bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control strategies for a slender structure
Authors: Roberti Vincent , Lamarque Claude Henri , Jezequel Louis 
Published: April 2007

AbstractIn this study we start from a modelization by finite elements of a 150 m high tower and try to introduce various control scenarii into the model. The model is realistic in terms of orders of physical size for masses, stiffnesses and other geometrical and mechanical data. We hope to compare control strategies on this model. Each of the control process is compatible with a technological achievement (e.g dampers). The control is provided by actuators that must be located in the building. We compare the energies to get in each control type and the reached efficiency. The global target is to find out a control law model technologically transposable to an actual structure and to define the best control strategy, i.e. to find out the best compromise between the energy to be provided, the reducing in vibratory levels, the actuator location and the actuator operating safety. These elements could be defined as “control criteria”. Among the several possible sollicitations, we will focus on seism‐type sollicitations and will define the actuators location in relation to the building architecture. We will simulate the building behaviours with and without control and will compare the results in terms of vibratory level reductions and energies at work.
Active structures for vibration suppression and precision pointing
Authors: Preumont André 
Published: April 2007

AbstractThis paper describes the work performed at ULB for the development of active structures for space applications, using the piezoelectric technology. The control strategy involves two embedded control loops. The inner loop consists of a decentralized active damping using colocated actuator‐sensor pairs and control schemes with guaranteed stability properties. The outer loop consists of a pointing or position control using non‐colocated actuators and sensors. Two examples of active damping are presented: a truss with linear actuators and a plate with piezo strips. Next, a position control is developed for the truss. The control law is derived from the frequency‐shaped LQG methodology, using a simplified model of the actively damped structure; the band‐width of the control system includes the first two flexible modes of the structure. It is demonstrated that the active damping improves substantially the performance and the robustness of the position control loop, inside and outside its bandwidth.
Displacement feedback control of structures
Authors: Chung L. L. , Wu L. Y. , Jin T. G. 
Published: April 2007

AbstractEven though displacement signal is superior to velocity and acceleration signals from the viewpoint of measurement noise, direct displacement feedback is considered to be unfeasible. In this paper, displacements of the previous time steps are also introduced into the on‐line calculation of the control forces so that displacement feedback control becomes feasible. A multi‐step displacement feedback control algorithm is derived through optimization process such that certain prescribed quadratic performance index is minimized. Control forces are simply generated from displacement information of the current and previous time steps. The feasibility of the proposed control algorithm is verified numerically by the tendon control of structures subjected to real earthquake excitation. The control effectiveness of the proposed control algorithm is close to that of state feedback control algorithm. A small number of sensors and controllers, and simple on‐line calculation of control forces, make the proposed control algorithm favorable to real‐time control implementation.
Combined fuzzy‐deterministic semi‐active control of a landing gear
Authors: Fiume I. , Ghiringhelli G. L. 
Published: April 2007

AbstractA fuzzy correction of a deterministic semi‐active control applied to an aircraft landing gear is presented. An existing computer code has been modified to allow its numerical verification during simulated drop tests and landings. The correction of the control action applied by the fuzzy controller seems to improve the dynamic response by reducing the amplitude of vertical ground load fluctuations.
Effect of time lag and use of compensators in the active control of buildings subjected to earthquake excitations
Authors: Suner Ahmet , Nagchaudhuri Abhijit , Utku Senol 
Published: April 2007

AbstractThis work studies the determination of controls to suppress the vibration of a building structure subjected to earthquake excitation. Also studied are the effect of time delay in controls on the response of the structure, determination of time delay limits, and time delay compensation. The control problem is nonautonomous due to the existence of external excitation during the application of controls. The control methods that are used in the autonomous system cannot be applied directly to the nonautonomous problem. Therefore the methods that may be applicable to the nonautonomous problem need to be investigated. In this study, the problem is formulated as a disturbance rejection problem. Determination of controls is discussed with the help of insight provided by classical control methods. A simple control method which is based on large feedback gains is implemented. Time delay effect and compensation are studied through the use of classical control methods.
Analogue vibration cancellation by means of piezoelectric elements
Authors: Jenkins D. F. L. , Cunningham M. J. , Clegg W. W. 
Published: April 2007

AbstractAn active vibration control system has been developed based upon analogue feedback and optical vibration sensing. Composite piezoelectric films have been deposited directly onto the cantilever to provide a means of actuation and micro‐positioning. The system operates such that unwanted vibrations in the cantilever are removed and yet it remains possible to deflect the cantilever statically or dynamically as required. Results are presented for such a system.
Modelling of a plate including a distribution of piezoelectric transducers and an electronic network ‐ optimization of circuit parameters
Authors: Lenczner Michel 
Published: April 2007

