bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnitude assessment of northwestern european earthquakes
Authors: Ambraseys N. N. 
Published: March 2007

AbstractA homogeneous and internally consistent body of regional magnitudes is needed not only for the statistical study of seismicity but also for the modelling of seismic sources and for the hazard assessment of engineering sites. Also the assessment of the design ground motions for engineering projects requires homogeneous magnitude estimates. The nature of the available data for U.K. and Northwestern European earthquakes, and of the events themselves, is such that we are concerned with the assessment of magnitudes at the lower end of the scale, and thus great importance focuses on the uniform calculation of magnitudes within a relatively narrow range of M values. The purpose of this study is to present the uniform re‐assessment of magnitudes for British and Northwestern European earthquakes for the period 1900 to 1984. It is shown that, for the larger events, surface‐wave magnitudes can be estimated uniformly and that neither a period constraint at 20 seconds nor distance effects for the regional conditions considered appear to play an important role. For smaller events, crustal phases at short distances have been used to derive calibration curves for a magnitude which, at larger distances and longer periods would fit the magnitude scale of surface waves.
Dynamic response of bilinear asymmetric structures
Authors: Syamal Pradip K. , Pekau O. A. 
Published: March 2007

AbstractThe inelastic behaviour of eccentric single‐storey building structures subjected to sinusoidal ground excitation is examined. The Kryloff‐Bogoliuboff method is employed to provide approximate solutions in the amplitude‐frequency domain. Structural resisting elements are assumed to exhibit bilinear hysteretic behaviour and coupled response is investigated in terms of both system response as well as individual element ductility requirements. In addition to demonstrating the well‐known softening property inherent in yielding systems, the importance of the principal parameters governing coupled response is evaluated in a consistent parametric fashion. Within the context of earthquake resistant building design, the results indicate the absence of amplified response when torsional and translational frequencies are close, in contrast to the much emphasized observation of internal resonance for linear elastic structures. Equally important, structural elements located on the stiff edge of eccentric buildings are found to be only marginally affected by the magnitude of the eccentricity, thus indicating that seismic building codes which reduce design requirements for these elements underestimate actual behaviour substantially.
Intensity‐attenuation and magnitude‐intensity relationships for northwest european earthquakes
Authors: Ambraseys N. 
Published: March 2007

AbstractThis study shows that, for Northwest Europe, an intraplate region of subdued seismicity, a comparatively simple attenuation model is adequate to predict quite accurately the fall‐off of intensity with distance. The analysis shows that focal depths determined from macroseismic data are confined in the upper 25 km, and that shallow shocks attenuate far more rapidly than deeper events. There is no evidence for a regional variation of the absorption coefficient, which, together with the coefficient of geometric spreading, is a function of depth. Also, the intensity factor b, which is usually taken to be equal to 3, is a variable and a function of the energy absorption at the epicentre. It is shown that magnitudes can be predicted accurately by use of one or preferably by more isoseismal radii calibrated against re‐assessed instrumental magnitudes.
Response of jointed arches to earthquake excitation
Authors: Hall John F. , Dowling Michael J. 
Published: March 2007

AbstractAn efficient method for accurately modelling the gradual opening and closing of joints in two‐dimensional slabs and arches has been devised. The method is used in computing the earthquake response of an arch which is a representative horizontal cross‐section of a concrete arch dam. Responses of the arch with and without joints are compared to assess the effect of joint opening. An extension to three‐dimensional arch dams is proposed.
Determination of parameters for a model for the cyclic behaviour of interfaces
Authors: Drumm E. C. , Desai C. S. 
Published: March 2007

AbstractThe cyclic shear stress‐deformation response of dry sand‐concrete interfaces is described using a modified form of a Ramberg–Osgood (R‐O) model. The model permits the description of the interface secant stiffness as a function of the normal stress, shear stress, sand density and number of loading cycles. Stiffening behaviour, or an increase in secant shear stiffness with number of cycles, may be represented, as well as degradation behaviour.Typical results from a series of cyclic direct shear tests are presented. A methodology is described by which the parameters for the (R‐O) model can be determined from the laboratory shear tests, and the functional forms of the parameters for the sand‐concrete interface are provided.The model is verified by predicting the response of two displacement controlled laboratory tests that were used for the determination of the model parameters. An additional verification is presented in which the response is predicted for a test not used in the parameter determination. The model is shown to simulate satisfactorily the cyclic response, including the effect of number of loading cycles.
Limiting performance of shock isolation systems by a modal approach
Authors: Pilkey Walter D. , Kitis Levent 
Published: March 2007

