Experimental investigation of slab joints between existing buildings and new frames for vertical expansion; [Part I]

Vertical additions can be made to existing buildings to provide more residences while avoiding the need to fully dismantle and reconstruct the buildings. Super‐structural frames consisting of shallow composite beams and steel columns can be prefabricated as modular units, replacing the wall frames that are conventionally constructed in existing bearing wall buildings. A lightweight modular construction introduced in this study minimizes the needed structural reinforcement of frames below, enabling quicker and safer assembly of frames relative to traditional wall frame construction. This paper introduces joint details between added steel columns and existing slabs. Extensive experimental investigations were performed to study the structural behavior of the suggested joints. Eight full‐scale specimens were loaded to failure to evaluate the structural applicability and reliability of the connecting methods introduced in this study, and to identify any problems with the vertical additions. The present work was also intended to find effective design procedures to those issues, and to provide test data for use in detailed analytical investigation of the structural behavior. Regardless of the connection method and the failure mode, all specimens demonstrated stable structural performance within the range of loadings that are expected during the service life of vertically extended buildings.     

Experimental investigation of the influence of steel joints upon the flexural capacity of precast concrete columns

In previous studies, the authors have shown that successful modular construction depends on using the correct types of joint connections. In this experimental study, steel beam–column joint connections were shown to be very efficient in facilitating the construction of modular frames while ensuring sufficient flexural moment capacity at the joints to resist lateral loads. This research also included an investigation of the behavior, the crack pattern, and the flexural moment capacity of concrete columns with hybrid composite joints by means of structural experiments on three specimens. Three column specimens were subjected to cyclic loading under displacement control using an oil jack. The influence of including steel sections at the beam–column joint upon the flexural moment capacity of the column was studied, and the use of concrete–steel hybrid composite joints was found to increase the flexural structural performance of the concrete columns. The flexural moment capacity in the maximum load limit state of a concrete column with steel joints was 43.2% greater than that of a conventional reinforced concrete column without steel joints. The steel section in the joint was found to greatly contribute to the flexural moment capacity and to the modular construction technologies.     

A review of the diagrid structural system for tall buildings

Unlike vertical columns of traditional structure, diagrid structural systems for tall buildings have special inclined columns. Due to the inclined columns, a diagrid structural system for tall buildings produces axial force along the column direction under horizontal load, which has the advantage of resisting horizontal wind load and seismic load and gives more freedom to architectural design, so a diagrid structural system for tall buildings becomes an effective new structure style for tall and super‐tall buildings. Theories and tests regarding the diagrid structural system for tall buildings have been intensely researched since the exterior tube of diagrid structural system for tall buildings was first proposed by Torroja in his seminal book. At present, studies for mechanical characteristics, joint form, theories, and tests have been systematized. This paper systematically summarizes existing research achievements of the diagrid structural system for tall buildings and confirms that the structure has larger lateral stiffness and good seismic performance. Based on the favourable performance of concrete‐filled steel tubes, this paper advises the use of concrete‐filled steel tube columns as the columns in diagrid structural systems for tall buildings.     

竖向荷载下足尺半刚性连接组合框架试验研究

为研究半刚性连接组合框架在静载作用下的力学性能,进行了竖向荷载下两榀足尺的两层两跨半刚性连接组合框架试验。组合框架由H型钢柱和压型钢板混凝土组合梁组成,钢节点由焊接到钢梁端部的平端板通过螺栓与钢柱翼缘连接。为了解半刚性连接组合框架的结构性能和破坏特征,考察不同荷载水平作用下半刚性连接和楼板的组合效应对钢框架结构整体性能的影响,重点分析框架整体性能、节点性能和梁性能。试验表明:平端板型组合节点为半刚性连接、部分强度节点,具有较高的强度和刚度,其极限转角可满足不小于30mrad的延性设计要求;半刚性连接和楼板的组合效应对钢框架的强度、刚度和延性有较大影响,设计时应加以考虑。试验结果可为今后半刚性连接组合框架理论研究和工程实际应用提供参考。     

抗震工程中的钢-混凝土组合结构体系分析

过去10年里,美国关于钢-混凝土组合结构体系抗震性能的研究显著增多。介绍了最近一系列组合横向抗力体系的研究成果,包括由钢梁和钢管混凝土柱或型钢混凝土柱组成的无支撑框架,带钢管混凝土柱的支撑框架及各种组合、混杂墙结构。相比于一般体系,该体系在正常使用或极限状态下的性能及材料与结构的经济性等方面都有许多优点。此外,介绍由带钢筋混凝土填充墙的部分约束钢框架组成的组合体系的深入研究成果。最后,总结了未来对这些组合体系设计的可能规定。     

