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.     

Studies on various structural system design options for twisted tall buildings and their performances

Employing twisted forms for tall buildings is a recent architectural phenomenon. This paper studies various structural system design options for twisted tall buildings and their performances based on lateral stiffness. Twisted tall buildings of various heights and rates of twist are designed with different types of contemporary tall building structural systems, such as diagrids, braced tubes and outrigger systems. The heights of the studied buildings range from 60 to 100 stories, and the rates of twist range from 0° to 3° per floor. As the rate of twist increases, the lateral stiffness of the tower decreases. The stiffness reduction rate caused by twisting is very much dependent upon the structural systems employed for twisted tall buildings. While an emphasis is placed on the structural performance of twisted tall buildings, other aspects, such as architectural and constructional issues, are also discussed holistically. Copyright © 2012 John Wiley & Sons, Ltd.     

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.     

Progressive collapse assessment of new hexagrid structural system for tall buildings

Hexagrid structure is an innovative tube‐type system. It is constructed with hexagonal exterior structural grids. The hexagrid works as an effective lateral and gravitational resisting system. This paper presents the progressive collapse‐resisting capacity of this new system and the common diagrid system based on the local failure of the structural elements in the story above the ground. The collapse behavior is evaluated by two different nonlinear static and dynamic analysis methods. This study was conducted to design two‐type 28‐story and 48‐story building models to withstand wind load for both structural systems. With the analytical results, the hexagrid has enough potential of force redistribution due to its special configuration. It is observed that the new system had high resistance to progressive collapse than diagrids in similar condition. The complementary studies illustrate that resisting progressive collapse capacity, in both hexagrid and diagrid structures, is increased by using the buckling‐restrained elements. The guidelines discussed here can help engineers to understand the mechanism of progressive collapse of the hexagrid structures. Copyright © 2013 John Wiley & Sons, Ltd.     

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.     

Vorogrid: A static-aware variable-density Voronoi mesh to design the tube structure tessellation of tall buildings

In the context of tall building design, the tube concept represents one of the most performing systems. The diagrid is the widespread type of tube system and consists of a diagonal grid of beams that wraps the building, forming a diamond pattern. It performs as lateral bracing and is additionally able to sustain vertical loading through axial forces. Despite its efficiency, a growing interest is recently observed in alternative geometries to replace the diagrid pattern and improve the architectural impact conferred by the building skin aesthetics on the urban environment. The paper pursues the use of a Voronoi mesh, in which the geometry of the cells is steered to known schemes for the structural design of a cantilever tube structure. The objective is to mimic a macroscopic structural behavior through a topology and size modification of the Voronoi mesh that increases the density for creating resisting paths with higher stiffness. The paper proposes a novel method Vorogrid for designing a new class of tall buildings equipped with an organic-looking and mechanically sound tube structure, which makes them a valuable alternative to competitors (diagrid, hexagrid, random Voronoi). Diagrids and hexagrids still remain more efficient in terms of forces and displacements but are characterized by a more usual appearance, instead Vorogrid offers more design control and better performances on average with respect to random Voronoi structures. This method is streamed into a pipeline that includes grid initialization strategies, geometric and structural optimization to mitigate the effects of the grid randomness, and structural sizing.     

智利地震钢筋混凝土高层建筑震害对我国高层结构设计的启示

2010年2月27日在南美洲智利发生的8.8级大地震,造成了钢筋混凝土高层建筑的严重破坏,这是近年来现代钢筋混凝土高层建筑经历的最大地震,引起了国内外工程设计人员的广泛关注.以智利高层建筑结构体系特点入手,分别介绍了智利地震中钢筋混凝土剪力墙高层建筑、立面收进复杂高层建筑、连体复杂高层建筑、带消能减震支撑超高层建筑、带...     

Progressive collapse behavior of rotor‐type diagrid buildings

In this study, the progressive collapse‐resisting capacities of axi‐symmetric or rotor‐type diagrid structural system buildings were evaluated based on arbitrary column removal scenario. For analysis models, 33‐story buildings with cylindrical, convex, concave and gourd shapes were designed, and their nonlinear static and dynamic analysis results were compared. The effect of design variables such as the number of total stories, slope of diagrids and the location of removed members was also investigated. According to the analysis results, the rotor‐type diagrid structures showed sufficient progressive collapse‐resisting capacity regardless of the differences in shapes when a couple of diagrids were removed from the first story. The design parameter such as building height and the slope of the diagrids did not affect the results significantly as long as they were designed to meet the current design code. Copyright © 2012 John Wiley & Sons, Ltd.     