AbstractThe problem of determining the limiting performance of vibrating systems under shock loading is solved by replacing portions of the system by control forces which can represent any design. For the class of problems treated here, the performance index and the constraints are linear combinations of system response variables such as displacements, velocities and accelerations. Furthermore, the equations of motion are linear, so that it is possible to formulate the optimization procedure as a linear programming problem. In expressing the performance index and the constraints as linear functions of the unknown control forces, a modal approach is used to simplify and improve previous treatments of this problem. In spite of these linearity requirements, the control forces are not required to be linear functions of the response variables.
Attenuation of modified mercalli intensity in New Zealand earthquakes
Authors: Dowrick David J. 
Published: April 2007

AbstractThis paper describes a comprehensive study of the attenuation of Modified Mercalli intensity in New Zealand earthquakes, which has resulted in significantly different and new findings when compared with those of earlier work. The current study used recently revised magnitudes for the 30 events in the carefully selected data set. Magnitudes ranged from ML = 5.0 to Ms = 7.8. Special effort was also put into establishing the depths of the events, which ranged from very shallow to 65 km. An expression of a form also used in peak ground acceleration attenuation studies was adopted, I = a + bM + cr + dlog10r with r being taken as the mean distance from the centre of the fault rupture surface to each isoseismal. A two‐step stratified regression analysis was used because it results in more realistic estimates of standard errors, although its mean curves were virtually the same as those derived from the standard one‐step method. It was found possible to model accurately the attenuation of the deepest events from regressions of the data of the shallowest events, but the inverse was not true. In a study of the influence of source mechanisms it was found that the attenuation was the same for events with normal and strike‐slip faulting. In contrast, events with reverse fault mechanisms were found to have higher intensities (for the same M and r) than normal and strike‐slip events, by a factor corresponding to that found by Campbell in a study of peak ground accelerations, although the statistical test was narrowly short of the conventional significance level.
The seismic behaviour of cross‐braced steel frames
Authors: Wijanto L. S. , Moss P. J. , Carr A. J. 
Published: April 2007

AbstractAnalytical studies on the inelastic behaviour of concentrically braced steel frames for low‐rise buildings are described in this paper. The bracing members which provide energy dissipation were used to provide information on the ductility levels that are likely to occur under differing levels of earthquake excitation.An indication of the relative performance of cross bracing is provided in terms of suitable SM values for use in the seismic provisions of New Zealand loadings code NZS 4203.
Response spectral ratios
Authors: Rosenblueth Emilio , Arciniega Alejandra 
Published: April 2007

AbstractAt many sites on soft ground, spectral ratios (ratios of smoothed Fourier amplitude spectral ordinates at the site to those at a station on firm ground) for distant earthquakes are little sensitive to focal mechanism and coordinates and to magnitude. Spectral ratios furnish directly expected Fourier amplitude spectral ordinates at the site of interest. The corresponding response spectra can be estimated through the use of random vibration theory. This step is obviated by resorting directly to ratios of response spectral ordinates. Through comparisons for several sites on the Valley of Mexico we find that these ratios are as stable as those of Fourier amplitude spectral ordinates.
Attenuation of peak ground acceleration in central california from observations of the 17 october, 1989 Loma Prieta earthquake
Authors: Niazi M. , Mortgat C. P. , Schneider J. F. 
Published: April 2007

AbstractThe strong ground motion produced by the 17 October, 1989 Loma Prieta earthquake in northern California was recorded at over 100 stations. Accelerograms were generated at sites with significantly different geology, including land fill and soft sedimentary soil sites. In this study, the attenuation characteristics of the peak vertical and horizontal ground accelerations are studied for freefield recording conditions within 100 km of the source by the application of a non‐linear multi‐regression procedure. Two sets of attenuation models for weighted and unweighted observations are compared with those reported by other investigators for this earthquake and for regional and worldwide data. The peak ground acceleration (PGA) observations for this earthquake exceed previous predictions of standard attenuation models, particularly beyond 30 km (approximately 60 percent at 50 km). Higher attenuation of the vertical component compared to the horizontal is confirmed.The regression considers site geology as an independent parameter. Soil sites display as much as 23 per cent amplification relative to rock sites for horizontal PGA and as much as 40 per cent for vertical PGA. Amplification of the ground motion at sites characterized by soft soil geology is examined by comparing the recorded PGA with the corresponding prediction at sites underlain by stiff soil. Eight of ten of the soft soil sites display significant amplification relative to stiff soil sites (as much as 300 per cent for horizontal and 200 per cent for vertical components). Particular attention is paid to the so‐called anomalous observations at distances beyond 50 km. The anomalous observations between 50 and 80 km may be attributed to various factors such as geology, basic geometry, azimuthal dependence, source mechanism and normal scatter of observations.
Inclusion of higher modes in the analysis of non‐classically damped systems
Authors: Kulkarni Shrikrishna M. , Ng S. F. 
Published: April 2007

