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.

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.

Experimental seismic behavior of squat shear walls with precast concrete hollow moulds

This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Noncontact lap splices of rebars are used in vertical joints connecting adjacent precast panels for automated prefabrication and easy in situ erection. The seismic behavior of EVE walls was examined through a series of tests on six wall specimens with aspect ratios of 1.0~1.3. Test results showed that EVE wall specimens with inside cast-in situ concrete achieved the desired “strong bending and weak shear” and failed in shear mode. Common main diagonal cracks and brittle shear failure in squat cast-in situ walls were prevented. Inside cast-in situ concrete could signifi cantly improve the shear strength and stiff ness of EVE walls. The details of boundary elements (cast-in situ or prefabricated) and vertical joints (contiguous or spaced) had little eff ect on the global behavior of EVE walls. Noncontact lap splices in vertical joints could enable EVE walls to exhibit stable load-carrying capacity through extensive deformations. Evaluation on design codes revealed that both JGJ 3-2010 and ACI 318-14 provide conservative estimation of shear strength of EVE walls, and EVE walls achieved shear strength reserves comparative to cast-in situ walls. The recommended eff ective stiff ness for cast-in situ walls in ASCE 41-17 appeared to be appropriate for EVE walls.

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.

环氧树脂混凝土装配式桁架下弦K型节点力学试验及有限元分析

通过静力试验研究了环氧树脂混凝土装配式桁架下弦K型节点的破坏形态、承载能力和节点板的应力与应变分布情况,并进行了有限元模拟分析。结果表明:环氧树脂混凝土下弦K型节点在下弦杆靠近节点板的两侧出现5条竖直裂缝,最终节点板左侧下弦杆处的竖直裂缝前后贯通,弦杆发生拉弯破坏,节点的极限承载力为421.5 kN;有限元模拟结果与试验结果吻合较好,验证了有限元模拟的可靠性。

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。

基于ABAQUS的新型密拼叠合板承载能力比较研究

为优化密拼式叠合板侧向拼缝处的连接构造,设计一种在拼缝处设置抗剪键槽的密拼式钢筋桁架叠合楼板。利用ABAQUS有限元软件对7个密拼叠合楼板进行四点弯曲模拟研究,针对普通密拼式叠合板与不同形式的抗剪键槽密拼式叠合板的承载能力进行对比分析。结果表明:新型密拼式叠合楼板的承载能力较好,相较于普通密拼式叠合板提升了17%左右;当达到极限荷载时,其内置钢筋所受应力明显低于普通密拼式叠合板。通过对不同开槽形式叠合板的受弯性能进行对比分析,明确了新型抗剪键槽叠合板拼缝处设计的合理性,为新型拼缝叠合楼板在工程实践中的应用提供了理论依据。

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。

带楼板装配式钢混组合节点抗震性能分析

为了研究楼板组合效应对模块化钢混组合十字形节点抗震性能的影响,在已有试验研究基础上,通过ABAQUS软件建立了模块化钢混组合十字形节点的三维实体模型并进行可靠性验证。在此基础上,分析了轴压比、楼板宽度、楼板厚度和配筋率对节点抗震性能的影响。结果表明,轴压比对节点抗震性能影响显著,轴压比大于0.4时,节点塑性转动性能随轴压比的增大而降低。当楼板宽度增大为1200 mm时,承载力和初始刚度分别降低约25.3%和28.5%,但其对节点的延性和承载力退化影响较小。楼板厚度和配筋率对节点抗震性能影响均较小,可忽略不计。

装配式钢筋混凝土墙板接缝渗漏机理及试验研究

为研究装配式钢筋混凝土建筑接缝渗漏机理,以及风力与缝宽对渗漏的影响,运用毛细动力学原理,以假定无限长的毛细缝渗水为模型,对缝隙中水受力关系进行分析并推导了毛细缝的吸水动力学方程式。在此基础上,还分别研究了风压与缝宽对渗水快慢的影响,并与试验结果进行了对比。研究结果表明:接缝渗漏深度随渗漏时间、裂缝宽度和风压增大而增大。

