑性弦转角及残余强度提升无明显作用;随着螺栓群远离钢梁翼缘起始断裂位置,最小残余强度比不断增大,但峰值后塑性弦转角呈先增大后减小的趋势;当螺栓群内移45mm时,峰值后塑性弦转角及最小残余强度比分别达到0.149rad和0.88,提高了38.2%和200.8%。

混凝土梁柱节点带锚固板钢筋锚固性能试验研究

为研究混凝土梁柱节点带锚固板钢筋锚固性能,共设计33个满足现行规范构造要求的拟梁柱节点试件,通过静载试验分析混凝土强度、锚固长度、锚固板尺寸、箍筋间距等参数对带锚固板钢筋锚固承载力的影响;通过拟合试验数据得到带锚固板钢筋锚固力经验公式,提出带锚固板钢筋锚固长度设计建议,并基于试验数据库对建议公式以及中国规范公式进行了统计分析。结果表明:混凝土强度、钢筋锚固长度和锚固板面积对带锚固板钢筋锚固承载力有较大的影响,而承载力对箍筋间距不是很敏感;锚固板分担的锚固力占总锚固力的70%以上,中国规范对锚固板分担占比的规定偏小,对锚固长度的规定偏于不安全;建议现浇框架中间层梁柱角节点带锚固板钢筋的锚固长度调整为0.45 l_(ab)(l_(ab)为中国规范的基本锚固长度),中间层梁柱边节点的锚固长度可不作调整。

钢管混凝土柱-钢梁连接节点形式与研究进展

钢管混凝土结构体系中,梁柱节点的受力状态复杂,是结构体系中的关键连接部位,对结构的承载力、刚度以及稳定性能均有重要影响。对国内外钢管混凝土柱-钢梁连接节点的相关研究进行了全面的综述,总结了内加强型连接节点、外加强型连接节点、贯通式连接节点、螺栓连接节点等各类钢管混凝土柱-钢梁连接节点形式的特点和已有研究,从承载力、刚度、破坏模式、抗震性能、设计方法等方面对各类连接节点的优势和存在的问题进行了分析和归纳。旨在为钢管混凝土柱-钢梁连接节点的相关研究提供参考,促进钢管混凝土柱结构体系的研究和工程应用。

高强螺栓工字钢连接混凝土梁柱节点的抗震性能研究

目的提出一种以高强螺栓工字钢连接混凝土梁柱节点的连接方法,研究该节点抗震性能,为工程设计提供依据。方法采用ABAQUS有限元软件模拟节点的受力过程,研究后浇混凝土强度、节点区长度、工字钢翼缘厚度等参数对节点抗震性能的影响。结果与现浇结构相比,新型节点承载能力更高,其屈服荷载和峰值荷载相较于现浇试件的屈服荷载和峰值荷载分别提升2.08倍和2.64倍;提高后浇混凝土强度等级、增加节点区的长度对承载能力影响较小;提高工字钢翼缘厚度、工字钢屈服强度,节点的承载能力提高较明显。结论采用高强螺栓工字钢连接混凝土梁柱节点的连接结构满足承载力要求,且工字钢翼缘厚度、工字钢屈服强度对结构的承载能力影响较大。

装配式混凝土梁柱节点连接形式研究进展

装配式混凝土结构的发展是建筑行业转型升级路上的重要一环,而梁柱节点是装配式框架体系的关键部分。预制梁、柱的连接根据是否二次浇筑混凝土可分为湿式连接和干式连接。以连接形式为切入点,对国内外装配式混凝土梁柱节点的研究现状进行归纳,重点介绍节点连接形式研究的最新进展,提出未来研究方向以及可能存在的问题。

预应力混凝土梁-型钢混凝土柱新型框架节点受剪承载力计算方法

梁柱节点受剪承载力计算是混凝土框架结构节点抗震设计的关键点之一,由于节点剪力传递机理与构造的复杂性,目前尚未形成完善的节点受剪承载力计算理论。该文阐述了预应力混凝土梁-型钢混凝土柱新型框架节点的受力机理,并基于桁架模型和斜压杆模型,提出了一种同时考虑预应力筋与型钢贡献的节点受剪承载力计算方法。开展了新型节点受力性能拟静力试验,分别选取了梁端破坏与节点剪切破坏两种破坏形式的节点试验数据,对所建立的新型节点受剪承载力计算方法进行了验证评估,结果表明,该文提出的预应力混凝土梁-型钢混凝土柱框架节点承载力计算方法具有较好的精度。

UHPC-RC节段组合梁的抗弯性能分析

为研究低预应力度条件下,不同节段接缝的超高性能混凝土-钢筋混凝土(ultra-high performance concrete-reinforced concrete,UHPC-RC)组合梁的抗弯性能,文章基于ABAQUS有限元软件,建立UHPC-RC节段组合梁的基准有限元模型,并利用已有的试验数据验证该模型的合理性。节段接缝分别为平面干接缝、平面胶接缝、齿键干接缝和齿键胶接缝,在基准有限元模型的基础上,进一步研究节段接缝类型对组合梁抗弯性能的影响。研究发现,在四点受弯加载方式下,接缝的几何特征(平面或齿键)对组合梁的极限荷载和开裂荷载影响较小,环氧树脂胶的使用对组合梁的抗弯性能影响较大。

