bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of arma models to estimate earthquake ground motion and structural response
Authors: Ólafsson Símon , Sigbjörnsson Ragnar 
Published: April 2007

AbstractThis paper deals with the use of ARMA models in earthquake engineering. Tools and methods applied to strong ground motion are discussed emphasizing simulation of probabilistic earthquake response spectra. The ARMA models are applied to Icelandic earthquake data and a tentative model for Icelandic earthquakes is presented. This model, which is derived using 54 accelerograms, is based on a low‐order, time‐invariant ARMA process excited by Gaussian white noise and amplitude modulated using a simple envelope function to account for the non‐stationary characteristics. This simple model gives a reasonable fit to the observed ground motion. Further, this model produces accurate earthquake response spectra, which, combined with accompanying attenuation and duration formulae, might be useful in earthquake hazard and risk assessment.
The effect of canyon topography on strong ground motion at Feitsui damsite: Quantitative results
Authors: Huang Huey‐Chu , Chiu Hung‐Chie 
Published: April 2007

AbstractThe free‐field accelerograms along Feitsui Canyon are analysed and modelled by a numerical scheme to study the effect of canyon topography. Six strong‐motion accelerometers (SC1–SC6) were deployed along the Feitsui Canyon in 1991. The observations suggest that the amplitude of ground motion at the trough of the canyon is smaller than that on its slopes. The integral equation method is applied to a two‐dimensional model of Feitsui Canyon to study the effects of the canyon topography. We choose the ground motion of SC3 station at the trough of the canyon as the input motion to the model, which is then used to predict the ground motion at the other five stations. The simulated and observed seismograms agree well in displacement and velocity, although the simulated acceleration at high frequency is underestimated. The simple model can reproduce the observed accelerations at all frequencies below 4 Hz.
Dynamic response of rigid tanks with inhomogeneous liquids
Authors: Shivakumar P. , Veletsos A. S. 
Published: April 2007

AbstractA study of the response to horizontal ground shaking of a rigid cylindrical tank containing an inviscid liquid with a continuous vertical variation in density is presented. In addition to the free vibrational sloshing characteristics of the liquid, the responses examined include the vertical displacements at the free surface, and the impulsive and convective components of the hydrodynamic wall pressures and associated tank forces. The equations of motion for the system are formulated for an arbitrary variation in liquid density but the solutions presented are for a density that increases exponentially from top to bottom. Comprehensive numerical data are included which elucidate the underlying response mechanisms and the effects and relative importance of the various parameters involved. The solution for the continuous density variation considered herein is also compared with a previously reported solution in which the liquid was modelled as a multi‐layered, discrete system.
Transient response of single piles under horizontal excitations
Authors: Cheung Y. K. , Tham L. G. , Lei Z. X. 
Published: April 2007

AbstractThe general time‐domain boundary element in cylindrical co‐ordinates developed for the study of wave propagation in a layered half‐space is extended to the response analysis of single piles under horizontal transient excitations. The pile is treated as a beam, and therefore, only the bending stiffness has to be considered in the analysis. As required by the non‐axisymmetric nature of the problem, the soil is modelled by boundary (cylindrical) elements with the vertical, radial and tangential displacements as well as their corresponding tractions as independent variables. The characteristic matrices for the two different types of element can be formed in the usual manner, and they are combined to form the equation of motion for the whole system by virtue of compatibility and equilibrium conditions along the pile‐soil interface. The transient responses of a pile under Heaviside loads are found to converge to the static values. Parametric studies are carried out to reveal the influences of pile‐soil stiffness ratio (Ep/Es) and soil layering.
Seismic response of segmental buildings
Authors: Pan Tso‐Chien , Ling Shih‐Fu , Cui Wei 
Published: April 2007

AbstractThis paper proposes an aseismic design concept in which the superstructure of a base‐isolated building is divided into several segments. Each segment may comprise a few storeys and is interconnected by additional vibrational isolation systems. The dynamic characteristics of the segmental buildings are investigated. The optimum parameters of the vibration isolation systems are determined by minimizing the mean square acceleration response. The seismic response of a typical segmental building subjected to the N—S component of the 1940 El Centro earthquake input is evaluated and compared with the responses of the corresponding fixed‐base and conventional base‐isolated buildings. The comparisons show that, when the superstructure is segmented, while the acceleration response in the superstructure remains as small as that in the conventional base‐isolated building, the displacement across the base isolation system at foundation level is substantially reduced.
Control algorithm for estimating future responses of active variable stiffness structure
Authors: Yamada Kazuhiko , Kobori Takuji 
Published: April 2007