AbstractThe Besançon “Matériaux Intelligents” group is working on theoretical and practical aspects of design of dynamical stabilizers for realistic distributed systems. This paper is related to the modelling of an elastic multilayered plate including distributed piezoelectric actuators and a distributed electrical circuit. The derivation of the model is based on asymptotic methods. It is shown that the electrical circuit is a dynamical stabilizer for plate vibrations. An optimization procedure of circuit parameters is formulated and numerical results are discussed.
Feedback control of flexural waves in beams
Authors: Mace B. R. , Jones R. W. 
Published: April 2007

AbstractThe control of bending waves in a thin beam using a collocated feedback method is discussed with special reference to the case of a system comprising a displacement sensor and a force actuator. Control strategies involving vibration isolation (i.e. reducing wave transmission) and energy absorption (i.e. reducing scattered energy) are considered. Digital implementation is discussed and some results presented.
Non Gaussian closure techniques for the analysis of R‐FBI isolation system
Authors: Muscolino G. , Pirrotta A. , Ricciardi G. 
Published: April 2007

AbstractThe Resilient‐Friction Base Isolator (R‐FBI) stochastic response under severe ground motion modelled as a stationary and non‐stationary zero mean stochastic white noise processes is performed. The moment equation approach is applied and the non‐normal response is obtained by means of a non‐Gaussian closure technique, based on the Gram‐Charlier asymptotic expansion of the response probability density function. Results are compared with the equivalent non linearization technique and with results obtained by means of Monte Carlo simulation.
Towards the use of the hilbert transform and neural intelligence in structural non‐linearity detection
Authors: de Stefano A. , Sabia D. , Sabia L. 
Published: April 2007

AbstractThis paper illustrates a new method for the identification and classification of non linearities in vibrating systems characterised by different non linear stiffness laws. It uses the Hilbert transform in the time domain and introduces the concept of analytical signal of the dynamic response to describe a systems non‐linear behaviour through the representation of motion in a three‐dimensional plane. This procedure generates cyclic paths (referred to as “orbits”) whose shape turns out to be markedly affected by the non‐linear type of behaviour being investigated and can be clearly distinguished from the shapes reflecting different types of non‐linear behaviour. This distinctive feature of the orbits prompted the idea of training hierarchical neural networks to recognise and classify the different shapes. This investigation examines vibrating systems characterised by five different types of non‐linear stiffness.
A scale study of electro‐rheological fluid dampers
Authors: Gordaninejad F. , Bindu R. 
Published: April 2007

AbstractThe goal of this study is to develop a scale analysis for predicting the behavior of cylindrical electro‐rheological fluid (ERF) dampers. Theoretical and experimental scale studies are conducted to investigate the effects of the length of dampers and applied electric field strength on the damping and stiffness coefficients of ERF shock absorbers. It is demonstrated that by employing the results obtained from smaller size prototypes, the damping coefficient of larger size dampers can be estimated with reasonable accuracy.
Design of the nations bank corporate center
Authors: Horvilleur Javier F. 
Published: April 2007

AbstractThe paper describes the structural design of Nations Bank Corporate Center. The topics addressed include the structural system selection process used during preliminary design. A complete description of the reinforced concrete frame is presented with emphasis placed on wind engineering, seismic design and the exterior frame gravity analysis. Differential shortening of core and exterior columns and compensation methods used during construction are presented. Temperature effects are also discussed. Finally, the tower foundation and value engineering changes which resulted in structural savings of over 1.6 million dollars are described. The paper is written for engineers not familiar with the design of Tall Buildings and aims to present in some detail the problems and solutions encountered in the structural design of Nations Bank Corporate Center.
Performance of prefabricated high strength welded wire grids in ductile concrete shear wall boundary elements
Authors: Baumann Hanns U. 
Published: April 2007

AbstractThe performance of a new proprietary concrete reinforcement product, BauMesh, when used as confinement reinforcement in ductile concrete shear walls is discussed.Large material and labor savings are achieved when concrete shear walls are reinforced with these new high strength welded wire ladders positioned at close spacing (3 o.c.) along the length of the longitudinal reinforcement to ensure a non‐brittle ductile response to violent earthquake generated cyclic forces.Design, quality control during manufacture, installation, and the observed performance of a 17‐story San Francisco ductile shear wall building during the Loma Prieta earthquake are discussed.
Seismic eccentrically braced frames
Authors: Tsai K. C. , Yang Y. F. , Lin J. L. 
Published: April 2007