装配式混凝土石化管廊柱脚节点的抗震性能试验研究

为了研究新型装配式混凝土石化管廊柱脚节点的抗震性能,设计并制作3个足尺的预埋型钢式柱脚节点,并对柱脚节点开展低周反复加载试验:通过分析不同节点的破坏形态和抗震性能参数,研究拉结筋和加载方向对柱脚节点抗震性能的影响。结果表明:各节点的滞回曲线较饱满,具有较强的耗能能力,型钢预留拉结筋能够有效增强预制柱与外包混凝土的连接,设置有拉结筋的节点的抗震性能最佳;沿节点横截面强轴和弱轴施加水平往复荷载下极限承载力相近,弱轴受力下节点具有相对更好的变形能力;3个节点最终破坏均为外包混凝土损坏剥落,预制柱身完好无开裂,3个节点在外包混凝土破坏后承载力无明显下降;基于试验结果分析认为,外露式柱脚的极限承载力可采用规范中的承载力计算公式计算,且计算值与试验值吻合较好。

梁端削弱对模块化栓焊混合节点滞回性能的影响

为了揭示不同梁端截面削弱构造对模块化栓焊混合连接节点抗震性能的影响规律,利用ABAQUS软件建立14个具有梁端截面削弱构造的新型梁柱节点模型,通过试验和参数分析验证节点有限元模型的合理性。研究表明:翼缘和腹板分别单独削弱时,能够减小核心模块和柱端钢骨的应力,增大翼缘连接板处的应力集中。“梁端翼缘+腹板”同时削弱时,能够在梁端削弱截面位置处形成塑性铰,显著减小核心区模块的应力集中和翼缘连接板处的损伤,减小节点的整体变形并提高其耗能能力。研究结论为新型模块化栓焊混合连接节点的工程设计和应用提供理论支撑。

装配式混凝土框架节点抗震性能研究进展

装配式混凝土框架结构,凭借其施工速度快、质量可控及造价低廉等显著优点,已在建筑领域得到广泛应用。然而,在地震易发区,该结构的抗震性能仍待提升。梁柱节点作为该结构体系中的关键部分,其抗震性能研究尤为重要。文中总结了5种常见的装配式混凝土框架梁柱节点连接方式,并深入分析了它们在抗震性能方面的研究进展及各自的优缺点,展望了装配式混凝土框架节点抗震性能研究的未来趋势,为后续相关领域研究者提供参考。

预应力自复位节点有限元合理建模方法研究

预应力自复位结构具有良好的自复位性能,能显著降低震后的残余变形。节点的连接形式影响其自复位性能和抗震能力,为推动此类结构优化设计,需要大量研究分析工作和参数化分析,合理的建模方式可以更有效模拟出结构真实的受力情况。系统探讨了预应力自复位节点有限元分析中的核心问题,通过ABAQUS对内置耗能钢筋预应力自复位节点和角钢耗能预应力自复位节点试验数值模拟,得出结论:对于普通钢筋本构,使用滞回模型结果略好于双折线模型,但整体差异较小;降温法和MPC法均可以较好施加预应力,两者方法效果相同;虚筋法可以较好模拟出预应力筋的滑移,节点承载力和滞回曲线吻合度较高,同时工作量较耦合法和弹簧法更小。

装配式建筑中桁架钢筋混凝土叠合板施工技术研究

针对装配式建筑的施工质量问题,对桁架钢筋混凝土叠合板的接缝施工技术要点及质量控制措施进行了探讨,并结合施工案例进行施工效果分析。结果表明,使用论文所提的施工方法和质量控制措施后,质量问题发生的次数下降了至少41.7%,且施工合格率均在95%以上。

免支撑分块式预制混凝土壁板施工技术研究

为了解决预制装配式混凝土壁板单块重量大、施工时所需支撑多的缺点,以实际工程为背景,设计、施工了一种免支撑分块式预制装配混凝土壁板。壁板接缝处采用UHPC现浇连接段及预埋锚栓干式连接混合作用的节点,达到以下效果:1)在安装阶段,通过预埋螺杆、预埋连接盒的直接连接,可快速提供预制构件安装所需锚固力,降低安装难度;2)在使用阶段,通过超高性能混凝土现浇结合连接的方式提供锚固力,使预制装配式壁板不开裂、渗漏;3)将传统大块壁板分割为较小的块体,降低了单块壁板的重量和体积,便于运输和组装,同时免除了大量的支撑结构,提高了施工效率和质量。