Diagrid structural systems for tall buildings: Changing pattern configuration through topological assessments

Diagrid structural systems have been widely adopted for high‐rise buildings in the last decades, due to their structural efficiency and architectural potentials. The paper gives a comprehensive outline of the peculiarities of diagrids, providing a complete framework of their mechanical behaviour and investigates the accuracy of the assumptions used in common practice. The study explores, firstly, the effectiveness of the stiffness‐based methodology for optimal (69°) and nonoptimal (82°) diagonal inclinations, evaluating if the common approach leads to the definition of optimized cross sections in terms of reducing drifts and steel utilization. Subsequently, the paper analyses and compares diagrid models with non‐uniform pattern configuration generated from topological assessments. The authors test the contribution of a hybrid structure combining diagrid and outrigger systems to appraise whether a local increase in the pattern might be advantageous and preferable to a gradual stiffening from the top of the building toward the base.     

Book reviews

Whilst there have been numerous categorisations of high-rise buildings according to their function, architectural style, height or structural strategy, historically little work has been undertaken to classify them based on factors affecting their energy performance — their shape and form, façade, attitude to natural lighting, ventilation strategies, etc. These factors have been influenced by regulatory changes, developments in technology and materials, changes in architectural thinking and economic and commercial drivers. Developments such as the New York Zoning Law of 1916, the postwar innovations in curtain wall façades and the energy crises of the 1970s have all impacted on the way tall buildings of the time were designed and operated. These events also had a significant impact on the quantity of energy and the way in which it was consumed in tall buildings of the time. This paper examines the history of energy use in tall buildings, from their origins in North America in the late nineteenth century to the present day. In doing so, it categorises tall buildings into five chronological ‘generations’, based on their energy consumption characteristics.     

钢桁架筒结构基于刚度的设计方法——一种可持续的方法

桁架筒结构是高层建筑的一种高效的结构体系,该结构体系形式,自60年代末问世以来已广泛应用于大多数高层建筑中。提出基于刚度的设计方法,用以初步确定高层建筑桁架筒结构的构件尺寸。该方法适用于40～80层高的建筑物,并给出对应于代表性的设计荷载,使用材料最为经济的设计参数。就结构构件的不同几何配置对于设计经济性的影响进行了讨论,并对几何配置优化提出了建议。基于刚度的设计方法,只需较少迭代过程,非常适合于桁架筒结构的初步设计。对使用最少量的资源以满足构建建筑环境要求的设计,将具有推动和促进作用。     

高层建筑风激励振动控制Benchmark问题研究

从历届的国际结构控制大会中可以看出,高层建筑风激励振动控制问题一直是结构工程师致力讨论和研究的重点课题.本文通过对风激励高层建筑模型进行自由度缩减和降阶处理,得到大大简化的评估模型.运用不同的控制方法和控制策略对基准问题高层建筑在脉动风荷载作用下的位移、速度和加速度响应量进行分析,提出基于随机分析的均方根响应和基于确定...     

我国高层建筑钢结构发展的主要问题

本文概述了我国目前高层钢结构建筑现状，指出了我国高层钢结构发展的三大问题，即：国产化问题、综合效益问题和结构设计问题。本文论述了我国高层钢结构国产化已具备的条件，分析了高层建筑各部分投资比例及采用钢结构在经济性能和结构性能上的优势，讨论了目前我国高层钢结构设计存在的主要问题。     

Experimental testing of tall reinforced masonry walls under out-of-plane actions

This paper presents the results of experimental tests on tall reinforced masonry walls. Systems made with vertically perforated clay units for building mainly tall, load-bearing, reinforced masonry walls for commercial and industrial purposes were studied for applications in areas characterised by low to high seismic risk. Tests aimed at obtaining basic mechanical characterisation of the construction systems, and reproducing the behaviour of single-storey reinforced masonry buildings provided with deformable roofs. For this structural configuration, a special set-up for out-of-plane cyclic tests was designed and built. In particular, this paper presents: (a) systems used for tall reinforced masonry wall construction; (b) test set-up to reproduce the behaviour under out-of-plane loads and P–Δ effects; (c) experimental results obtained. The final aim is validating the effectiveness of the proposed construction systems and achieving complete mechanical characterisation for modelling and structural assessment purposes.     

Efficient structural analysis of wall–frame structures

In this study, an efficient analytical model for the dynamic analysis of tall buildings with a shear wall–frame structural system has been proposed. A shear wall–frame structural system usually consists of a core wall showing flexural behavior and a frame presenting shear behavior. Therefore, the deformed shape of the shear wall–frame structural system is shown by the combination of flexural mode and shear mode. To consider this characteristic in developing an efficient analytical model, the effect of shear wall and frame on the dynamic behavior of a tall building with a dual system has been separately investigated. In order to consider the effect of the shear wall in the frame model without shear wall, a rigid body was used instead of the shear wall. Each equivalent model for the separated shear wall part and frame part has been independently developed, and two equivalent models were then combined to create an efficient analytical model for tall buildings with a shear wall–frame structural system. In order to verify the efficiency and accuracy of the proposed method, time history analyses of tall buildings with a shear wall–frame system were performed. With analytical results, it has been confirmed that the proposed method can provide accurate results with significantly reduced computational time and memory. Copyright © 2013 John Wiley & Sons, Ltd.     

