Drift design of steel‐frame shear‐wall systems for tall buildings

Drift design methods based on resizing algorithms are presented to control lateral displacements of steel‐frame shear‐wall systems for tall buildings. Three algorithms for resizing of structural members of the steel‐frame shear‐wall systems are derived by formulating the drift design process into an optimization problem that minimizes lateral displacement of the system without changing the weight of a structure. During the drift design process, cost‐effective displacement participation factors obtained by the energy method are used to determine the amount of material to be modified instead of calculating sensitivity coefficients. The overall structural design model with the drift design method for the steel‐frame shear‐wall systems is proposed and applied to the structural design of three examples. As demonstrated in the examples, the lateral displacement and interstorey drift of a frame shear‐wall system can be effectively designed by the drift design method without the time‐consuming trial‐and‐error process. Copyright © 2002 John Wiley & Sons, Ltd.     

Structural design of high‐rise buildings using steel‐framed modules: A case study in Hong Kong

Steel‐framed modular buildings afford certain advantages, such as rapid and high‐quality construction. However, although steel‐framed modules have been adopted in several countries, most of them are limited to low‐to‐medium‐rise structures; modular high‐rise buildings are rare. This study proposes a feasible structural design solution for high‐rise buildings using a steel‐framed modular system. A 31‐story student hostel building in Hong Kong is redesigned as a steel‐framed modular building and used as a case study. The finite element models of the building are formulated, and the structural behaviors under wind and earthquake load scenarios are compared. Moreover, the structural design process used for the 31‐story building is applied to design a hypothetical 40‐story modular building to further examine the proposed design solution. The numerical analysis results indicate that the roof lateral displacements and interstory drift ratios of the redesigned modular building are within the allowable limits of design codes; moreover, the modular connections behave elastically under the most adverse loading scenarios. Accordingly, the proposed solution can be used to design steel‐framed modular buildings of up to 40 stories, while complying with relevant wind and seismic codes.     

DRIFT CONTROL OF HIGH-RISE BUILDINGS WITH UNIT LOAD METHOD

The use of displacement participation factors obtained by the unit load method provides an effective drift control tool for high-rise buildings. Structural sensitivity coefficients and displacement participation factors for members in a structure with respect to the lateral displacement to be controlled are computed and used for identifying active members and their corresponding displacement components. The drift control method using the displacement participation factors with a variable linking strategy is formulated into an optimization problem to determine the amount of material to be modified. Using the drift control method, a structural design model for a high-rise building is proposed and applied to one verifying example and two moment resisting frames. Time consuming trial-and-error processes related to the structural design of a high-rise building is avoided by the proposed structural design model. As demonstrated in the examples, the maximum lateral displacements of the examples are reduced by 57·05, 40·0 and 16·36% without changing the total weights of the structures. © 1997 John Wiley & Sons, Ltd.     

Wind‐induced inter‐story drift analysis and equivalent static wind load for multiple targets of tall buildings

In super high‐rise buildings with varying story heights, the wind‐induced inter‐story drifts might violate the specified limit. However, these effects have seldom been concerned in wind‐induced response analysis. The theory and application of equivalent static wind load (ESWL) for wind‐induced inter‐story drifts of super high‐rise buildings were studied in this paper. A spectral decomposition method suitable for multi‐point excitation problems was firstly proposed. The formula of ESWL targeting for largest inter‐story drift was derived. For more reasonable structural design, the ESWL for multiple targets including displacement atop of building and inter‐story drifts at all story levels is put forward, in which the dominant modal inertial forces are adopted as the based load vectors. The presented methods were finally verified by its application for the wind‐induced response analysis for a tallest super tall building in Guangzhou. The researched results showed that the proposed spectral decomposition method not only has the same precision as the complete quadratic combination method but also possesses higher computation efficiency. The ESWL for multiple targets produces the same static responses for all the specified wind‐induced response, so it is much more rational for wind‐resistant structural design. Meanwhile, it is more reasonable to select the wind‐induced responses in the same direction simultaneously as the targeted values for obtaining the required ESWLs; however, the ESWL targeting for the wind‐induced responses in all degrees of freedom would generate more queer and unrealistic ESWLs distribution. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimal drift design model for multi‐story buildings subjected to dynamic lateral forces

An optimal drift design model for a linear multi‐story building structure under dynamic lateral forces is presented. The drift design model is formulated into a minimum weight design problem subjected to constraints on stresses, the displacement at the top of a building, and inter‐story drift. The optimal drift design model consists of three main components: an optimizer, a response spectrum analysis module, and a sensitivity analysis module. Using a small example, the validation of the proposed model has been tested by a comparison of optimal solutions. Then, the performance of the optimal drift design model is demonstrated by application to three steel frame structures including a 40‐story building. Various structural responses including lateral displacement and inter‐story drift distributions along the height of the structure at the initial and final design stages are presented in figures and tables. Time‐consuming trial‐and‐error processes related to drift control of a tall building subjected to lateral loads is avoided by the proposed optimal drift design method. Copyright © 2003 John Wiley & Sons, Ltd.     