预制装配式框架结构梁柱节点力学性能试验研究

相比钢筋混凝土结构,钢骨混凝土结构因承载力较高和延性较好等诸多优点而应用广泛.以往的研究多数集中于整体式钢骨混凝土框架节点,有关采用钢板对焊拼接形式的预制装配式钢骨混凝土框架节点的研究相对较少.基于以上考虑,设计了两个预制装配式钢骨混凝土框架节点组合体和一个钢筋混凝土框架节点组合体,进行了柱向轴力恒定的拟静力加载试验.对节点组合体的破坏形态、延性、承载力退化、刚度退化和耗能能力作了详细论述.结果表明,轴压比对预制装配式钢骨混凝土框架节点的破坏形态无本质影响;相对钢筋混凝土框架节点,预制装配式钢骨混凝土框架节点具有较高的承载力和较好的延性;预制装配式钢骨混凝土框架节点的塑性变形能力强,具有较好的耗能能力;随轴压比的增大,预制装配式钢骨混凝土框架节点组合体的刚度退化和承载力退化速度提高,延性系数和耗能能力减小;梁连接区和节点核心区的应变随轴压比的增大而减小;框架梁连接区和节点核心区的钢骨和钢筋均未屈服,钢板对焊拼接的连接方式可行.

现浇与预制装配式混凝土框架节点抗震性能试验

为研究预制装配式混凝土框架结构连接节点的抗震性能,探讨其与现浇混凝土框架结构节点之间的性能差异,设计并制作了2组预制装配式混凝土框架节点试件和1组现浇混凝土框架节点试件,通过试验研究试件的滞回特性、承载能力、位移延性、强度退化和耗能能力等抗震性能及其破坏特征。结果表明:通过合理的设计,预制装配式混凝土框架节点的滞回耗能性能与现浇混凝土框架节点相当,其承载力和初始刚度基本等同于现浇混凝土结构节点,但其承载力退化速度快于现浇混凝土框架节点,屈服后预制构件累积损伤程度较现浇构件严重;预制装配式混凝土框架节点在轴压比较大时,节点破坏较为严重,耗能更多。

预制装配式型钢混凝土干式连接节点抗震性能非线性分析

为了通过简便有效的干式连接法将型钢混凝土柱-钢梁进行可靠的连接,提出一种承载耗能、施工高效和节能环保的新型预制装配式型钢混凝土组合节点,针对节点模块与钢梁之间的焊接连接、螺栓连接和栓焊混合连接等3种不同连接方式的梁柱节点,利用ABAQUS进行非线性拟静力分析,得到该新型连接节点的荷载-位移滞回曲线、骨架曲线及其延性与耗能系数.研究结果表明:不同连接方式的新型节点试件滞回曲线饱满,焊接节点、螺栓节点及栓焊混合节点的极限承载力分别为241.7,187.1和198.6 kN,均有稳定的强度及刚度退化性能;节点延性系数依次为6.02,8.24和4.25,等效黏滞阻尼系数依次为0.28, 0.28和0.35,均满足抗震性能的限值要求,表明3种连接方式的节点试件变形性能及耗能能力良好,具有良好的承载能力及抗震性能.

预制装配式混凝土墙板螺栓连接抗剪性能试验研究

为研究预制装配式混凝土墙板螺栓连接的抗剪性能,通过对4个采用装配式螺栓连接的预制墙板结构试件进行单向反复加载试验,获得试件的滞回曲线、骨架曲线、特征荷载与位移;在此基础上对装配式螺栓连接的刚度退化情况以及延性指标进行计算和分析。研究结果表明:装配式螺栓连接具有良好的承载力、刚度及耗能能力,是一种可靠的干连接方式;通过对薄弱部位进行箍筋加密和增加螺栓的个数,能显著提高装配式螺栓连接的抗剪性能。