bluuebunny/crossref_metadata_2025 huggingface dataset:
Robustly stable active structural control
Authors: Kozodoy D. A. , Spanos P. D.
Published: April 2007

Due to various model uncertainties, most existing control strategies may lead to arbitrarily small stability margins. This paper presents anH2/H2nested control synthesis which combines advantages of the classicalH2andH2‐approaches, and guarantees robust stability. SpecialH2‐maximum andH2‐ultimate system norms are introduced by generalizing the concept of the standardL1,H2andH2norms. These norms reduce the conservatism of the control design specifications while retaining all the benefits of the standardH2‐norm. Both stochastic and deterministic interpretations are addressed. The effectiveness of the new method is illustrated by a numerical example.
Nonlinear response of structures with sliding base isolation
Authors: Bozzo L. , Barbat A. H.
Published: April 2007

It is accepted that sliding or friction base isolation systems effectively protect structures subjected to severe earthquakes. Precise modeling of the sliding connection is, however, still difficult since various parameters influence the friction coefficient. Simplified models, such as those based on a constant friction coefficient, are convenient to understand the behavior of sliding structures and to identify general trends. However, this article shows that for final structural designs (and in particular if the building enters in the nonlinear range) these trends should be used carefully. The purpose of the article is to discuss the general behavior of structures supported on sliding connections and to describe a simple numeric model to take into account variations in the friction coefficient. The numeric model enables to represent complex force‐displacement relationships for the sliding bearings. The model is used to perform a preliminary evaluation of the influence in the response caused by changes in the friction coefficient for elastic and elasto‐plastic structures. The variations in the friction coefficient are obtained from experimental testing for a class of teflon‐based connections.
Chaotic behaviour of hysteretic oscillators
Authors: Battaini M. , Casciati F.
Published: April 2007

Attention is focused on low‐damping‐rubber base‐isolators. Instead of thinking in terms of intelligent materials, this paper pursues the definition of conditions of behaviour which result intelligent in view of a coupling with an active control device (hybrid control). In particular, situations which show a chaotic behaviour of the dynamic response to external excitations are promising in terms of control efficiency. The regions of chaotic behaviour are identified by evaluation of the corresponding Lyapunov exponents.
The main sources of helicopter vibration and noise emissions and adaptive concepts to reduce them
Authors: Breitbach E. , Büter A.
Published: April 2007

This paper deals with the sources of helicopter vibration and noise emissions. It shows and evaluates adaptive concepts to reduce them. The main reasons for these emissions are aerodynamic effects such as blade‐vortex‐inter action (BVI), aerodynamic hysteresis, and local transonic effects at the forward moving blade.

After a review of conventional control concepts to reduce the vibrations and/or sound emissions, the possibilities to realise an adaptive rotorblade are explained.

The understanding of the interaction between the aerodynamic sources and the resulting vibrations and noise is the basis of the design of optimal control concepts.
Hybrid feedback‐feedforward control for vibration suppression
Authors: de Man Pierre , Preumont André
Published: April 2007

This paper evaluates a hybrid feedback‐feedforward controller for vibration suppression. The synergy between the two types of controllers is pointed out. The feedforward control extends the bandwidth of the controller for steady state disturbances with a correlated reference, while the feedback control reduces drastically the impulse response of lightly damped structures, avoiding the problems associated with truncation. The hybrid controller does not require additional actuator and sensor. Two applications are presented in the area of vibration attenuation and precision pointing. In each case the theoretical advantage of the hybrid controller is confirmed by experiments.
On the complex zeros of non‐colocated systems
Authors: Loix Nicolas , Kozanek Jan , Foltete Emmanuel
Published: April 2007

This paper shows that, in some circomstances, conservative systems may possess complex zeros. The presence of these complex zeros seems to reduce the robustness of the control system with respect to parameter variations.
On krylov matrices and controllability of n‐dimensional linear time‐invariant state equations
Authors: Maćkiewicz Andrzej , Almansa Francisco López , Inaudi José A.
Published: April 2007

The classical Rosenbrock's algorithm (based on the Gauss elimination method) for n‐dimensional linear time invariant state equation matrices is analysed and modernized. The method of orthogonal similarity reduction to block Hessenberg form is used to assure numerical stability. The updated version of the Rosenbrock's algorithm is then justified in a very easy way using properties of Krylov matrices. Additionally, this algorithm can be used to determine an equivalence transformation which converts an n‐dimensional linear state equation into a controllable form (or a time invariant one into an equivalent observable form). It is advantageous for big and medium size problems and can be easily parallelized. Numerical examples are presented.
Feedback controllers for active vibration suppression
Authors: Petitjean B. , Legrain I.
Published: April 2007

The aim of the present paper is to investigate two strategies for the active control of plate vibrations, using distributed sensors and actuators (PVDF patches) working on a wide frequency band. The two strategies correspond to the two ends of a spectrum ranging from very robust/less efficient schemes (analog static output feedback) to less robust/very efficient schemes (here ‘frequency shaped LQG’).

