Proposing the hexagrid system as a new structural system for tall buildings

In order to improve the efficiency of tube‐type structures in tall buildings, a new structural system, called hexagrid, is introduced in this paper. In comparison with diagrid system, it consists of multiple hexagonal grids on the face of the building. In this research, a set of structures using diagrid system having four various diagonal angles and hexagrid system were designed on a strength and stiffness‐based approach for buildings with 30, 50, 70 and 90 stories to withstand wind load. The impact of different geometric configurations of structural members on the maximum lateral displacement and architectural performance in both diagrid and hexagrid systems is compared. The stiffness sensitivity using a similar interior bracing system in both systems is also discussed. In this study, the seismic performance of a 30‐story diagrid structure and a hexagrid structure was evaluated using nonlinear static and dynamic analyses. According to the results, the hexagrid system has a better architectural view and more ductility and stiffness sensitivity, which are about three times than that of the diagrid system. And finally, in comparison with the diagrid system, the hexagrid system has enough potential to push the height limit. The guidelines discussed here are for architectural and structural engineers to improve freehand design. Copyright © 2012 John Wiley & Sons, Ltd.     

Diagrid: An innovative,sustainable, and efficient structural system

In recent years, diagrid structures have received increasing attention among both designers and researchers of tall buildings for creating one‐of‐a‐kind signature structures. This paper presents a state‐of‐the‐art review of diagrid structures. First, various diagrid configurations, main factors affecting their behaviors, and related design parameters and approaches are discussed. Then, diagrid applications for free‐form steel and concrete structures are introduced showing the diagrid applicability for complex structures followed by recent advances in structural design of diagrid connections, diagrid nonlinear behavior, and structural control of diagrids. Recent studies about a new variation of tubular and diagrid systems, hexagrids, are discussed briefly. Finally, the diagrid potential in design of sustainable buildings is delineated.     

钢管混凝土柱中的新型钢截面

在现代工程建设中,钢管混凝土（CFT）柱已逐渐成为高层建筑、桥梁等结构系统中的核心构件。在钢管混凝土的承载能力分析中有效参数有：钢与混凝土之间的粘结、钢管局部屈曲强度、混凝土徐变和连接处柱的负荷状态。考虑到这些有效参数,提议一种新截面,可用于高层建筑及大跨度桥梁。所提议钢截面的主要特点是内部纵向对称加劲肋。对此种截面（圆形和八角形）和钢管混凝土柱的常用截面进行轴向和循环荷载作用下的对比分析。同时采用有限元建模进行多种不同的分析。结果表明：新型截面在轴向和循环荷载下的强度和延性均有所增强,因此建议在施工中可采用此种截面。     

斜交网格筒-核心筒结构地震非线性性能研究

斜交网格筒新型结构体系具有较大的侧向刚度,为建造高层、超高层结构提供了有利条件。然而目前该类型结构的地震非线性性能尚未被明确掌握,导致在结构设计中面临体系构件屈服顺序不明确、外网筒斜柱受力和屈服机制不清楚、外网筒地震失效路径不清晰等关键性抗震问题。通过对典型高层斜交网格筒-核心筒结构地震非线性有限元分析和典型模块子结构的拟静力试验研究,针对该类型体系构件的屈服顺序、斜柱受力和屈服机制以及外网筒的地震失效路径等进行系统研究,明确了该类型体系的上述地震非线性性能。     

变截面钢管混凝土格构柱抗震性能试验研究

为研究变截面钢管混凝土格构柱的抗震性能,以缀管布置形式和柱肢倾斜度为试验参数,对7根变截面钢管混凝土格构柱进行了水平低周反复荷载试验,分析了该类柱的破坏模式、滞回曲线、骨架曲线、延性、耗能、承载力退化、刚度退化和变形恢复等。研究结果表明：变截面钢管混凝土格构柱试件的破坏形态基本相同,均为整体压弯破坏;滞回曲线较饱满无明显捏缩,具有良好的抗震性能;随着柱肢倾斜度的增大,格构柱的水平承载力和耗能能力有一定程度提高,刚度退化率略有增加。缀管布置形式对格构柱位移延性的影响较大;与平缀管式钢管混凝土格构柱相比,斜缀管式钢管混凝土格构柱的初始刚度和水平峰值荷载明显增大,耗能能力略有降低,承载力退化更为明显。     