钢筋混凝土超高层建筑层间位移的模型试验研究

通过 11层框架 剪力墙平面截断模型的静力加载试验 ,研究了原型为 5 2层的钢筋混凝土超高层建筑在正常使用状态下的受力和变形 ,重点考察了层间位移与构件裂缝的关系 ,同时研究了竖向荷载及加强层对层间位移限值的影响。试验结果表明 ,正常使用状态下将钢筋混凝土超高层建筑的层间位移角控制在 1/ 5 0 0以内时 ,其竖向构件不会开裂 ,框架梁、连梁与填充墙的裂缝均可以控制在允许范围内。现行《高规》的层间位移限值可以放松     

Application of GPS to monitoring of wind‐induced responses of high‐rise buildings

A new monitoring system using GPS is introduced to measure wind‐induced responses of high‐rise buildings. In this paper, wind‐induced responses of a long‐period structure include relative lateral displacements, acceleration records, and torsional displacements at the top of a building. After comparing responses of a test model measured by GPS with responses obtained by the most commonly used laser displacement meters and accelerometers, the wind‐induced responses of a 66‐story high‐rise building subject to the yellow dust storm were measured by the GPS‐based monitoring system. Based on the field measurement, it is concluded that the complete motion history of a high‐rise building can be monitored by GPS. Copyright © 2007 John Wiley & Sons, Ltd.     

Robustness of base‐isolated high‐rise buildings under code‐specified ground motions

The robustness of base‐isolated high‐rise buildings is investigated under code‐specified ground motions. Friction‐type bearings are often used in base‐isolated high‐rise buildings to make the natural period of those buildings much longer. While additional damping can be incorporated into every story in passive controlled structures with inter‐story type passive members, that can be incorporated into the base‐isolation story only in the base‐isolated building. This fact leads to the property that, as the number of stories of the building becomes larger, the damping ratio reduces. This characteristic may cause some issues in the evaluation of robustness of base‐isolated high‐rise buildings. The purpose of this paper is to reveal the robustness of base‐isolated high‐rise buildings. A kind of inverse problem for the target drift in the base‐isolation story is formulated in order to determine the required quantity of additional viscous damping. It is demonstrated numerically that, as the base‐isolated building becomes taller, the damping ratio becomes smaller and the ratio of the friction‐type bearings in the total damping becomes larger. This may lead to the conclusion that base‐isolated high‐rise buildings have smaller robustness than base‐isolated low‐rise buildings. Copyright © 2007 John Wiley & Sons, Ltd.     

竖向不规则结构非线性静力推覆分析的水平侧向力研究

非线性静力分析方法可以较为简便地预估结构的弹塑性反应,但仅取常见水平侧向力分布模型并不能满足实际工程的需要,例如高振型的影响和不规则结构的特殊性。对竖向不规则结构进行非线性时程分析,建立了水平侧向力分布与结构层刚度的关系式,从而提出了一种新的水平侧向力分布形式和方法。结合几种常见的水平侧向力形式,对5种侧向刚度不规则的情况进行了推覆分析,并与时程分析结果进行了比较,结果表明该方法不但可以找到各种侧向刚度不规则结构的薄弱层而且还具有较高的精度。     

Analysis of outrigger numbers and locations in outrigger braced structures using a multiobjective genetic algorithm

Due to its advantages, the outrigger braced system has been employed in high‐rise structures for the last 3 decades. It is evident that the numbers and locations of outriggers in this system have a crucial impact on the performance of high‐rise buildings. In this paper, a multiobjective genetic algorithm (MGA) is applied to an existing mathematical model of outrigger braced structures and a practical project to achieve Pareto optimal solutions, which treat the top drift and core base moment of a high‐rise building as 2 trade‐off objective functions. MATLAB was employed to explore a multiobjective automatic optimization procedure for the optimal design of outrigger numbers and locations under wind load. In this research, various schemes for the preliminary stages of design can be obtained using MGA. This allows designers and clients easily to compare the performance of structural systems with different numbers of outriggers in different locations. In addition, design results based on MGA offer many other benefits, such as diversity, flexible options for designers, and active client participation.     

