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 study on box shape steel reinforced concrete beam

Experimental study on the fundamental behavior of box shape steel reinforced concrete （SRC） beams was conducted. Seven 1 ： 3 scale model SRC beams were tested to failure. The experimental results indicate that the flexural strength increases with the increase of the ratio of flexural reinforcement and the thickness of flange of the shape steel; the shear strength increases with the increase in the thickness of the web of the shape steel. Concrete filled in the box shape steel can prevent the early failure of specimens due to the buckling of the box shape steel, and increase the ultimate load. Measures should be made to strengthen the connection and co-work between the shape steel and the concrete. Formulae for flexural and shear strength of the composite beams are proposed, and the calculated results are in good agreement with the experimental results. In general, the box shape SRC beam is a kind of ductile member, and it is suitable for extensive engineering application.

Research on Bond-Slip Constitutive Relation for Steel Reinforced Concrete Members

The constitutive relation of bond-slip on steel and concrete interface is proposed for short steel reinforced concrete （SRC） column. Based on the experimental research on bond-slip performance, a mechanical model of short SRC column in pulling or pushing test is established. By means of the elasto-plasticity theory the explicit formulation of bond-slip constitutive relation τ-s in different anchor-hold place of push and pull member is investigated under the conditions of balance and boundary. The study shows that the constitutive relation is relevant to the embedment length and the thickness of concrete cover. The results are continuous descriptions of bond-slip constitutive relation and can be used to analyze the non-linear performance of SRC members. Results indicate that the principle of the method is correct and it performs well for short SRC column.

预制梁端削弱型钢梁-SRC柱组合节点抗震性能数值分析

为了进一步研究预制梁端削弱型钢梁-钢骨混凝土(steel reinforcement concrete,SRC)柱组合节点的抗震性能,在验证有限元数值模型可靠性的基础上,通过ABAQUS建立了6个梁端削弱构造形式的有限元节点模型,分析不同构造形式对节点滞回性能、弯矩-转角曲线、延性性能及性能退化的影响规律。结果表明:仅梁端翼缘削弱时,对节点耗能性能、承载能力、延性变形以及强度和刚度性能退化影响较小;随着梁端翼缘和腹板同时增加削弱尺寸程度,可显著提高节点耗能能力,最大增幅约为31.25%;承载力总体呈现降低的变化趋势,最大降低仅为7.0%;延性性能提高10.66%;对强度退化性能略有改善。选用翼缘和腹板同时削弱的构造形式,可改善节点的耗能能力和延性性能。

Study on the interfacial shear behavior of steel reinforced concrete （SRC） members with stud connectors after fire

Statically push-out tests of 20 steel reinforced concrete short columns （SRCSC） with stud connectors on the surface of shape steel after fire and two SRCSC under ambient temperature were carried out, in order to study the failure mode, load-slip relationship and the interfacial shear transfer of SRC members after fire. Experimental results show that the typical failure modes and load-slip curves of SRCSC after fire are almost the same as the case under ambient temperature. The interfacial shear transfer of SRCSC declines exponentially not only with the increase of the peak temperature the specimen experienced but also with the increase of the peak temperature duration. The interfacial shear transfer of the specimens with studs arranged at the steel web is much higher than those with studs arranged at the steel flange. Empirical formulas of SRCSC interfacial shear transfer after fire are proposed, and the calculated results generally agree well with the experimental results.

乌兹别克斯坦9度区某超高层建筑结构设计与优化

对于9度设防地区的超高层建筑,其结构设计基本由地震作用控制,因此抗震设计尤为重要。建筑消能减震技术可在提高结构地震安全储备的同时,降低整体工程造价,是结构优化设计的有效措施。对位于9度区的超高层建筑进行了结构方案选型对比、结构方案优化、减震设计方案比选、剪力墙内嵌钢板优化。结果显示,钢骨混凝土框架⁃核心筒方案相对于钢框架⁃支撑方案具备更高的成本优势;框架⁃核心筒方案可通过精细化设计作进一步优化;在此基础上,对钢骨混凝土框架⁃核心筒方案采用两种消能减震方案进行比选,结果表明,采用黏滞阻尼器方案的结构抗震性能明显优于采用黏滞阻尼墙方案;最后通过增大剪力墙竖向分布钢筋配筋率,对低区核心筒墙肢中的内嵌钢板进行了优化。