A novel steel section for concrete-filled tubular columns

In modern structural constructions, concrete-filled steel tubular (CFT) columns have gradually become a central element in structural systems like tall buildings, bridges and so forth. The effective parameters on load carrying capacity of CFT columns are the bond between the steel and internal concrete, local buckling strength of steel tube, creep of concrete and loading conditions of column at connections. Considering these effective parameters, a novel section is suggested which can be used for columns of tall buildings and bridges with large spans. The main characteristic of the suggested steel section is internal longitudinal symmetric stiffeners. In the present study, a comparative investigation into the behavior of this novel section (with circular and octagonal shapes) and the most common used sections of CFT columns has been carried out under axial and cyclic loading. Having verified the finite element modeling, several different analyses have been undertaken. The results of the analyses clearly exhibit the increase in strength and ductility of the suggested novel section under axial and cyclic loading and therefore, its application is recommended in construction practice.     

复杂高层建筑抗震与消能减震研究进展

复杂高层建筑的震害在近来的历次地震中都有发生,其抗震分析和设计难度较大,提高其抗震性能是当前建筑抗震的难点之一。通过对近10年来国内在复杂高层建筑抗震方面的研究进行回顾和总结,重点介绍了组合剪力墙及筒体结构、钢管混凝土结构、结构模型振动台试验和三种消能减震方法。提出了采用新型高效的结构体系及高性能抗震部件或消能减震新技术改善复杂高层建筑抗震性能。这些研究工作与工程实践紧密结合,大部分研究成果已在实际工程中成功应用。图18参28     

轴向压力下钢管混凝土交叉连接的性能——试验研究

在新型斜肋构架结构体系中,一般的连接有4个斜向柱和几个水平梁。提出两种钢管混凝土交叉连接,可以应用钢管混凝土斜肋直接安装在结构梁上。基于中国的钢管混凝土的规范提出了这种连接的承载力计算方法。完成了8个连接在轴压荷载下的各种性能、承载力及破坏机理。试验中考虑的变量包括连接细节、柱间斜角及荷载形式,得到试件的挠度、应力、破坏模式和承载力。研究结果显示:CFST柱构件之间的连接角度对其破坏模式具有很大影响,此外,连接板比翼板更具有约束作用,荷载类型对连接性能的影响很小。受压承载力与计算值的比在0·99到1·31,说明计算承载力是精确的,对于结构设计是偏于安全的。最后,验证了所提出的连接性能与钢管混凝土短柱相似。     

T形钢管混凝土柱-钢梁平面框架抗震性能研究

为研究T形钢管混凝土柱-钢梁框架抗震性能,进行了两榀T形钢管混凝土柱-钢梁平面框架拟静力试验,探讨了柱轴压比对框架滞回性能的影响。试验结果表明,框架在往复荷载作用下均呈理想的梁铰破坏机制;随着水平位移荷载的增大,框架滞回曲线渐趋饱满,最终框架正负向位移延性系数均大于4.0,满足建筑结构抗震延性需求;随着柱轴压比增大,其耗能能力提高,但框架的延性下降。提出了该类框架的简化三折线恢复力模型,可为T形钢管混凝土柱-钢梁框架的深化研究及工程设计提供参考。     