Both have been experimentally tested and have given successful attenuations; the efficiency of both approaches is demonstrated on sensor signals involved in the control loop as well as on radiated pressure measurements, which constitute an independent index of performance.

It is shown that ‘frequency shaped LQG’ is a viable approach to feedback control of lightly damped structures, and that its robustness can be enhanced through a careful design.

LQG is a model‐based method, and hence requires the modeling of the active structure. Two approaches are investigated in this paper: a finite element model and a identified model built from the experimentally measured transfer functions.
Response of base isolated systems equipped with tuned mass dampers to random excitations
Authors: Palazzo B. , Petti L. , de Ligio M.
Published: April 2007

A new structural system conceived to control Base Isolated System vibrations under random excitations is analyzed. The new system combines the Tuned Mass Damping strategy with the Isolation concept in order to obtain a new system which principally attenuates the effects of the seismic excitation components with frequencies close to the fundamental natural vibration one. The Random response of equivalent linear Base Isolated Systems controlled by Tuned Mass Dampers subject to horizontal random excitations is analyzed. Considering the superstructure motion described by its first modal contribution, a three‐degree‐of‐freedom linear model subject to stationary Gaussian excitations, modelled by the modified Kanai‐Tajimi power density spectrum, was used in this analysis. The standard deviation response ratio of the new system respect to the one of the base isolated system was evaluated based on a wide range of parameters. Optimal parameters which minimize structural response were also obtained.
Active control of drillstring vibrations by mode localization
Authors: Yigit A. S. , Al‐Ansary M. D. , Khalid M.
Published: April 2007

A method of controlling vibrations in a drillstring is proposed. The method is based on altering the system eigenstructure by feedback such that the closed loop system mode shapes are spatially confined to small geometric regions. Both active and passive means can be used to realize the resulting designs. Simulations are used to show the effect of limited actuator placement and robustness to parameter uncertainties.
Effects of structural uncertainties on TMD design: A reliability‐based approach
Authors: Papadimitriou C. , Katafygiotis L. S. , Au Siu‐Kui
Published: April 2007

This study investigates the effects of structural uncertainties on the design and performance evaluation of passive tuned mass dampers (TMD) used for vibration control. A probabilistic optimal design methodology is presented in which time‐invariant uncertain structural parameters are modelled by random variables with prescribed probability distribution. Unlike conventional TMD designs based on minimizing the mean‐square response, a reliability‐based performance index is considered in the proposed design which properly accounts for uncertainties in load and structural models. An approximate asymptotic expansion is used to compute the multidimensional reliability integrals arising in the proposed optimal design methodology. Accuracy and effectiveness issues are addressed by comparing results obtained using this approximation with corresponding results obtained by numerical integration. The importance of structural uncertainties is demonstrated by applying the methodology to a single degree of freedom structure subjected to broadband excitations that are modelled by stationary white noise. It is found that the consideration of structural uncertainties improves substantially the robustness of the TMD design. Also, the reliability‐based TMD‐design methodology results into significantly larger structural reliability compared to that obtained by the conventional design approach based on minimizing the mean‐square response.
Concept of super‐high‐rise building (DIB‐200)
Authors: Kobori Takuji , Ban Shigeru , Kubota Toshihiko , Yamada Kazuhiko
Published: April 2007

This report presents an overall study on how the concept of a 200‐story super‐high‐rise building can be realized. In the beginning, various planning requirements appertaining to the architecture, appurtenant utilities, disaster prevention, and construction are briefly discussed. Next, structural studies, i.e. design criteria, external loads requiring study, and the results of response analyses, are described in more detail. Examination of these items confirms that it is possible to construct a 200‐story super‐high‐rise building by applying the currently available technology. However, it is found that a seismic response control system is essential for improving the living comfort of such a building.
Free spanning ductile vierendeel frame: A system for high‐rise buildings in seismic areas
Authors: Banavalkar P. V.
Published: April 2007