Case study of the dynamic response of a medium-height building to wind-gust loading

Increasing attention has been paid in recent years to the criterion of perception by the occupants of tall buildings of motion caused by high winds. Attention has, however, been focused on very tall buildings, predominantly in North America. This paper presents the results of observations of wind-induced motion of a building of relatively modest size, and of accompanying studies including the use of a mechanical shaker.

The investigation confirmed that perceptible motions were to be expected rather frequently, although the building in question was found to have rather better than average values of the relevant dynamic structural properties. A conventional stochastoc model of excitation by gusts appeared to be adequate for prediction to the relatively coarse precision which is acceptable for this purpose. The high response levels were primarily a result of the exposure of the site. The implications for designers are discussed.     

Mode shape linearization and correction in coupled dynamic analysis of wind‐excited tall buildings

The three‐dimensional mode shapes found in modern tall buildings complicate the use of the high‐frequency base balance (HFBB) technique in wind tunnel testing for predicting their wind‐induced loads and effects. The linearized‐mode‐shape (LMS) method was recently proposed to address some of the complications in the calculation of the generalized wind forces, which serve as the input to modal analysis for predicting wind‐induced dynamic responses of tall buildings. An improved LMS method, called the advanced linearized‐mode‐shape (ALMS) method, is developed in this paper by introducing torsional mode shape corrections to account for the partial correlation of torques over building height. The ALMS method has been incorporated into the accurate complete quadratic combination method in the coupled dynamic analysis to form a comprehensive procedure for the determination of equivalent static wind loads (ESWLs) for structural design of complex tall buildings. The improved accuracy in the prediction of generalized forces by the ALMS method has been validated by a 60‐storey benchmark building with multiple‐point simultaneous pressure measurements. A practical 40‐storey residential building with significant swaying and torsional effects is presented to demonstrate the effectiveness of the proposed wind load and response analysis procedure based on the HFBB data. Copyright © 2010 John Wiley & Sons, Ltd.     

Continuous transfer beams supporting in-plane loaded shear walls in tall buildings

The failure mechanism and structural behavior of transfer beams supporting in-plane loaded shear walls have received added emphasis owing to their importance in connection with tall building construction. This paper presents an analysis of and investigation of the structural behavior of two-span transfer beam-shear wall systems in tall buildings. The interaction between the transfer girders and the shear wall has been investigated considering interior and exterior column interaction effects. The upper structural form has a significant effect on the failure mechanism of the transfer girders, which can act as full tension members or behave as ordinary flexural beams. Stress distributions in the shear wall interactive zone are presented. The relevant parameters that significantly influence the force transfer mechanism and structural behavior, such as the span/depth ratio of the transfer beam, the span of the shear wall and the stiffness of the support columns, are highlighted. The present paper provides a very useful reference for the design of continuous transfer girders supporting in-plane loaded shear walls in tall buildings.     

在高层建筑结构设计课程中引入工程哲学思想的探讨

高层建筑涉及诸多的学科和专业领域,具有复杂、跨专业的体系,并具有显著的社会性特征。土木工程本科专业以培养工程技术人才为主要目标,为培养复合型土木工程人才,有必要将工程哲学思想引入高层建筑结构设计课程。将工程系统观、工程社会观和工程伦理观等思想和理念与高层建筑结构设计课程相结合,培养学生以全局、系统的方式和观点思考高层建筑结构设计方法,并在社会层面上处理高层建筑结构设计中的问题。     

高层混凝土结构重力二阶效应的影响分析

传统的高层混凝土结构重力二阶效应分析大多是近似方法,对于实际高层结构,这种近似分析方法会带来较大差错。本文通过在单元几何方程中引入二次项,较为精确地考虑了重力二阶效应对高层结构受力特性的影响。根据高层结构的特点,建立了梁柱单元、单片墙单元和筒体墙单元三种非线性宏观单元,并编制了三维推覆分析程序。单元截面分析采用高斯数值积分方法,可对任意不规则截面进行分析,在非线性方程组的求解算法中引入了弧长算法,能够搜索到结构反应的全过程。对两栋不同结构体系的高层混凝土建筑进行了推覆分析,详细讨论了二阶效应对结构顶点侧移和基底倾覆力矩的影响。研究结果表明:对高度100m左右的高层混凝土结构,多遇地震作用下的强度和变形验算可不考虑重力二阶效应的影响,罕遇地震作用下的弹塑性变形验算一般应考虑重力二阶效应的影响。