试议高层钢管混凝土柱的推广前景

通过钢管混凝土柱与其它位结构形式的比较，说明钢管混凝土柱的优越性，同时论述它在高层建筑中的广泛适应性和发展前景．     

高层钢-混凝土混合结构弹塑性地震位移的工程实用计算

本文针对目前高层建筑中常用的外钢框架-内混凝土核心筒混合结构体系的弹塑性地震位移的实用计算开展研究。在合理选取一定数量的地震记录及典型的结构形式的基础上,采用经实验检验的分析模型与计算程序,得到了钢-混凝土混合结构的弹塑性层间相对位移与主要结构参数之间的大致规律,并通过统计分析,得到了混合结构的弹塑性层间相对位移与各参数的定量关系,以此提出了进行罕遇地震下高层钢-混凝土混合结构弹塑性位移验算时的计算数表。     

#br# 偏压荷载下钢管混凝土柱的抗扭性能试验研究

自重和水平地震作用将对曲线梁桥中墩梁固结的墩柱和拱桥钢管混凝土结构的主拱产生偏压和扭转复合效应。为研究钢管混凝土柱在偏压荷载作用下的抗扭性能,完成了8个不同截面形状钢管混凝土柱试件单调纯扭加载、往复纯扭加载和偏压-往复扭转加载拟静力试验。试验结果表明：钢管混凝土柱在往复扭转作用下的滞回曲线较为饱满,没有“捏拢”现象产生,试件的强度和刚度的损伤退化程度较低,具有较好的耗能能力。矮柱试件破坏现象较高柱试件更为明显,矮柱试件的屈服转角小于高柱,屈服扭矩与高柱相差不大,极限承载力大于高柱,极限转角小于高柱,耗能能力比高柱更好。偏压-往复扭转荷载作用下的方形截面试件刚度退化较为明显,偏压作用导致方钢管混凝土柱试件耗能能力降低。极限状态下,偏压作用改变了钢管的褶皱角度。     

Study on seismic performance of a super‐tall steel–concrete hybrid structure

Many steel–concrete hybrid buildings have been built in China. The seismic performance of such hybrid system is much more complicated than that of steel structure or reinforced concrete (RC) structure. A steel–concrete hybrid frame‐tube super‐tall building structure with new type of shear walls to be built in a district of seismic intensity 8 in China was studied for its structural complexity and irregularity. Both model test and numerical simulation were applied to obtain the detailed knowledge of seismic performance for this structure. First, a 1/30 scaled model structure was tested on the shaking table under different levels of earthquakes. The failure process and mechanism of the model structure are presented here. Nonlinear time‐history analysis of the prototype structure was then conducted by using the software PERFORM‐3D. The dynamic characteristics, inter‐story drift ratios and energy dissipation conditions are introduced. On the basis of the comparison between the deformation demand and capacity of main structural components at individual performance level under different earthquake level, the seismic performance at the member level was also evaluated. Despite the structural complexity and code‐exceeding height, both experimental and analytical results indicate that the overall seismic performance of the structure meet the requirements of the Chinese design code. Copyright © 2012 John Wiley & Sons, Ltd.     

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。     

Nonlinear behavior of composite shear walls with vertical steel encased profiles

Research on seismic engineering of buildings using composite steel-concrete structural systems has increased in the past decade. One horizontal resisting system for buildings, placed in seismic areas, is the composite steel-concrete structural shear wall with steel encased profiles (CSRCW). The benefits of this structural system, relative to more common systems, include the performance characteristics when subjected to service or ultimate loads. The present paper summarizes the experimental results of recent research made on six experimental steel-concrete composite elements 1:3 scale, tested in laboratory under cyclic lateral loads. The experimental elements differ by the arrangement of the steel shapes embedded in the cross section of the wall and by the cross section type of the steel encased profiles. All specimens were tested under constant vertical load and cyclically increasing horizontal (lateral) loads. The tests were performed until failure. Using the recorded data during the tests, the following parameters are presented and discussed: maximum load capacity, stress and strain distribution in structural components (reinforcements, structural steel and on concrete surface), interstory drifts, cracking patterns, deformation and degradation capacity.     