AbstractA control algorithm has been developed for controlling Active Variable Stiffness (AVS) structures. This algorithm analyses information of an observed seismic excitation, estimates the future structural responses and determines how to alter the structure stiffness. An objective structure is assumed to possess N on‐off elements whose states are controlled by the proposed algorithm. That is, at a given moment tk, (1) seismic excitation information is expressed by an Auto Regressive (AR) model as the identification model; (2) future excitation information is predicted using the AR model; (3) future responses due to predicted excitation are estimated; (4) based on the initial condition at tk, the responses of 2N possible structural states from tk, to tk+L are calculated; (5) the state which minimizes the input energy during tL is selected; and (6) immediately after tk, on‐off elements are set up and subjected to the selected states. The effectiveness of the induced algorithm is confirmed by numerical experiments on a model of a three‐storey building under sine and seismic excitations.
Pseudo relative velocity spectra of earthquake ground motion at high frequencies
Authors: Trifunac M. D. 
Published: April 2007

AbstractThe currently available empirical scaling laws for estimation of spectral amplitudes are limited to periods longer than 0–04 s. However, for design of equipment and stiff structures on multiple and distant supports, exposed to strong shaking near faults where peak accelerations can exceed 1g, specification of design ground motions at higher frequencies is required. This paper presents a method for extrapolation of pseudo‐relative velocity spectral amplitudes of strong earthquake shaking to short periods (0–01 < T < 0–04 sec). The extrapolated spectra can be used as a physical basis for defining design spectral amplitudes in this higher‐frequency range.The analysis in this paper implies that for typical strong motion accelerations, particularly on sedimentary sites in California, the peak ground accelerations are projected to be unaffected by frequencies higher than those recorded. Consequently, in California, the high‐frequency pseudo‐acceleration spectra can be approximated from the recorded absolute peak accelerations.
Analytical prediction of experimental building pounding
Authors: Filiatrault André , Wagner Pierre , Cherry Sheldon 
Published: April 2007

AbstractValuable insights on the problem of seismic pounding have been obtained recently from analytical studies. So far, the proposed analytical models have not been validated experimentally. This paper presents the results of shake table tests of pounding between adjacent three‐ and eight‐storey single‐bay steel framed model structures. The pounding response of the frames was measured for various earthquake intensities and initial separations. The experimental results were compared to the predictions resulting from two existing pounding analysis programs. The solution strategy of the first program, SLAM‐2, is based on a modal superposition technique. The second program, PC‐ANSR, is a non‐linear time‐step analysis code in which an elastic gap element has been included. Modelling the pounding effect by elastic gap elements in the two programs produced accurate displacement and impact force results. Amplitudes of short acceleration pulses were not well predicted, however, for practical time‐step increments. Relative rotations between adjacent floors induced grinding contacts which cannot be captured by uni‐axial gap elements.
Reduction of steady‐state forced vibrations of structures with dynamic absorbers
Authors: Klasztorny Marian 
Published: April 2007

AbstractIn the paper the problem of reduction of the steady‐state response of a lightly damped structure to periodic excitation is considered. The primary structure, which has arbitrary distributions of mass, stiffness and damping, is subjected to periodic load with the fundamental frequency varying in a wide range that may include several resonant peaks of the amplitude‐frequency response. A number of passive absorbers are applied simultaneously to the main structure. A general formulation of the dynamic absorber design methodology is presented, based on independent design of conventional absorbers, taking into account the selected modal systems of the original structure and the selected harmonic components of the excitation. In order to cover the losses in the vibration reduction, resulting from the couplings in the primary structure–the set of absorbers system and from the remaining harmonic components of the excitation, the mass of modal dynamic absorbers is increased properly. The methodology developed was verified on several numerical examples; one of them is presented in the study.
Dynamic 3‐D soil–railway track interaction by BEM–FEM
Authors: Mohammadi Mohsen , Karabalis Dimitris L. 
Published: April 2007

AbstractA study on the dynamic response of a railway track is presented via a 3‐D formulation based on the frequency domain Boundary Element Method (BEM) and the Finite Element Method (FEM). The railway track consists of a group of surface, massive, rigid footings resting on a viscoelastic half‐space and connected by an overlaying rail structure. The BEM, employing the full‐space fundamental solutions and quadrilateral elements, is used for the simulation of the elastic half‐space while the FEM is used to model the rigid footings and the rail superstructure. The loading function consists of a set of externally applied, harmonic or transient loads. Frequency as well as transient, by way of FFT, results are presented for various modes of vibration. Various numerical studies assess the through‐the‐soil interaction of the adjacent footings, the influence of soil damping, the effect of the overlaying structure on the frequency content of the system, and the effective simulation of an infinitely long railway track by a truncated one.
Earthquake ground motion characteristics and seismic energy dissipation
Authors: Sucuoǧlu Haluk , Nurtuǧ Alphan 
Published: April 2007