高层建筑结构位移控制研讨

介绍了世界各国规范对高层建筑结构设计位移控制的规定,论述了高层建筑顶点位移、层位移差、层间位移等的相互关系,特别是明确了层位移差与受力层间位移的区别,在此基础上,结合有关科研成果及工程设计经验,对高层建筑结构位移限值的规定提出了一些建议,可供修订规范及设计时参考.     

Effect of vertical structural irregularity on seismic design of tall buildings

Many tall buildings are practically irregular as an entirely regular high‐rise building rarely exists. This study is thus devoted to assessing the approach and coefficients used in the seismic design of real‐life tall buildings with different vertical irregularity features. Five 50‐story buildings are selected and designed using finite element models and international building codes to represent the most common vertical irregularities of reinforced concrete tall buildings in regions of medium seismicity. Detailed fiber‐based simulation models are developed to assess the seismic response of the five benchmark buildings under the effect of 40 earthquake records representing far‐field and near‐source seismic scenarios. The results obtained from a large number of inelastic pushover and incremental dynamic analyses provide insights into the local and global seismic response of the reference structures and confirm the inferior local response of tall buildings with severe vertical irregularities. Due to the significant impacts of the severe irregularity types on the seismic response of tall buildings, the conservative code approach and coefficients are recommended for design. It is also concluded that although the design coefficients of buildings with moderate irregularities are adequately conservative, they can be revised to arrive at more consistent safety margins and cost‐effective designs.     

Optimal compensation of differential column shortening in high‐rise buildings

To avoid unexpected damage in structural and nonstructural elements, differential shortening between vertical members resulting from differing stress levels, loading histories, volume‐to‐surface ratios and other factors in a high‐rise building must be properly considered in the design process. While research activity has been reported in the literature on the development of estimation algorithms or prediction procedures for the elastic and inelastic shortenings of vertical members, no algorithms or systematic methods for the compensation of the differential shortenings have been reported. In this paper, a compensation method for the differential column shortening in a high‐rise building is formulated into an optimization problem. A simulated annealing algorithm is used to find optimal solutions. The proposed method is applied to the compensation of the differential shortening of the vertical members in two high‐rise buildings, including one verifying example of a 70‐storey building and a practical example of a 63‐storey building. As demonstrated in the examples, the differential shortenings of the examples are effectively controlled by the optimal compensation method. Copyright © 2003 John Wiley & Sons, Ltd.     

Integrated wind‐induced response analysis and design optimization of tall steel buildings using Micro‐GA

This paper presents an integrated procedure for wind‐induced response analysis and design optimization for rectangular steel tall buildings based on the random vibration theory and automatic least cost design optimization technique using Micro‐Genetic Algorithm (GA). The developed approach can predict wind‐induced drift and acceleration responses for serviceability design of a tall building; the technique can also provide an optimal resizing design of the building under wind loads to achieve cost‐efficient design. The empirical formulas of wind force spectra obtained from simultaneous measurements of surface pressures on various rectangular tall building models in wind tunnel tests are verified testified using a published example. Upon the known wind force spectra, the equivalent static wind loads for every storey, such as along‐wind, across‐wind and torsional loads, are then determined and applied for structural analysis including estimation of wind‐induced responses. An improved form of GAs, a Micro‐GA, is adopted to minimize the structural cost/weight of steel buildings subject to top acceleration and lateral drifts constraints with respect to the discrete design variables of steel section sizes. The application and effectiveness of the developed integrated wind‐induced response analysis and design optimization procedure is illustrated through a 30‐storey rectangular steel building example. Copyright © 2009 John Wiley & Sons, Ltd.     

An inter‐story drift‐based parameter analysis of the optimal location of outriggers in tall buildings

Outriggers are usually added in structural systems of tall buildings to collaborate central shear walls with peripheral columns. With outriggers, the structural overturning moment can be balanced, and the inter‐story drift can be controlled under horizontal loads. Therefore, the optimal location of outriggers plays a very important role in controlling the behavior of the whole building. Existing research has focused on the optimal position of outriggers on the base of the structural roof deflection. In the engineering practice, however, inter‐story drift is the most important target to control the design of tall building structures. This paper investigates the theoretical method of inter‐story drift‐based optimal location of outriggers. A Matlab program is written to perform the parameter analysis of optimal location of outriggers. Take a 240‐m tall building for a target building, the optimal location of one to three sets of outriggers under wind and earthquakes is obtained and can be utilized for the structural preliminary design of tall buildings. Copyright © 2015 John Wiley & Sons, Ltd.     