The paper has described the composition and structural behavior of a free spanning ductile frame system to be used in seismic areas. The inelastic performance, ductility, and redundancy of the system is compared with a conventional ductile moment resisting frame. It is shown that the structural performance of the system is equal or better than the conventional system. The paper also describes successful application of the system to commercial high‐rise buildings.
Tuned‐pendulum mass damper installed in crystal tower
Authors: Nagase Tadashi , Hisatoku Toshiharu
Published: April 2007

A new damper to reduce the lateral vibration of buildings has been developed and installed in a 37‐story office building: Crystal Tower, Osaka. The tower has a slender proportion of height—width ratio 6. The damper can decrease wind‐induced motion by 50%. Crystal Tower is the first high‐rise building with this damper in Japan, and the damper weight, 540 tons (1190 kips), is large compared with others in use elsewhere in the world. The damper is a pendulum‐type tuned‐mass damper and the ice thermal storage tanks for air conditioning are used as the moving mass of the damper. The TMD of Crystal Tower, therefore, needs no additional mass weight nor space for installing. This paper presents some intrinsic features of the damper and demonstrates how simple and practical the damper is. Special considerations are given both to the connecting joints between the tank and the building and also to the sloshing behavior of the liquid contents. Typhoon and earthquake records observed in Crystal Tower have proved that the damper works as well as expected.
Experimental testing of ductile cladding connections for building facades
Authors: Pinelli Jean‐Paul , Moor Christian , Craig James I. , Goodno Barry J.
Published: April 2007

A ductile cladding connection is a special connecting device between a facade cladding panel and a building structure that is designed to dissipate energy when subjected to an earthquake. The effect of such a device is to reduce the overall seismic response of the structure. A special testing machine was designed to test the behavior of these advanced cladding connections. The machine, which is specially suited for the recording and evaluation of ductility and damping properties, is described. Its main characteristics are both the ability to load a specimen in shear simultaneously in two orthogonal directions without inducing any axial stress, and the flexibility to test a wide variety of different damping mechanisms with different geometric configurations. The machine was used to test a family of advanced cladding connections that employs ductile flexural action to achieve high and stable levels of ductility for repeated cyclic load applications. A lumped‐parameter mechanical model for these connections was identified from selected test data, and the predicted cyclic behavior was shown to agree well with test data. The model is simple and suitable for incorporation into nonlinear structural analysis programs.
Masonry wall frame design and performance
Authors: Hart Gary C. , Priestley M. J. Nigel , Seible Frieder
Published: April 2007

Tall masonry building in active seismic or severe wind regions have typically been designed as shear wall buildings. This paper presents an alternative lateral force resisting system cailed a wall frame. This new masonry system is particularly advantageous for seismic and windy regions because it utilizes the nonlinear inelastic load deformation characteristics of the masonry beams and is thus a ductile system. Basic design assumptions and experimental test data are presented.
Dynamic characteristics of five tall buildings during strong and low‐amplitude motions
Authors: Çlelebi M. , Phan L. T. , Marshall R. D.
Published: April 2007

The objectives of this paper are to present (1) a comparison of dynamic characteristics of five buildings determined from recorded strong‐motion response data and from low‐amplitude (ambient vibration) tests, and (2) a description of the low‐amplitude ambient testing and PC‐based data‐acquisition approach that is integrated with the permanent strong‐motion instrumentation in the five buildings. All five buildings are within the San Francisco Bay area and the strong‐motion dynamic characteristics are extracted from the October 17, 1989 Loma Prieta earthquake response records. Ambient vibration tests on the same five buildings were conducted in September 1990. Analyses of strong‐motion response and low‐amplitude test data have been performed by many investigators. The present study differs from numerous previous investigations because (1) in this study, accelerometers in the five permanently‐instrumented buildings were used during the low‐amplitude testing, and (2) rapid screening of the strong‐motion response data was achieved with a concerted use of system identification software. The results show for all cases that the fundamental periods and corresponding percentages of critical damping determined from low‐amplitude tests are appreciably lower than those determined from strong‐motion response records. The data set collected during this study is a useful contribution to the data base of dynamic characteristics of engineered structures and reconfirms the differences between the dynamic characteristics identified from strong‐motion records and from low‐amplitude tests.
An efficient resizing technique for the design of tall steel buildings subject to multiple drift constraints
Authors: Chan Chun‐Man , Grierson Donald E.
Published: April 2007