抗震工程中的钢和混凝土组合结构体系分析

过去10年里,美国国内关于钢和混凝土组合体系建筑抗震工程的研究有显著的增多。对最近一系列组合横向阻力系统的研究进行了概述,包括由钢梁和混凝土填充的钢管组成的无支撑框架,带有混凝土填充钢管柱的支撑框架,型钢混凝土柱以及一系列变化的组合混杂墙系统。相对于很多一般的系统,这些结构体系的优点包括它们在承受正常使用或极限荷载时的性能特征,以及材料与结构的经济性。此外,介绍其中一种混合系统深入研究的成果,包括部分约束的带有加强混凝土填充墙的钢框架。总结出这些组合体系将来设计条款的概要。     

外包钢-混凝土组合梁与钢筋混凝土柱节点的试验研究

外包钢-混凝土组合梁是一种新型组合梁,在负弯矩作用下具有良好的工作性能,其与柱连接节点的构造还有待合理设计并试验验证。采用两种不同的构造形式,设计4个外包钢-混凝土组合梁与钢筋混凝土柱的连接节点,并对其进行低周反复荷载作用下的试验研究。对节点的破坏形态、滞回曲线、强度、延性和钢筋、钢板的应变等性能进行分析,结果表明:通过合理的构造措施,外包钢-混凝土组合梁与钢筋混凝土柱的连接节点具有较好的受剪承载力、延性和耗能能力,能够满足工程要求。在此基础上对节点的受力机理进行探讨,提出节点核心区受剪承载力的计算公式,计算结果和试验结果吻合良好。     

Innovative Betone für Holz‐Beton‐Verbundkonstruktionen

Innovative concretes for timber‐concrete composite constructions. Timber‐concrete composite constructions are currently applied mainly for new buildings or when strengthening existing timber beam slabs. The load bearing capacity of timber‐concrete composite slabs is essentially affected by the material properties of the concrete slab and timber beam itself as well as the efficiency of bond between both parts. As nowadays a wide spectrum of different innovative concretes is available their applicability for timber‐concrete composite constructions has to be verified. In the following the focus is set for self‐consolidating concrete, steel fibre reinforced concrete, structural lightweight concrete, high‐strength and ultra high‐strength concrete. The advantages but also disadvantages of these concretes will be explained considering structural, economic and processing aspects and building physics.     

T形钢管混凝土柱-工字钢梁框架顶层边节点抗震性能试验研究

选择T形截面钢管混凝土异形柱-工字钢梁框架顶层边节点为研究对象,按1∶2的缩尺比例设计并制作3个“弱节点”模型和1个“强节点”模型,通过施加恒定轴压比的竖向荷载和低周往复水平荷载,对节点模型进行加载破坏试验,观察节点模型的受力过程和破坏形态,得到水平荷载-柱端位移滞回曲线和骨架曲线,分析节点荷载特征值、延性、耗能以及刚度退化等。试验结果和分析表明：弱节点试件破坏形态主要为节点核心区在剪压复合应力作用下的剪切破坏,随轴压比增大,试件受剪承载力提高,但其延性和耗能能力有所下降;强节点试件破坏形态为钢梁的局部屈曲破坏,节点区基本完好,滞回曲线饱满,延性系数为3.89;合理地设计钢管混凝土异形柱-钢梁框架边节点,可满足抗震延性要求,实现“强柱弱梁,节点更强”的抗震设计目标。     

单边高强螺栓连接方套方中空夹层钢管混凝土柱组合节点抗震性能试验研究

为了深入研究单边高强螺栓连接中空夹层钢管混凝土柱组合节点的抗震性能和破坏机理,对4个方套方中空夹层钢管混凝土柱与钢-混凝土组合梁单边高强螺栓端板连接节点进行了低周反复加载试验,以端板形式和柱截面空心率为主要试验参数,考察了节点破坏模式和组合楼板裂缝分布规律,研究节点滞回曲线、连接弯矩-转角关系、刚度和承载力退化、延性和...     