钢筋混凝土超高层建筑层间位移限值的探讨

高层建筑结构设计中层间位移值是一个重要的参数,但是对于超高层建筑目前还无规范可以遵循。本文通过对层间位移组成的分析,提出了设计建议值供大家讨论。     

The use of single diagonal bracing in improvement of the lateral response of tall buildings

The improvement of the lateral response of tall buildings is a subject of great concern both in high wind areas and seismic regions. The lateral deflection of a tall building subjected to lateral loads can be decomposed into shear and bending components. Properly oriented single diagonal bracings are introduced in order to bring advantageous interactions between these two modes of deflection resulting in a reduction of the overall lateral deflection of the frame. The deflection of a panel with a single diagonal, when subjected to vertical downward load, has a lateral component caused by the axial force developed in the single brace, which, due to asymmetry, results in the lateral deflection. In order to restrict the panel from lateral deflection a compensating lateral force is required. By locating the single diagonal bracings in an improved manner, the vertical tension and compression on the opposite sides of the frame caused by the bending effect automatically generate the above mentioned lateral compensating force which opposes the inter story drift. A simple truss model is introduced to study the relationship between the vertical loading and the lateral load required to retain the vertical alignment of a panel with a single diagonal. This relation is then studied in detail and the optimal values of the height-to-width and brace-to-column stiffness ratios, needed to produce the maximum equilibrating lateral force are computed. Further, the single diagonal bracings are applied to typical building frames. Results from elastic analyses are compared with that of the conventional X-braced frame. Pilot analysis shows a reduction of about 2% in the lateral deflection of a typical 24 story braced frame building with rigid connections and five bays using the proposed bracing scheme.     

Design and seismic response of tall chevron panel buckling‐restrained braced steel frames

The numerical analysis of the seismic performance for tall chevron panel buckling‐restrained braced steel frames (PBRBFs) under small and strong earthquake excitations has been carried out to investigate a capacity design procedure for chevron PBRBFs and to examine the effects of axial strength distribution of braces along the height of buildings, vertical supports of braces for the braced beams and the overstrength of braces on the seismic response of PBRBFs. It revealed that the chevron braces that remained elastic can actually provide the vertical supports for the braced beams. Under severe earthquake excitations, the vertical supports deteriorated greatly after braces yielding. The PBRBFs designed by omitting vertical supports of braces for the braced beams and considering the overstrength of braces exhibited superior performance with smaller plastic deformations for braced beams and reduction in ductility demands for panel buckling‐restrained braces (PBRBs) as compared with the others. The distribution of yielding for PBRBs in 10‐story buildings verified that the participation from the higher modes is not very remarkable and that the capacity design based on the first‐mode response can be considered for multistory PBRBFs. Moreover, on the basis of the analysis results of the 30‐story PBRBF, the participation of the higher modes should be taken into account for high‐rise PBRBFs. Copyright © 2011 John Wiley & Sons, Ltd.     

高层建筑结构直接基于位移的抗震设计方法

首先对结构进行自由振动分析,求出各阶振型的弹性自振周期及相应的振型值;然后根据各振型的自振周期,由位移反应谱导出单自由度体系的等效位移,接着由等效原理反推出结构各振型的弹性位移,振型组合后得到结构的位移曲线;再由与性能水平相应的结构层间侧移角限值确定结构各振型目标侧移,对其分别进行分析计算,振型组合求得结构层间剪力,实现了考虑高振型影响的高层建筑结构直接基于位移的抗震设计。通过算例介绍了方法的全过程,并由弹塑性时程分析验证了方法的可行性,为高层建筑结构直接基于位移的抗震设计提供了一个可供参考的思路。     

Calculation model of the lateral stiffness of high‐rise diagrid tube structures based on the modular method

High‐rise diagrid tube structures are widely used in high‐rise buildings because of their strong lateral stiffness and flexible arrangement of plane layout. The lateral stiffness of rectangular diagrid tube structures is studied by many researchers, but it seldom attracts attention for arbitrary polygonal ones. Therefore, it is necessary to propose a calculation model for lateral stiffness of arbitrary polygonal diagrid tube structures. First, the basic concept of modular method is defined. Assuming that diagonals are only subjected to axial force, a calculation model of lateral stiffness of arbitrary polygonal diagrid tube structures is presented. The lateral displacements of structures are calculated by modular method. Then the accuracy of modular method and calculation model of lateral stiffness are verified by finite element method. Intersection law of structural lateral displacement curves is achieved. Taking the top displacement of structures as the reference index and based on the principle of equivalent material, diagonal angle optimization method is proposed, whose rationality is validated by finite element method. Based on the design method of top displacement control, preliminary design method of cross section of diagonals is suggested. Results in this paper are expected to provide a theoretical reference for preliminary engineering design.