AbstractThe sensitivity of seismic energy dissipation to ground motion and system characteristics is assessed. It is found that peak ground acceleration, peak ground velocity to acceleration (V/A), dominant period of ground excitation and effective response duration are closely correlated with the energy dissipated by a SDOF system. Ductility ratio and damping ratio have no significant influence on the energy dissipation. An energy dissipation index is proposed for measuring the damage potential of earthquake ground motion records which includes the effects of basic excitation and response characteristics contributing to the seismic energy dissipation. The proposed index is compared with several intensity measures for the set of 94 ground motion records considered in the study.
Prediction of seismic energy dissipation in SDOF systems
Authors: Nurtuǧ Alphan , Sucuoǧlu Haluk 
Published: April 2007

AbstractA simple analytical procedure is developed for calculating the seismic energy dissipated by a linear SDOF system under an earthquake ground excitation. The ground excitation is specified by its pseudo‐velocity spectra and effective duration whereas the SDOF system is defined by its natural period of vibration and viscous damping ratio. However, the derived relationship for the energy dissipation demand under an earthquake excitation is sensitive neither to the viscous damping ratio nor the ductility ratio when the SDOF system undergoes inelastic response. Accordingly, the proposed relationship can be employed in an energy‐based seismic design procedure for determining the required energy dissipation capacity of a structural system.
Seismic evaluation of concrete dams via continuum damage models
Authors: Cervera Miguel , Oliver Javier , Faria Rui 
Published: April 2007

AbstractIn this paper a general methodology for the analysis of large concrete dams subjected to seismic excitation is outlined. It is valid both for gravity dams (2D representation) and arch dams (3D representation). The method allows for non‐linear material behaviour of the dam, ‘transparent fictitious boundaries’ for dealing properly with in‐coming and out‐going seismic waves, and an efficient procedure to deal with dam‐soil‐fluid interaction. The mechanical behaviour of concrete is modelled using an isotropic damage model which allows for tension and compression damage, and exhibits stiffness recovery upon load reversals. Emphasis is placed in the treatment of fluid‐structure interaction, regarding both formulation and efficiency aspects. A gravity dam and an arch dam are analysed subjected to artificially generated earthquakes of different intensities, and the results are used to study the degree of (un)safety of the dams.
Bidding behaviour and electricity market simulation
Authors: Chandarasupsang T. , Galloway S. , Burt G. , McDonald J. , Siewierski T. 
Published: April 2007

AbstractTo trade effectively and profitably in new electricity market structures, participants need to identify how best to use information available to them. In many cases only incomplete information will be available for short‐term planning, trading and decision‐making. This paper simulates a group of generators who adapt bidding behaviours in different segments of liberalised electricity markets based on historic market information, observed strategies and their view of other market participants. Results show that even in the incomplete information case efficient bidding strategy for market participants can be identified. Specifically, this paper presents some key findings from an active electricity market and utilises them within an electricity market simulation. The benefit of market simulation for participants is identified and reported. Copyright © 2007 John Wiley & Sons, Ltd.
Automatic correction of the systematic error on AGC regulators due to tie‐line losses
Authors: Ćalović M. S. , Stefanov P. Č. , Obradović N. M. 
Published: April 2007

AbstractThis paper considers the problems of automatic correction of systematic error appearing in conventional Automatic Generation Control (AGC) regulators, due to the ignorance of power losses, normally existing on all inter‐area tie‐lines. This is achieved with modification of input signals on AGC area regulators (the Area Control Error, ACE) by introducing the tie‐line losses, calculated by simple measurements of all area tie‐line flows at both (sending and receiving) line ends. The paper presents the theoretical development of the idea and proposes the new, modified, but cheap AGC scheme, proven by simulation tests on the example of two‐area interconnection. The benefit of applying the proposed AGC regulators is the better system performance and less frequent need for the synchronous time and inadvertent interchange error corrections. Copyright © 2007 John Wiley & Sons, Ltd.
Time‐simultaneous prediction band for a time series
Authors: Kolsrud Dag 
Published: April 2007

AbstractI propose principles and methods for the construction of a time‐simultaneous prediction band for a univariate time series. The methods are entirely based on a learning sample of time trajectories, and make no parametric assumption about its distribution. Hence, the methods are general and widely applicable. The expected coverage probability of a band can be estimated by a bootstrap procedure. The estimate is likely to be less than the nominal level. Expected lack of coverage can be compensated for by increasing the coverage in the learning sample. Applications to simulated and empirical data illustrate the methods.  Copyright © 2007 John Wiley & Sons, Ltd.
Single‐season heteroscedasticity in time series
Authors: Tripodis Yorghos , Penzer Jeremy 
Published: April 2007