焊接栓钉型钢混凝土柱压-扭复合受力滞回性能试验研究

为研究焊接栓钉型钢混凝土(stud steel reinforced concrete, SSRC)柱的抗扭性能,提出了6种栓钉布置形式(翼缘、腹板、对称、交错、单双、X型),通过7根SSRC柱和1根型钢混凝土(steel reinforced concrete, SRC)柱的压扭低周反复试验,研究了SSRC柱在压扭复合受力作用下的受力性能。试验观察了SSRC柱在压扭复合受力状态下的破坏形态,揭示了其受扭破坏机理,对比分析了轴压比和栓钉布置形式对试件扭矩-扭转角滞回曲线、骨架曲线、刚度退化、扭转耗能及延性性能的影响规律。结果表明:在压扭复合受力状态下,SSRC柱的扭矩-扭转角滞回曲线呈“S”形,扭转裂缝倾角介于45°~60°之间且随轴压比增大而增大;6种栓钉布置形式均可有效延缓SSRC柱的受扭开裂,腹板焊接栓钉后试件的抗扭承载力提高11.9%;增大轴压比可有效提高SSRC柱的初始抗扭刚度和耗能能力,但会降低其扭转变形能力;栓钉“对称”、“腹板”、“X型”布置时SSRC柱的扭转累积耗能分别提高约16.4%、11.8%、10.2%;综合对比各项指标发现,栓钉“对称”布置对型钢混凝土结构压扭性能的改性效果最佳。

SRC-RC竖向混合结构过渡层抗震设计方法探讨

首先介绍了SRC-RC竖向混合结构的受力特点和性能优势;并针对我国和日本的相关规程及工程应用实践,结合日本阪神地震中SRC-RC竖向混合结构的主要震害特点,指出国内外SRC-RC竖向混合结构过渡层抗震设计方法所存在的主要问题及不足。在综合分析阪神地震后日本关于SRC-RC竖向混合结构过渡层抗震设计方法的最新研究进展的基础上,提出了SRC-RC竖向混合结构过渡层抗震设计的设计思路和方法,可为SRC-RC竖向混合结构过渡层抗震设计提供参考。

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。

基于现行规范的型钢混凝土柱侧力-位移曲线预测方法研究

型钢混凝土(steel reinforced concrete,SRC)柱因承载力高、刚度大和耐久性能好等优点而被广泛应用于高层结构中。然而,现阶段SRC结构设计普遍基于承载力设计法,基于性能的抗震设计法在SRC结构方面的应用仍待完善。作为基于性能(位移)的抗震设计方法中最重要的一环,现阶段SRC构件的侧力-位移关系评估缺乏规范指导。基于美国现行规范ASCE/SEI 41-17中针对钢筋混凝土构件的相关规定,结合SRC构件的受力与变形特征,提出了发生弯曲破坏的SRC柱在地震作用下的侧力-位移曲线建模方法。该曲线采用约束混凝土强度计算SRC构件的峰值承载力;使用刚度折减法考虑型钢与混凝土之间的黏结滑移;基于SRC构件的变形特征考虑了纵向受力钢材端部滑移对柱顶侧移的贡献。最后,通过与28根SRC柱试验结果的比较证明了曲线的适用性。计算结果表明:所提出的曲线能合理预测发生弯曲破坏的SRC柱的开裂荷载、开裂位移、峰值荷载、峰值位移和强度退化,可为SRC结构的性能化抗震设计提供参考。

SRC不等肢L形截面异形柱正截面承载力研究

在试验研究的基础上,对型钢混凝土(SRC)不等肢L形截面异形柱的正截面承载力进行有限元数值分析,利用数值迭代法编写了SRC不等肢L形截面异形柱承载力计算程序,由该程序可求得SRC不等肢L形截面异形柱正截面承载力的N-M及Mx-My相关曲线,并能得到其极限承载力,计算结果与试验结果吻合较好;通过计算可知,SRC异形柱比相同截面的钢筋混凝土(RC)异形柱正截面承载力提高很多;最后给出了SRC异形柱的实用设计计算步骤.

基于层次分析遗传算法的SRC框架梁优化设计

文章将SRC框架梁的工程造价最小和正截面抗弯承载力最大定为优化目标,并对其进行无量纲化处理,使得多目标的优化问题转化为单目标优化问题。采用线性加权法构造评价函数,通过调整加权系数来改变2个优化目标在优化中的重要程度,通过算例给出合理取值,为组合结构的多目标优化问题提供参考。SRC构件中的型钢腹板及翼缘的高度、宽度等对梁的受力状态所做的贡献不同,通过引入层次分析法理论,在遗传算法的编码过程中对各变量进行权重赋值,使得对构件受力影响较大的单元赋予较大的权重,从而更好地发挥各组成部分的作用。

碳纤维布加固震损SRC柱抗震性能有限元分析

为了深入研究碳纤维布加固震损型钢混凝土(SRC)柱的抗震性能,基于试验研究,采用材料性能折减的方法考虑震损的影响,应用有限元分析软件ABAQUS对碳纤维布加固震损型钢混凝土柱的抗震性能进行模拟计算,计算结果与试验结果吻合良好。通过数值计算,分析了轴压比、碳纤维布加固量和地震损伤程度对加固效果的影响。分析表明,采用材料性能折减的方法是考虑震损对构件性能影响的一种有效可行方法;在轴压比0.2~0.5范围内,轴压比增加使型钢混凝土柱的极限位移减小;在碳纤维布加固层数1~3范围内,碳纤维布层数增加能提高型钢混凝土柱的极限承载力和极限位移;地震损伤程度达到0.6时,加固修复型钢混凝土柱抗震能力未能恢复至原构件。