钢管混凝土扁柱-钢梁节点抗震性能有限元分析

为避免钢框架结构中梁柱节点凸出墙体,文章提出一种钢管混凝土扁柱与钢梁节点,采用ABAQUS有限元模拟软件建立4个不同连接位置的钢管混凝土扁柱-钢梁节点的有限元模型,分析节点在低周往复荷载下的破坏模式和抗震性能;结果表明,所提出的节点构造可以实现梁柱刚性连接,所有节点均发生梁铰破坏,抗震性能和耗能能力良好。进一步研究轴压比、竖向隔板厚度和连接构造对节点抗震性能的影响规律,结果表明:随着轴压比的提高,柱端峰值承载力随之下降;减小柱内竖向内隔板的厚度会导致柱端承载力的降低;将盖板连接改为竖向加劲肋连接后,能有效缓解节点处柱壁的应力集中现象。

冷弯型钢钢管混凝土柱-钢梁装配式节点抗震性能研究

为考察多高层框架结构体系中新型冷弯型钢装配式钢管混凝土柱-冷弯型钢拼合梁节点的抗震性能,设计并制作了一组足尺节点试件,对其进行不同轴压比下的拟静力试验.结合ABAQUS有限元分析,以轴压比、钢管柱壁厚、内填充混凝土强度等级为主要参数,研究节点试件在低周往复水平荷载作用下的破坏形态、滞回曲线、骨架曲线、承载力、耗能能力、刚度退化等抗震性能.结果表明:在冷弯型钢柱内填充混凝土时,新型冷弯型钢装配式梁柱节点的承载力和耗能能力相比于空钢管柱节点整体有所提高,节点延性增加,节点仍保持“强柱弱梁”的失效模式.在低轴压比(0.2)下,钢管柱壁厚的增加对节点的耗能能力与承载力有一定的提升,其延性也有所增加;混凝土强度等级的变化对本文所研究“强柱”构造下的节点抗震性能几乎无影响,节点的滞回曲线基本一致,骨架曲线基本重合,节点的破坏形态保持不变,随着混凝土强度等级的增加,节点延性有所降低.但在高轴压比(0.8)下,钢管柱壁厚为2 mm和3 mm时柱刚度过弱,节点出现柱端压弯破坏;当钢管柱壁厚增加到4 mm时,节点破坏形态转变为梁端塑性铰破坏,因此应注意限制梁柱线刚度比,保证“强柱弱梁”的失效模式.本文研究成果对该新型节点用于多高层框架结构体系中的适用性及设计构造有一定参考意义.

装配式混凝土框架混合连接中节点抗震性能模拟

基于框架结构“强节点弱构件”的抗震需求和节点易于实现可靠连接,提出一种新型钢筋混凝土框架装配式混合连接节点形式。考虑梁端刚/柔性两种连接方式,采用有限元软件ABAQUS建立2个新型钢筋混凝土框架装配式混合连接中节点模型和1个现浇对比试件模型,并对其进行水平循环往复荷载下的抗震性能模拟。根据模拟数据整理,对试件滞回性能、节点转动刚度、耗能能力和破坏模式进行对比分析。研究结果表明:装配式混合连接节点采取钢管混凝土实现了节点区混凝土斜压带和钢板斜拉带协同抗剪机理,提高了节点核心区抗剪能力,更好地满足“强节点”的抗震需求;装配式连接节点梁端刚/柔性连接方式均不同程度实现了梁端塑性铰区远离节点区;梁端刚性连接装配式连接节点试件的塑性铰区距离节点区最远,其整体性最好,初始抗弯刚度最大;梁端柔性连接装配式连接节点试件的塑性铰区范围较大,损伤耗能发展持续,而梁端刚性连接试件的塑性铰区相对集中,损伤耗能发展快速充分。

某超高层项目钢管混凝土组合柱应用

某超高层项目荷载较大,导致框架柱截面较大,严重影响建筑空间使用。采用钢管混凝土组合柱,和型钢混凝土柱相比,标准层每根柱节约建筑有效使用面积1.5~1.8m^(2),结构主体成本节约近1000万元。提出了对钢管进行开孔的梁柱节点做法并分析五种不同节点方案,采用大型通用有限元软件ABAQUS进行仿真分析,充分考虑框架梁对节点的约束作用,得到五种节点方案的极限承载力及钢管的最大应力,结果表明采用钢管开孔的梁柱节点做法可行,并得到最合理的开孔形式;分别对7种不同箍筋形式进行受力性能分析,并考虑实际施工因素,得到最为合理的箍筋设置形式。