This paper presents an efficient resizing technique for the optimum design of tall steel building frameworks. Specifically, an ‘optimality criteria’ method is applied to minimize the weight of a lateral load‐resisting structural system of fixed topology subject to constraints on interstorey drift. By exploiting the fact for building frameworks that member forces are relatively insensitive to changes in member sizes, rigorously‐derived optimality criteria are shown to be readily satisfied through an iterative pseudo‐discrete optimization procedure that converges in but a few cycles to a least‐weight design using commercial‐standard steel sections. While not considered herein, it is a simple matter to extend the stiffness‐based design procedure to account also for strength requirements. Two building framework examples are presented to illustrate the features of the design optimization method.
Seismic response of structures with supplemental damping
Authors: Constantinou M. C. , Symans M. D.
Published: April 2007

This paper presents a review of supplemental damping devices used for the control of the seismic response of structures. The mechanical properties of these devices are discussed and considerations in the design of energy absorbing systems are presented.
Experimental study of seismic response of buildings with supplemental fluid dampers
Authors: Constantinou M. C. , Symans M. D.
Published: April 2007

This paper presents the results of an experimental study of the seismic response of buildings with supplemental fluid damping devices. These devices operate on the principle of fluid flow through orifices specially shaped so as to produce damping forces proportional to the velocity, i.e. the devices operate as linear viscous dampers. The experimental results demonstrate that the addition of fluid dampers to the tested steel model structure resulted in reductions of interstory drifts, floor accelerations and story shear forces by factors of two to three in comparison with the response of the same structure without the dampers.
Nonlinear static finite element analysis of reinforced masonry walls in tall buildings
Authors: Ewing Robert D.
Published: April 2007

A finite element computer program or code, FEM/I, has been developed for the nonlinear, static analysis of reinforced masonry building components subjected to in‐plane loading. The masonry is represented by a material with bimodular orthotropy, and includes tension stiffening, compression softening, and strain softening, as well as a degrading unloading rule. The masonry model incorporates a tension crack orientation adjustment approach, where the orientation of the final cracks can be different from the initial cracks. The model also includes a compressive strength reduction after tensile cracking normal to the principal compressive strains. Additionally, the model includes a compressive strength increase due to lateral compressive confinement. The reinforcement is represented by an orthotropic material with a bilinear stress‐strain relationship and includes unloading. The FEM/I code is operational on IBM compatible personal computers, such as the 286/386/486 systems. This capability makes the developed technology available to a large group of engineers and researchers, since a large main frame computer is not required to operate the program. The computer program is expected to be particularly useful to designers of tall reinforced masonry buildings that contain components with unusual configurations. These components can be analyzed to properly assess their structural performance.
Conditions that give rise to unusually large long period ground motions
Authors: Somerville Paul , Graves Robert
Published: April 2007

Several ground motion conditions that are of little concern for conventional structures can be quite important for structures having natural periods longer than 1 s. Firstly, a large long‐period pulse of motion, due to the effect of rupture propagation (directivity), is observed in the direction normal to the fault at strong motion stations located close to the fault. The fault‐normal motions are about twice as large as the fault‐parallel motions for periods longer than about 1 s. The importance of this effect, especially in strike‐slip earthquakes, has probably been underestimated in existing ground motion attenuation relations because until very recently most of the near‐fault strong motion data from large earthquakes have come from thrust earthquakes, for which directivity effects are usually less pronounced. Near‐fault recordings of the 1971 San Fernando, 1979 Imperial Valley, 1989 Loma Prieta, and 1992 Landers, California, earthquakes show large directivity effects. We describe the systematic characteristics of the directivity effect derived from empirical analysis of recorded data and from synthetic seismogram modeling of these data. Secondly, the trapping and amplification of long period waves by sedimentary basins can generate amplitudes that are significantly larger than those calculated from simple ID models of site resonance. Using a ID model with a plane wave incident from below, it is not possible to trap energy in the near‐surface sediment layers. However, for 2D and 3D basin models, waves become trapped as they enter the thickening edge of a basin, and partially escape as they reach the thinning edge of the basin. We show evidence from both recorded data and synthetic seismogram modeling of the San Fernando and Loma Prieta earthquakes that the surface waves are confined to the basin and are not recorded at rock sites adjacent to the basin. This implies that the long period ground motion response at sites within these basins is not adequately represented by the conventional approach of vertically propagating an adjacent rock recording through a ID soil column.
On the lateral response of regular highrise frames
Authors: Grigorian Mark
Published: April 2007