Optimum structural modelling for tall buildings

It is a common practice to model multi‐storey tall buildings as frame structures where the loads for structural design are supported by beams and columns. Intrinsically, the structural strength provided by the walls and slabs are neglected. As the building height increases, the effect of lateral loads on multi‐storey structures increases considerably. The consideration of walls and slabs in addition to the frame structure modelling shall theoretically lead to improved lateral stiffness. Thus, a more economic structural design of multi‐storey buildings can be achieved. In this research, modelling and structural analysis of a 61‐storey building have been performed to investigate the effect of considering the walls, slabs and wall openings in addition to frame structure modelling. Sophisticated finite element approach has been adopted to configure the models, and various analyses have been performed. Parameters, such as maximum roof displacement and natural frequencies, are chosen to evaluate the structural performance. It has been observed that the consideration of slabs alone with the frame modelling may have negligible improvement on structural performance. However, when the slabs are combined with walls in addition to frame modelling, significant improvement in structural performance can be achieved. Copyright © 2012 John Wiley & Sons, Ltd.     

钢筋混凝土柱-钢梁组合框架节点研究进展

钢筋混凝土柱-钢梁(RCS)组合框架是一种新型组合结构体系,它充分地利用和发挥了钢和钢筋混凝土构件各自的优点,是一种低成本、高效率的结构形式.系统地介绍了RCS组合节点和组合框架的研究和应用背景,阐述了RCS组合节点和组合框架的国内外研究现状,重点评述了RCS组合节点的试验研究和数值模拟研究两个方面的进展情况,介绍了RCS组合节点的抗震性能.最后,指出了RCS组合框架结构研究存在的问题和今后的发展趋势.     

不同构造竖缝的装配式空心模板剪力墙抗震性能试验研究

通过1个钢筋混凝土剪力墙和4个装配式空心模板剪力墙的拟静力试验,研究了剪力墙的抗震性能及竖向接缝构造对墙体受力性能的影响。试验结果表明,装配式空心模板剪力墙沿内部接缝出现宏观竖向裂缝,经历了整截面墙受力到墙柱组合体受力的过程,可防止脆性破坏,较钢筋混凝土剪力墙变形能力显著增强、受剪承载力降低;峰值荷载前沿竖向接缝两侧的相对变形将墙体分割为分缝剪力墙,提高了延性和耗能能力,降低了受剪承载力;竖向接缝处采用木板条补替部分混凝土可改善墙体的受力性能;按照强弯弱剪设计的墙体,水平接缝对墙体受力性能的影响可以忽略;装配式空心模板剪力墙的竖向接缝受力性能良好,可用于实际工程。     

Composite steel and concrete structural systems for seismic engineering

Research within the United States on seismic engineering of buildings using composite steel/concrete structural systems has increased dramatically in the past decade. This paper summarizes recent research on a number of these composite lateral resistance systems, including unbraced moment frames consisting of steel girders with concrete-filled steel tube (CFT) or steel reinforced concrete (SRC) columns; braced frames having concrete-filled steel tube columns; and a variety of composite and hybrid wall systems. The benefits of these structural systems relative to more common systems include their performance characteristics when subjected to service or ultimate loads, and their economy with respect both to material and construction. In addition, more in-depth research results will be presented on one of these composite systems, consisting of partially-restrained steel frames with composite reinforced concrete infill walls. The paper concludes with a summary of probable future design provisions for these composite systems.     

Performance of CFTST column to steel beam joints with blind bolts under cyclic loading

The objective of this research is to investigate the seismic performance of the composite joint consisting of square concrete filled thin-walled steel tubular (CFTST) column and steel beam with end plate and blind bolts. The cold-formed square tube in each CFTST column connection was fabricated by seam welding together four pieces of lipped angle with nominal wall thickness 1.5 mm or 3 mm. Four exterior joint specimens were tested under axially compressive load on the top of the columns and cyclic loads on the beam tip. The experimental parameters in the study were the thickness of the steel tube and the type of end plate. The seismic response of the blind bolted moment joints to CFTST columns was analyzed and evaluated in terms of the hysteretic behavior, failure modes, stiffness and strength degradation, ductility, and energy dissipation capacities of the joints. To improve the tension behavior of the blind bolted moment connections to the thin tube wall, the anchorage action of reinforcing rebar welded to the bolts with concrete-filled steel tubes was also investigated to consider the effect of cyclic loading. The experimental and analytical results indicated that when the end plate thickness is not less than 3 mm, the flush or extended end plate joints to CFTST columns exhibited large hysteretic loops and excellent seismic performance, such as ductility and energy dissipation capacity. The proposed innovative blind bolted joint was verified as a reliable and effective solution applied in mid- and low-rise buildings through properly design and detailing.     