扭弯比对SRC柱抗震性能影响的试验研究与分析

为研究扭弯比对弯曲和扭转复合作用下型钢混凝土组合(SRC)柱的受力及变形性能影响,以扭弯比为主要控制参数对7个SRC柱进行了弯矩和扭矩成比例加载的低周往复试验,研究分析了扭弯比对SRC柱的破坏特征、滞回性能、承载力以及变形等特征的影响规律,并建立了SRC柱在弯扭复合作用下的抗弯、抗扭承载能力及变形计算方法。研究结果表明:扭弯比是影响SRC柱抗震性能的主要参数,扭弯比参数决定了SRC柱的破坏类型;弯扭复合作用降低了SRC柱的抗弯、抗扭承载能力,但扭弯比对弯曲和扭转存在相反的影响;弯矩与扭矩成比例往复加载相比定扭矩弯矩往复加载,抗弯和抗扭承载力的相互影响程度减小且偏于安全。

内配圆钢管的SRC轴心受压短柱的力学性能

在合理选取钢材和混凝土本构模型的基础上,利用ABAQUS软件建立了内配圆钢管的SRC轴压短柱力学性能分析模型,对其在轴压荷载下的荷载-变形关系全过程曲线、典型破坏形态、荷载分配及承载力进行了较全面的分析。结果表明:钢管外箍筋约束混凝土和钢管约束核心混凝土在轴压荷载作用下最先进入塑性阶段,接着钢管外箍筋约束混凝土达到极限承载能力,外围钢筋混凝土相对内部钢管混凝土承担更多的荷载。钢管内混凝土强度、钢管外混凝土强度、钢管屈服强度、截面含钢管率、纵筋配筋率、体积配箍率和位置系数是影响内配圆钢管的SRC轴压短柱承载力的主要因素。分析结果可为相关工程应用提供参考。

SRC-RC竖向混合结构转换柱承载力与延性性能分析

以16根转换柱试件和1根钢筋混凝土柱对比试件的低周反复荷载试验为基础,分析了转换柱的承载力与延性性能。研究了钢与混凝土之间的相互作用方式,确定了型钢局部存在对转换柱力学性能的影响。型钢的配钢率、轴压比、型钢延伸高度及体积配箍率是影响承载力与延性性能的主要因素:配钢率越大,转换柱的承载力越大,位移延性系数越小;轴压比越大,转换柱的承载力越大,位移延性系数越小;型钢延伸高度对转换柱的承载力影响较小,而位移延性系数随着型钢延伸高度的增加呈现出先升后降的变化规律,当延伸高度达到3/5的柱高时位移延性系数达到最大值;随着体积配箍率的增加,转换柱的承载力与位移延性系数同时增大,增长速率与配钢率有关,配钢率较大试件的承载力与位移延性系数随体积配箍率的增长速率更快。

爆炸荷载作用下SRC柱中混凝土的断裂破坏原理

以计算机模拟为手段,研究分析了SRC(Steel-Reinforced-Concrete,简称SRC)柱在爆炸冲击荷载作用下钢骨周围混凝土的断裂破坏原理。发现由于所受爆炸冲击波荷载性质的不同,SRC柱中的混凝土可以分为3种破坏模式:冲击波直接破坏、冲击波冲量破坏和冲击波能量破坏。该研究成果不仅为进一步研究SRC柱在爆炸冲击荷载作用下的破坏模式提供了研究基础,并且为SRC柱的抗爆设计和抗爆加固提供了指导作用。

型钢混凝土结构(SRC)设计规程比较

首先对日本及欧美等国外有关型钢混凝土(SRC)结构的设计规程进行了介绍,并简单介绍了我国现有的关于型钢混凝土(SRC)结构的两部规程《钢骨混凝土结构设计规程》(YB 9082-97)及《型钢混凝土组合结构技术规程》(JGJ 138-2001)的编制背景和依据。对两部规程中有关型钢混凝土梁的正截面抗弯、斜截面抗剪承载能力、型钢混凝土(SRC)偏心受压构件、剪力墙和梁柱节点的计算理论和计算方法进行了重点比较分析,并结合型钢混凝土(SRC)梁、型钢混凝土(SRC)偏心受压构件和梁柱节点承载能力的计算实例,对两部规程的应用方法、计算步骤和计算结果做了比较分析,为使用两部型钢混凝土结构设计规程提供参考。

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。