This paper introduces a simple approach for the study of the structural phenomena associated with the lateral response of regular highrise frames. The concept is based upon the assumption that the structure is composed of imaginary modules that fit within the actual bays of the framework, and that all imaginary modules deform through similar shapes by formation of points of inflexion at similar locations. The imaginary modules of a story are combined to form an equivalent ‘basic module’ that possesses the same structural characteristics as the corresponding story level subframe. The concept is used to establish an analogy between the lateral response of highrise structures and discretized Timoshenko beam‐columns with similar boundary conditions. The properties of the basic module have been employed in conjunction with the techniques of finite difference calculus to derive the governing equation of motion of a regular discretized Timoshenko beam under uniform compression. The use of the concept is further utilized to obtain a number of closed form formulae for the initial design of multistory structures. These include expressions for the determination of the natural frequencies, theP‐delta effects, as well as the critical buckling loads of regular multistory frames. Numerical examples have been provided to demonstrate the applications and the simplicity of the proposed solutions.
System of programs for analysis of three‐dimensional shear wall structures
Authors: Wdowicki Jacek , Wdowicka Elżbieta
Published: April 2007

The paper presents a system of programs for calculating stresses and displacements in three‐dimensional shear wall structures with uniform properties throughout the height. The analysis is carried out on the basis of the continuous connection method. The system allows for considering lateral and vertical loads, arbitrarily located in the plan and arbitrarily distributed along the height. The system is user‐oriented and inexpensive in operation. Two numerical examples are given in the paper.
Secondary web‐flange interaction in framed‐tube buildings
Authors: Singh Y. , Nagpal A. K.
Published: April 2007

In the conventional plane‐frame model of framed‐tube buildings, only the primary interaction between the web frame and the flange frame is considered, through vertical shear transfer at corner columns. In addition to this, a secondary interaction takes place due to horizontal shear transfer at each floor level, through the floor slab having high in‐plane rigidity. This interaction causes a discrepancy in member forces of a few bottom and top storeys. A simple modification is suggested in the form of an additional cantilever column connected to the conventional plane‐frame model by axial force transfer members at every floor level. The improved model yields member forces in all the storeys that are very close to those obtained using 3D analysis.
Supertall buildings with tuned mass damper
Authors: Youssef Nabih
Published: April 2007

This paper introduces the ‘mega structure’ concept for supertall buildings. This concept incorporates the latest technology for structural energy dissipation and control systems, which are capable of predicting, controlling and modifying building motion/response. The implementation of tuned mass dampers (TMD) on a 150‐story building in Los Angeles is presented. Following a brief introduction to the underlying mathematical theory of TMD, the dynamic response of the building structure is presented demonstrating the effectiveness of TMD in suppressing undesirable building motions. The influence of the TMD configuration on global system efficiency is also investigated via parametric studies.
Structural reliability characterization of precast concrete
Authors: Ekwueme Chukwuma G. , Hart Gary C.
Published: April 2007

The development of structural reliability‐based design criteria requires an uncertainty characterization of structures. This paper proposes a new method of structural reliability characterization for precast concrete frames. Beam—column‐joint subassemblies are designated as the substructures that form the basis of structural reliability characterization as opposed to the use of individual beams and columns.
Optimum structural design based on seismic reliability and response distribution
Authors: Asano Koichiro , Harada Hiroyuki
Published: April 2007

An analytical approach to the optimum structural design parameters is developed on the basis of seismic reliability and inter‐story response distribution. An earthquake‐like stationary random excitation being assumed, probabilistic earthquake response is estimated as the solution of a simple simultaneous algebraic equation. Based on this probabilistic earthquake response, the optimum parameters are determined by selecting seismic structural reliability and an inter‐story response distribution index as objective functions. The validity of this approach is demonstrated by examining the perspective and contour lines of the objective functions regarded as a function of design parameters for elastic structural systems with six degrees of freedom. The possible application of this approach is also presented to the determination of elasto‐plastic structural parameters with bi‐linear hysteretic characteristics. Other aspects of the approach's validity are also examined from the response distribution viewpoint for the elastic structural system with recorded strong earthquake motions. The influence of the higher modal response and the earthquake's predominant angular frequency on the optimum parameters are also discussed.
Two‐stage gravity load analysis of framed‐tube buildings
Authors: Singh Y. , Nagpal A. K.
Published: April 2007

A two‐stage solution procedure has been presented for the gravity loading (live load) analysis of framed‐tube buildings. In the first stage, the solution is estimated by solving a simplified model and a number of substructures with much reduced numbers of degrees of freedom. In the second stage, the Gauss‐Seidel iterative procedure is used to obtain the accurate solution. The proposed two‐stage solution procedure requires a CPU time that is only a fraction of that needed in the standard solution procedure. The number of computer storage locations required is also small. Additionally, by using the proposed procedure, framed‐tubed buildings of practically any size can be analysed on microcomputers.
Seismic response of building structures with flexible inelastic diaphragm
Authors: Dolce M. , Lorusso V. D. , Masi A.
Published: April 2007