AbstractThis paper provides an overview of the behavior and design of seismic‐resistant eccentrically braced frames (EBFs). Basic characteristics of EBFs are first discussed. The important effects of link length on the performance of EBFs are reviewed. The capacity design concept for EGFs is then addressed. The paper addresses several design issues that appear to have been inadequately considered either in current practice or in the emerging seismic code provisions. Some important observations are provided from pseudodynamic tests of large EBFs and experimental studies of EBF subassemblages with link‐to‐box column connections conducted recently. Future research needs are discussed.
Investigation of current seismic design provisions for reinforced masonry shear walls
Authors: Kariotis John C. , Rahman Auybur , El‐Mustapha Ahmad M. 
Published: April 2007

AbstractCurrent seismic design provisions were investigated to determine if optimum designs resulted from their use. Forty‐two components of recorded ground motions were used for the investigation. These ground motions were recorded in the Imperial Valley in 1940 and 1979. These ground motions were assumed to contain a consistent value of soils factor. The tabulation of the Imperial Valley ground motion revealed that these motions had mean velocity‐acceleration ratios and velocity and acceleration amplification factors that exceeded those determined by prior studies. The investigation confirmed that a modified seismic design formula provided a more consistent dynamic behavior for reinforced masonry shear walls. The investigation also studied the influence of reinforcement ratios of masonry shear walls, the influence of under and excess strength, and the effectiveness of stiffness modification in lieu of strength modification. The investigations supported the conclusions that limitation of the vertical reinforcement ratio increases the displacement ductility of reinforced masonry shear walls, that the current NEHRP Recommended Provisions require a near optimum required strength, and that modification of the stiffness of the shear wall, in lieu of strength modification, is highly beneficial in limiting nonlinear displacements of reinforced masonry shear walls.
Selection of earthquake records for seismic design of tall buildings
Authors: Naeim Farzad 
Published: April 2007

AbstractOne of the most difficult questions that the designer of tall earthquake resistant buildings must address is the determination of the critical earthquake. This is the earthquake ground motion that will drive the structure being designed to its critical response. This paper seeks to help the seismic design engineer address this difficult problem by identification of the severity and damage potential of critical components obtained from a database of more than 5000 records of strong earthquake ground motion. These records virtually represent all the available North American and Hawaiian records written by ground‐level instruments for the period of 1933–1992. Elastic and inelastic response and energy spectra are studied. Spectral data are sorted in terms of the mean value of the response parameter in bracketed bands of the fundamental period.
Behavior state analysis and seismic performance evaluation of a tall masonry building in the Loma Prieta earthquake
Authors: Hart Gary C. , Jaw Jing‐Wen 
Published: April 2007

AbstractA behaviour state analysis is performed on a ten story concrete masonry building that was located in the City of Santz Cruz, which is in the epicentral region of the Loma Prieta earthquake. The building has three types of shear walls (L, T and rectangular) and the behavior state analysis described in the paper first characterizes the expected load deflection response and ductility of each of these shear walls. Then a building system model is developed from these component shear walls models and the load deflection behavior is quantified. This expected load verses deflection behavior of the building is then used to comment on the observed response of the building.
Two stage condensation procedure for free vibration characteristics of framed tube buildings
Authors: Singh Y. , Nagpal A. K. 
Published: April 2007

AbstractAn efficient two stage condensation procedure for the free vibration characteristics of framed tube buildings is presented. In stage 1, the number of d.o.f. is reduced through constraining for which parabolic shape functions are used. In stage 2, the constraints are gradually relaxed using a Gauss—Seidel iterative technique. The procedure is general and can be used for framed tube buildings having any range of member properties and any mass distribution. The method yields accurate results and requires only a fraction of the CPU time and storage locations needed in the standard method. It can be employed to solve frame tube buildings problems of any practical size on microcomputers as well.
A study of earthquake response in a 15‐story reinforced‐concrete frame‐tube model in a shaking table test
Authors: Jiwei Wang , Dajun Ding , Di Zhou 
Published: April 2007

AbstractThrough a series of shaking table tests on a 15‐story regularly hexagonal reinforced‐concrete frame‐tube model of 1:20 scale, the regularities of natural frequencies, the mode shapes and critical damping values of the structure are analysed and the dynamic responses of the structure under one‐dimensional (horizontal or vertical) and two‐dimensional (horizontal and vertical) earthquake waves are studied. In particular, the influences of vertical waves on dynamic response and the failure mechanism of the structure are emphasized in the discussion. Using a finite element program based on a three‐dimensional bar system, the nonlinear dynamic analysis for the test structure is conducted, and finally the calculated and experimental results are compared. Additionally, the influences of vertical earthquake waves on the failure of reinforced‐concrete frame‐tubes is approached using the finite element method and a conclusion consistent with the experimental results is obtained.
Implications of the 1994 northridge earthquake ground motions for the seismic design of tall buildings
Authors: Naeim Farzad 
Published: April 2007