AbstractWe consider seasonal time series in which one season has variance that is different from all the others. This behaviour is evident in indices of production where variability is highest for the month with the lowest level of production. We show that when one season has different variability from others there are constraints on the seasonal models that can be used; neither dummy and trigonometric models are effective in modelling this type of behaviour. We define a general model that provides an appropriate representation of single‐season heteroscedasticity and suggest a likelihood ratio test for the presence of periodic variance in one season.  Copyright © 2007 John Wiley & Sons, Ltd.
Target redemption notes
Authors: Chu Chi Chiu , Kwok Yue Kuen 
Published: April 2007

AbstractThe target redemption note is an index‐linked note that provides a guaranteed sum of coupons (target cap) with the possibility of early termination. In a typical structure, the coupons are calculated based on an inverse floating, London Interbank Offered Rate/Euro Interbank Offered Rate (LIBOR/Euribor) formula. Once the accumulated amount of coupons has reached the prespecified target cap, the note will be terminated with final payment of the par. The knock‐out criterion depends on a path‐dependent state variable defined by the running accumulated coupon sum. In some simplified cases, we manage to obtain a closed form valuation formula for the note value. We propose several numerical schemes for pricing the note under the one‐factor and two‐factor short rate models. Pricing behaviors of the target redemption note are also explored. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27:535–554, 2007
Optimal selection of markers for validation or replication from genome‐wide association studies
Authors: Greenwood Celia M.T. , Rangrej Jagadish , Sun Lei 
Published: April 2007

AbstractWith reductions in genotyping costs and the fast pace of improvements in genotyping technology, it is not uncommon for the individuals in a single study to undergo genotyping using several different platforms, where each platform may contain different numbers of markers selected via different criteria. For example, a set of cases and controls may be genotyped at markers in a small set of carefully selected candidate genes, and shortly thereafter, the same cases and controls may be used for a genome‐wide single nucleotide polymorphism (SNP) association study. After such initial investigations, often, a subset of “interesting” markers is selected for validation or replication. Specifically, by validation, we refer to the investigation of associations between the selected subset of markers and the disease in independent data. However, it is not obvious how to choose the best set of markers for this validation. There may be a prior expectation that some sets of genotyping data are more likely to contain real associations. For example, it may be more likely for markers in plausible candidate genes to show disease associations than markers in a genome‐wide scan. Hence, it would be desirable to select proportionally more markers from the candidate gene set. When a fixed number of markers are selected for validation, we propose an approach for identifying an optimal marker‐selection configuration by basing the approach on minimizing the stratified false discovery rate. We illustrate this approach using a case‐control study of colorectal cancer from Ontario, Canada, and we show that this approach leads to substantial reductions in the estimated false discovery rates in the Ontario dataset for the selected markers, as well as reductions in the expected false discovery rates for the proposed validation dataset. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
Affected relative pairs and simultaneous search for two‐locus linkage in the presence of epistasis
Authors: Schaid Daniel J. , McDonnell Shannon K. , Carlson Erin E. , Thibodeau Stephen N. , Ostrander Elaine A. , Stanford Janet L. 
Published: April 2007

AbstractIt is commonly believed that multiple interacting genes increase the susceptibility of genetically complex diseases, yet few linkage analyses of human diseases scan for more than one locus at a time. To overcome some of the statistical and computational limitations of a simultaneous search for two disease susceptibility loci in the presence of epistasis, we developed new score statistics to simultaneously scan for two disease susceptibility loci in pedigree data. These model‐free score statistics are based on developments for model‐free maximum lod scores, which in turn are based on variance components for indicators of disease status. To overcome reduced power caused by many parameters in the general two‐locus model, we impose constraints on ratios of variance components, much like those used for robust single‐locus linkage statistics (e.g., minimax constraints). The resulting three‐degree of freedom score statistic, constrained as a one‐sided multivariate test, can be computed rapidly, making simultaneous search feasible for human genetic linkage studies. Furthermore, using recent developments to rapidly compute simulation P‐values for score statistics, it is feasible to empirically evaluate the statistical significance of the proposed score statistics. Application of these methods to two large studies of the genetic linkage of prostate cancer illuminates their strengths and limitations. The results provide weak suggestions for linkage of several pairs of chromosomal regions (chromosome pairs 1–21, 3–13, 5–9, and 14–19), all of which showed stronger linkage signals when the score statistics accounted for epistasis. These novel score statistics should prove useful for linkage studies of other complex human diseases. Genet. Epidemiol. 31, 2007. © 2007 Wiley‐Liss, Inc.