The inelastic response of one‐storey buildings subjected to lateral loads is analysed, making allowance for the real in‐plane rigidity and strength of the floors. The structural model consists of a floor diaphragm supported by seven vertical resisting elements with degrading stiffness properties. The elastic design analysis is carried out by modelling the floor diaphragm as a rigid or, alternatively, as a flexible beam. The actual nonlinear response of 240 structures is studied via numerical simulations. Different stiffness and strength distributions in the lateral resisting systems and in the diaphragm are considered. The results of the investigation emphasize the need for an adequate design of the floor diaphragm as a structural element. Also, the results show that the deformability of the diaphragms plays an important role only if the lateral‐force resisting system has a markedly non‐uniform stiffness distribution; even in such cases, however, adopting the rigid diaphragm hypothesis leads to a more conservative design.
Symmetry breaking: The effect of randomizing mass and stiffness on building response to winds and earthquakes
Authors: Meecham William C. , Mal Ajit K.
Published: April 2007

Symmetry‐breaking can have profound consequences for the response of periodic structures. Examples of such structures include tall buildings and their response to winds and earthquakes; repeated trusses in bridge structures and, similarly, repeated trusses for space vehicles; there are many others. These results are discussed for various dampings, various building heights and various excitations with a view to finding building response. Variation of up to ± 20% in the parameters shows displacements (RMS or maximum) of up to two to three times those for the deterministic structure (no variation in parameters). Buildings of 3 to 50 floors are considered. The greatest effects are seen near lower frequency resonances for all structures. The biggest effects are seen for the tallest structures: in such cases amplification of up to a factor of four occur.
A survey of glazing system behavior in multi‐story buildings during hurricane andrew
Authors: Behr Richard A. , Minor Joseph E.
Published: April 2007

A focused survey of glazing system behavior in multi‐story buildings in the direct aftermath of Hurricane Andrew was conducted. Seventeen buildings and four building complexes were examined between 26 August and 30 August, 1992. The buildings surveyed spanned a 32 km (19 mile) distance from Miami on the north to Cutler Ridge on the south. With few exceptions, glazing systems performed poorly and damage to building contents was extensive. The following specific observations were made: (1) impacts from windborne debris were a dominant cause of glass failure; (2) wall system anchorages sometimes failed; (3) prevention of ‘blow‐through’ after internal pressurization significantly mitigated storm damage to building interiors; and (4) outer‐lite‐only failures occurred on some insulating glass units. Results of the survey underscore the vital importance of maintaining the integrity of a building envelope during a severe windstorm. Windborne debris must be considered in the design of architectural glazing systems, as must proper anchorages of glazing systems to building framing members.
A computer‐based design support system for steel frame structures
Authors: Fuyama Hiroyuki , Krawinkler Helmut , Law Kincho H.
Published: April 2007

This paper describes the development and utilization of a computer‐based support system for the conceptual design of moment resisting steel frame structures. This design support system, ‘Building Engineering and Reasoning Tool’ (BERT), incorporates a behavior‐based methodology for designing structural members that satisfy strength and interstory drift requirements due to gravity and lateral (earthquake) loads. Given the loading conditions and building configuration, BERT has the capability of selecting efficient member sizes through reasoning about the behavior of the structure. Different configurations can be evaluated by means of a cost estimating scheme that incorporates steel material, fabrication, and erection costs. This paper focuses on a discussion of the design methodology implemented in BERT. Illustrative examples are presented to demonstrate the range of applications of this design support system.
Rescue mission of Ryounkaku Tower in Great Kanto Earthquake; travelling back in time to 1923 to apply the latest aseismic technologies
Authors: Kobori Takuji , Nakahara Mitsuharu
Published: April 2007

In 1890, a twelve‐story octagonal sight‐seeing tower was constructed as a high rise building in Tokyo Asakusa Park. In 1923, however, the top of the tower from the eighth floor up collapsed due to the Great Kanto Earthquake. In order to raise public interest in disaster prevention, we performed as a virtual experiment a conceptual attempt to save the tower without fundamentally changing its architectural characteristics by applying the most advanced structural control techniques. In the simulation, the top of the tower from the eighth floor experienced, almost exactly as described in historical record, a shear fracture during the initial period of principal shock. The modified Ryounkaku Tower would have ensured a comfortable margin of safety even against earthquakes more severe than the Great Kanto Earthquake in 1923.
Mode coupling in the torsional—flexural buckling of regular multistorey buildings
Authors: Zalka K. A.
Published: April 2007