钢-砌体组合墙梁结构在砌体结构房屋改造托换中的应用研究

针对砌体结构房屋加固改造中拆墙托换的问题,提出了一种新型的托换结构体系。首先对拟拆墙体上部采用外包角钢加固形成钢-砌体组合托梁,然后对上层墙体采用钢筋网聚合物砂浆面层进行加固,组合托梁与加固后的上层墙体形成组合墙梁结构,形成托换结构体系。通过对4个试件的试验研究得到:该托换结构的受力机理与砌体墙梁结构相同,可简化为拱结构,加固后的上层墙体通过拱作用将荷载向两端支座传递,角钢和钢筋网水平钢筋为拉杆,减小了组合托梁的内力,提高了构件的承载力。托梁端部和上层墙体端部均设置构造柱,保证了上层墙体内钢筋网水平钢筋的锚固,避免了托梁支座处砌体局压破坏。原墙体内是否有圈梁和角钢大小对托换结构的承载力有一定影响。该托换体系墙体最终产生斜压破坏,墙体的抗剪承载力可按照砌体墙梁墙体抗剪计算公式计算,但计算结果偏保守。     

华电集团华中总部基地结构设计

华电集团华中总部基地由主楼、裙楼、附楼和四层地下室组成,基础采用桩筏基础。地下室设计时,为了节约造价、提高使用空间,将外墙和支护的地下连续墙合二为一。地上建筑通过防震缝形成主楼、裙楼、附楼三个独立单元。主楼为"门"形复杂连体超限高层建筑,通过方案比选,采用了框架-核心筒混合结构方案,即钢筋混凝土核心筒+圆钢管混凝土柱+钢梁+加强层(伸臂及腰桁架)。主楼连体通过方案比选采用大网格巨型跨层钢桁架结构。为提高主楼两个塔楼抗侧刚度,对加强措施进行了分析,并采用了加强层、加密框柱等措施。对主楼结构布置、关键节点设计进行了研究;做了风洞试验并根据试验结果进行风荷载作用下结构响应的计算;对主楼舒适度、塔楼施工稳定性也进行了验算。结果满足设计要求,确保结构的安全性和适用性。     

装配式刚边框-冷弯薄壁型钢骨架组合墙体受力性能研究

冷弯薄壁型钢组合墙体主要由冷弯薄壁型钢骨架和外敷面板组成,结构轻巧,绿色环保,多用于中低层建筑,一般在施工现场拼装完成.为提升墙体的施工速度和安装效率,在墙体四周增设焊接刚性边框,提出一种新型装配式刚边框-冷弯薄壁型钢骨架组合墙体,该墙体在工厂预制完成,现场采用螺栓与周围构件连接.建立有限元模型分析面板类型、斜撑、螺钉...     

Experimental study on the seismic behavior of a shear wall with concrete‐filled steel tubular frames and a corrugated steel plate

Shear walls and core tubes in shear walls constitute the core anti‐earthquake vertical systems of high‐rise buildings. This paper proposes a new type of composite shear wall with concrete‐filled steel tubular frames and corrugated steel plates. The seismic behavior of the new shear wall is studied using a cyclic loading test and damage analysis. The failure mode, load‐carrying capacity, ductility, stiffness degradation, hysteresis behavior, and energy dissipating capacity exhibited in the test are studied. The test results show that when the proposed wall is broken, the tension side of concrete‐filled steel tubes is torn. The concrete at the bottom of the wall is detached and peels off along the through cracks. The energy dissipation capacity of concrete walls is more fully utilized. The proposed wall exhibits excellent deformability, energy dissipation capacity, and the stiffness degradation was slower than that of other walls. The use of corrugated steel plate significantly improved the seismic performance while simultaneously increasing the ductility and reducing the damage. In addition, this paper modified the energy dissipation factor in the Park & Ang model based on the situation of the specimen and experiment. It can be used to evaluate the damage degree of this new type of shear wall.     

风洞筒体预制板拼接节点力学性能试验研究

为满足大型风洞筒体预制板横向、纵向拼接处力学性能要求,提出了预制板横向、纵向拼接节点两种新型构造措施。对新型横向、纵向拼接节点各9个试件进行受弯、受剪和轴向拉压等试验研究,量测并分析试件的荷载、位移及应变,观测试件的裂缝发展情况和破坏过程。对新型横向拼接节点的受弯、受剪、受拉承载力以及纵向拼接节点的受剪承载力进行了理论简化分析计算,计算结果与试验结果吻合较好。研究结果表明:该新型横向、纵向拼接节点连接可靠,具有良好的承载能力和变形能力。