AbstractDesign characteristics of selected 1994 Northridge strong motion records are evaluated. Instrumental, spectral, and energy content attributes of the records are examined. Seismic design implications of these data for tall buildings are discussed. The weaknesses of the current seismic design philosophy in dealing with near‐field strong ground motions, representing significant acceleration pulses, are demonstrated and recommendations for improving both the demand side and the capacity side of current seismic design formulations are provided.
A technique for evaluating the effect of beam‐column joint deformation on the lateral flexibility of steel frame building structures
Authors: Charney Finley A. , Horvilleur Javier F. 
Published: April 2007

AbstractAccurate analysis of steel framed structures requires a careful assessment of the contribution of beam‐column joint deformation to overall structural flexibility. Unfortunately, traditional structural analysis has either ignored the deformations by assuming fully rigid joints, or has approximated the effects by using centerline analysis. Some computer programs use a hybrid technique wherein the beam‐column joint region is assumed to be partially rigid. Due in part to the fact that the preceding analysis technique violate local equilibrium within the joint, the results produced are unrealiable. In this paper, a new analysis technique is presented for beam‐column joint analysis. The method is based on a virtual force analysis of an isolated subassemblage, with local equilibrium within the joint being strictly satisfied. When compared with results of finite analysis of full three dimensional subassemblages, the method has been found to be very accurate.
Interstory drift design and damage control issues
Authors: Mayes Ronald L. 
Published: April 2007

AbstractThis paper addresses post‐earthquake functionality of buildings by focusing on one of the key aspects of damage control design‐interstory drift. It is generally recognized that interstory drift can be used as a measure of expected damage. In order to control damage, the designer must understand the relationship between interstory drift and different levels of damage. Current code provisions for interstory drift, which attempt to address life safety primarily, are reviewed. The limitations of these provisions when applied to damage control design are discussed. An overview of current research on establishing a relationship between interstory drift and damage levels in nonstructural and structural elements is provided.
Use of active mass dampers for wind and seismic control on super‐high‐rise buildings
Authors: Huang King M. , Chou T. J. 
Published: April 2007

AbstractActive mass dampers applied to an 85‐story high‐rise building are investigated in this study. The building was originally designed with an interstory drift ratio under design wind loads of up to 0.004. Stiffening the building through filling the steel box columns with concrete was proposed. However as shown by analysis, the reduction of interstory drift was restricted still within inadmissible range. Active mass dampers were then proposed as an alternative solution. Dampers by two different manufacturers were used, the two systems employing similar mechanisms. Analytical results indicate that both displacement and acceleration of the building are significantly reduced by the incorporation of active mass dampers, however the lack of a reliable backup power system is a major concern. Also, effective control of the structural responses caused by a severe earthquake may still requires further studies.
Continuous pulse and hybrid control of structures
Authors: Pantelides Chris P. , Tzan Shyh‐Rong , Nelson Paul A. 
Published: April 2007

AbstractIn recent years, passive as well as active control methods have been implemented for structural motion reduction of tall buildings in earthquakes. An active control method for the inelastic response of tall buildings is presented. The proposed method of continuous pulse control uses closed‐loop feedback control as a combination of two algorithms. The first is a linear control algorithm‐instantaneous optimal control‐and the second is a pulse control algorithm‐the pulse control algorithm‐which applies a corrective pulse when a prespecified structural velocity threshold is exceeded. The control forces required by active control systems to reduce the seismic response of tall buildings can be quite large. On the other hand, passive control systems such as the viscoelastic dampers do not require external energy for their operation. The possibility of combining viscoelastic dampers and the active bracing system for reducing the required control forces is examined. The combination of passive and active devices improves safety, serviceability and the comfort of the building's occupants.
How to Do More Than Manage Inflation's Effects
Authors: Austin James E. 
Published: April 2007

AbstractAs the countries of Eastern Europe move to become more market‐oriented, they may experience bouts of high infation. This isn't something limited to the Third World or Latin America. Such a possibility, however, should not dampen MNC interest in doing business in any of these parts of the world. In countries subject to inflation, profitability is still possible. Learning to manage its effects can even create competitive advantage.
Strategic partnering in Eastern Europe
Authors: Lewis Tom , Turley Mark 
Published: April 2007

AbstractThere are alternatives to the much‐touted “joint venture” in Eastern Europe. Some of these, such as licensing and cooperation agreements, have actually been available for some time. Others, like wholly owned subsidiaries, mergers, and acquisitions, are in the early stages of development. Clearly, the pace of reform indicates it is time to rethink the conventional wisdom on corporate development in Eastern Europe.