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。     

薄壁方钢管再生混合柱抗震性能试验研究

通过15根薄壁方钢管再生混合柱在定常轴力和水平往复荷载作用下的拟静力试验,研究了废弃混凝土取代率、钢管壁厚、轴压比等参数对试件抗震性能的影响。基于新、旧混凝土的组合强度,根据国内外钢管混凝土结构的设计标准以及基于ABAQUS的纤维梁单元模型,对试件的水平承载力进行了计算分析。研究表明：废弃混凝土取代率在0~40%之间变化对试件的初始抗侧刚度、钢管局部屈曲、破坏位移、负刚度段行为、等效黏滞阻尼系数、滞回曲线形状影响有限,但再生混合柱的水平承载力总体上比全现浇柱有所降低;当钢管壁厚在1.78~5.50mm之间变化时,随钢管壁厚增加试件并未表现出更好的变形能力;在钢管壁厚仅1.78 mm（宽厚比168.5）的情况下,轴压比0.4的再生混合柱的破坏位移角可达1/35,满足我国现行抗震规范的层间位移角限值要求;采用5部现行标准计算薄壁方钢管再生混合柱的水平承载力可获得与同条件全现浇柱相当的安全性;横截面积和用钢量相同时,薄壁方钢管再生混合柱的抗震性能优于钢筋混凝土柱。研究发现,薄壁方钢管再生混合柱应用于中、低轴压比（实际轴压比小于0.4）的情况是可行的。     

Diagrid structures for tall buildings: case studies and design considerations

The originality of form is one of the new trends that can be identified in the current design of tall buildings. In this design trend, the so‐called diagrid structures, which represent the latest mutation of tubular structures, play a major role due to their inherent esthetic quality, structural efficiency and geometrical versatility. In this paper, an overview on application of such typology to high‐rise buildings is carried out; in particular, in the first part of the paper, the peculiarities of diagrid systems are described: starting from the analysis of the internal forces arising in the single diagrid module due to vertical and horizontal loads, the resisting mechanism of diagrid buildings under gravity and wind loads is described, and recent researches and studies dealing with the effect of geometry on the structural behavior are discussed. In the second part of the paper, a comparative analysis of the structural performance of some recent diagrid tall buildings, characterized by different number of stories and different geometries, namely the Swiss Re building in London, the Hearst Headquarters in New York and the West Tower in Guangzhou, is carried out, and some general design remarks are derived. Copyright © 2012 John Wiley & Sons, Ltd.     

Research on structural design of a super highrise building in Qatar

Designed by John Novel, the super highrise office building in Doha adopts the exterior net tube composed of R.C. crossing diagrid columns and floor ring beams as the main structure. After examining the concrete creep effects, the loading, the construction sequence, the partially prestressing of ring beams, the progressive failure of the diagrid columns, the bearing capacity of diagrid column nodes, the temperature and shrinkage effects, the buckling of the diagrid column and the whole structure, some important incipient faults regarding structural safety in tender design were found. These faults include insufficient bearing capacity of the cross nodes, and the building inclination due to the differential shortening of the diagrid columns from concrete creep. Several effective technical improvements were employed to ensure the safety of the building, such as adopting hollow sections for the diagrid columns in the lower stories at the north side, the strengthening of the cross nodes of the diagrid columns by introducing steel benches, and decreasing the prestressing ratio in ring beams.     

高层建筑斜交网格筒体结构分析与研究

斜交网格筒体结构体系是一种新颖的结构形式,可以实现建筑立面的多样性,同时,该体系在受力方面也具有一些与传统框筒体系不同的特点。本文采用标准算例,详细比较了斜交网格筒体结构体系与密柱深梁框筒结构体系在重力荷载、水平荷载作用下的差异,说明了斜交网格筒体结构在应用于高层建筑结构设计中,需要注意的一些关键问题,从而为进一步推广该体系的应用提供参考。