An analogy is established between the mode coupling of columns under concentrated end forces and those subjected to uniformly distributed axial forces. It is demonstrated that the cubic equation derived for the mode coupling of columns under end forces can be used directly for the more practical case of cantilevers under uniformly distributed axial load. Simple closed‐form formulae and design tables are given for the torsional—flexural buckling of cantilevers. These formulae can be used directly for the spatial stability analysis of core supported regular multistorey buildings. A numerical example is provided to show the step‐by‐step procedure to be followed in practical structural design for stability. The results of a series of tests on small‐scale multistorey building models are presented. The loadbearing system of the models consists of columns, shear walls and support cores. The results indicate that the contribution of the columns to the lateral and warping stiffness of the support system may be of considerable magnitude. The more sensitive the structure is to torsion, the greater the effect of the columns.
Utilization of high‐strength concrete in tall buildings
Authors: Hu Qingchang , Zhu Zingquan
Published: April 2007

Since 1988, the utilization of high strength concrete has increased owing to the development of tall buildings in many cities of China. High strength concrete is usually used for columns; the advantages are saving floor area and providing better seismic behavior. Composite columns are also adopted under heavily loaded conditions. In this paper, the design of two representative tall buildings in Beijing are briefly introduced.
Deficiencies of design‐spectrum compatible accelerograms
Authors: Naeim Farzad , Lew Marshall
Published: April 2007

Frequency‐domain scaled, design spectrum compatible acceleration time histories (DSCTH) are widely used in the analysis and design of special structures, particularly seismic‐isolated buildings. At the first glance, it seems that DSCTH records furnish earthquake resistant designers with a consistency and compatibility bridge between the two very different worlds of elastic and inelastic response. Closer examination reveals, however, that there are significant potential problems associated with indiscriminate use of DSCTH records in seismic design.
Estimation of wind loads for a super‐tall building (SSH)
Authors: Shimada Kenji , Hibi Kazuki
Published: April 2007

A procedure is presented for estimating the wind load acting on the Shimizu Super Highrise, which is based on results obtained from wind tunnel experiments. The force balance test and the two‐degree‐of‐freedom aeroelastic model test were performed. A considerable reduction in the dynamic wind force and moderate variations in the response for various wind directions could be obtained as a result of suppression of vortex shedding attributed to the effect produced by the alternate arrangement of different cross sections along the height of the building.
Estimating seismic drifts of multistory reinforced concrete frames
Authors: Uang Chia‐Ming , Maarouf Ahmed
Published: April 2007

In order to estimate maximum roof and story drifts occurring in major earthquakes, seismic design provisions usually specify a deflection amplification factor (DAF) to amplify elastic design drifts. A comparison of several seismic design provisions indicated that the deflection amplification factor in both the UBC and NEHRP Recommended Provisions, being equal to 3Rw/8 and Cd, respectively, is very low and could lead to unconservative drift estimations. Since a reliable estimate of actual seismic drifts is essential for developing a performance‐based seismic design provision to control both structural and non‐structural damage, an analytical study of the seismic response of three instrumented reinforced concrete building frames located in California was first conducted. In addition to analytical studies, reported test results from shaking table testing of reduced‐scale multistory reinforced concrete frames were used to evaluate the deflection amplification factor. It is confirmed from both the analytical and experimental evidence that drifts developed in major earthquakes are much higher than those predicted by the UBC or NEHRP approach. It is recommended that the deflection amplification factor be increased to at least the seismic force reduction factor (Rw in UBC and R in NEHRP) for estimating maximum drifts.
The use of single diagonal bracing in improvement of the lateral response of tall buildings
Authors: Vafai A. , Estekanchi H. , Mofid M.
Published: April 2007

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.
A simplified analysis of doubly symmetric tube structures
Authors: Takabatake Hideo , Takesako Ryoichi , Kobayashi Masaki
Published: April 2007

This paper discusses the exactness of a simplified analytical method proposed by Takabatake et al. (1993) to use in preliminary stages of the design to doubly symmetric single and double frame‐tubes in high‐rise structures. The simplified method is formulated by replacing the tube with an equivalent rod, including the effect of the bending, transverse shear deformation, shear‐lag and torsion. The discontinuous variation of sectional stiffness of tube structures, due to the variation of frame members and attached braces, is expressed as a continuous function by means of the extended Dirac function. The exactness of the closed‐form solutions proposed here for the deflection, shear‐lag, and torsional angle of variable tube structures with braces is established from static and dynamic numerical results for doubly symmetric single and double frame‐tubes with braces, in which the results obtained from the proposed solutions are compared with results obtained from three‐dimensional frame analysis using the FEM codes NASTRAN and DEMOS.
A new method for the design of tall buildings: The mit design method
Authors: Pouangare C. C. , Connor J. J.
Published: April 2007

A new method for the design of tall and super‐tall buildings is presented in this paper. The method is based on transforming the stiffness properties of the building to equivalent beam properties. The equivalent beam is allowed to deform both in bending and shear to capture the true behavior of the building. The method is a stiffness based approach that later requires checks for strength. This is quite appropriate since the design of tall and super‐tall buildings is governed by stiffness and not by strength. Knowing the load and assuming a desired shape of the beam, the required shear and bending rigidities of the beam can be calculated. The method is robust and easy to apply, and is particularly suited for space truss systems. The simplicity and efficiency of the method are illustrated with an example.
Framing sliver buildings
Authors: Cruvellier Mark R. , Smith Bryan Stafford
Published: April 2007

Over the past decade, one of the most remarkable advances in tall building design has been their construction to unprecedented slenderness ratios. In this paper, the authors review some of the basic and innovative structural framing arrangements that have been found from first‐hand experience to be particularly appropriate to so‐called ‘sliver’ buildings. Also, case studies of four landmark New York City buildings are presented in which some of these framing concepts have been applied.
Assessing the damping properties of coupled wall structural systems
Authors: Moazzami Sara
Published: April 2007

In this paper, the global response of the coupled shear wall assemblies will be studied at two different limit states. The primary objective of this investigation is to establish upper and lower bounds on the level of the damping that will be induced in the system due to yield excursions and energy dissipation of the structural members.
Design of coupled wall structural systems
Authors: Moazzami Sara
Published: April 2007

In most building codes, there are very limited guidelines regarding the proportioning of the walls and coupling beams. Consequently, the response of the coupled wall assemblies during a moderate to major earthquake has been noted to fall short of acceptable ductile behavior (see J. Moehle (Ed.), ‘Preliminary report on the seismological and engineering aspects of the January 17, 1994 Northridge earthquake’, Report No. UCB/EERC‐94/01, Earthquake Engineering Research Centre, University of California at Berkeley, January 1994). The objective of this paper is to discuss some of the current practices in the proportioning and design of coupled wall assemblies, highlight some of the shortcomings of these methods, and provide a new design guideline aimed at a more comprehensive design of structures.
Dynamic study of ductile framed shearwalls
Authors: Dai Hang , Ding Dajun
Published: April 2007

Based on FEM analysis and low frequency cyclic loading testing, this paper successfully proposes a new breed of ductile framed shearwall with numerous short horizontal keyways to constitute a X‐shaped weakening for improving its earthquake resistance. By adopting the above design innovation, two 4‐story R.C. shearwall models of 1:16 scale (with one ordinarily designed wall tested on the same base beam as the comparison) were constructed and a shaking table test was conducted by direct earthquake inputs, the test went through the whole process of elastic, cracking and failing stages of the models; a comparison of the dynamic response and behavior between these two models was also made. The results demonstrate that the suggested shearwall has a much better capacity for earthquake resistance.
State of the art of the construction and design of and research on tall buildings in the people's Republic of China
Authors: Ding Dajun
Published: April 2007

This paper presents the general situation and developing characteristics of tall buildings in the People's Republic of China and gives typical examples of structural systems consisting of frames, frame‐shearwalls, shearwalls, frames supporting shearwalls and tubes. It also provides a basic survey of the foundations used in tall buildings. Finally, structural design and relevant experimental research are introduced briefly.
Seismic performance analysis of a multistory steel moment frame building damaged during the 1994 Northridge earthquake
Authors: Naeim Frazad , Dijulio Roger M. , Benuska Kalman V. , Reinhorn Andrei M. , Li Chen
Published: April 2007

This paper presents results of performance analysis studies on an eleven story steel moment frame building located in west Los Angeles which was damaged during the 17 January 1994 Northridge earthquake. Extensive field inspections of damage were performed prior to the start of this investigation. These inspections/tests revealed some degree of damage in more than 28% of the moment frame joints of the building. Extensive two‐ and three‐dimensional, linear and nonlinear, static and dynamic analyses of the building are conducted as a part of this study to investigate and correlate observed damage with various elastic and inelastic analytical damage predictors. Statistical correlations of observed damage patterns with various analytical damage indicators are presented.