AbstractA time‐integration procedure for dynamic analysis of non‐classically damped systems, in which high‐frequency modes play a significant role, is suggested. This procedure is an extension of Clough and Mojtahedi's1 method. Clough and Mojtahedi suggested integration of the transformed coupled equations of motion where the transformation is done using a truncated set of undamped mode‐shapes. The proposed extension consists in adding the response of all the higher modes through a quasistatic analysis. Approximations involved in using such a procedure are examined. Numerical results presented indicate that the proposed extension leads to a significant improvement over Clough and Mojtahedi's method.
Assessment of the accuracy of the newmark method in transient analysis of wave propagation problems
Authors: Wang Yue‐Cong , Murti Viriyawan , Valliappan Somasundaram 
Published: April 2007

AbstractThe Newmark average acceleration method is non‐dissipative and unconditionally stable, but its accuracy in transient analysis of wave propagation problems depends not only on the spatial discretization but also on the temporal discretization. It has been found that the effects of spatial and temporal discretization when considered separately as commonly done, are far from adequate for most transient analysis. A better criterion manipulating the interdependent relationship between mesh size and time‐step magnitude is imperative to achieve sufficiently accurate results of analysis. In this paper, the accuracy of the Newmark method is investigated by considering the two basic sources of errors, namely, numerical amplitude dissipation and velocity dispersion. The effects of both spatial and temporal discretizations are considered. A new technique to describe the characteristics of various frequency spectra is established. A criterion for mesh design and the selection of time‐step magnitude is also proposed based on the combined effects of the amplitude dissipation and velocity dispersion. The efficiency and effectiveness of the proposed criterion are demonstrated using two one‐dimensional wave propagation problems. A two‐dimensional application shows that this criterion is equally applicable to multidimensional problems.
Stochastic earthquake response of secondary systems in base‐isolated structures
Authors: Chen Yu , Ahmadi Goodarz 
Published: April 2007

AbstractThis paper studies the stochastic responses of secondary systems in base‐isolated shear beam structures. A number of base isolation systems such as the laminated rubber bearing (LRB), the resilient‐friction base isolator (R‐FBI) with or without sliding upper plate, and the EDF system are considered. The stochastic models for the El Centro 1940 and the Mexico City 1985 earthquakes which preserve the non‐stationary evolutions of amplitude and frequency content of ground accelerations are used as earthquake excitations. The technique of equivalent linearization is utilized and the mean‐square response statistics of secondary systems and primary structure are evaluated. The accuracy of the linearization scheme is verified by comparison with the Monte Carlo simulation results. Statistically estimated peak responses of the secondary system are evaluated and the results are compared with the response spectra for actual earthquake accelerograms. It is shown that the use of base isolation systems, generally, provides considerable protection for structural contents. In particular, the LRB system is remarkably effective in reducing responses of secondary systems. Results for the Mexico City earthquake show that the base‐isolated structures are sensitive to long period ground excitations.
A modified static procedure for the design of torsionally unbalanced multistorey frame buildings
Authors: Chandler A. M. , Duan X. N. 
Published: April 2007

AbstractSeismic building codes include design provisions to account for the torsional effects arising in torsionally unbalanced (asymmetric) buildings. These provisions are based on two alternative analytical procedures for determining the design load for the individual resisting structural elements. A previous study has shown that the linear elastic modal analysis procedure may not lead to conservative designs, even for multistorey buildings with regular asymmetry, when such structures are excited well into the inelastic range of response. The equivalent static force procedure as recommended by codes may also be deficient in accounting for additional ductility demand in the critical stiff‐edge elements. This paper addresses the non‐conservatism of existing static torsional provisions and examines aspects of element strength distribution and its influence on inelastic torsional effects. A recommendation is made for improving the effectiveness of the code‐type static force procedure for torsionally unbalanced multistorey frame buildings with regular asymmetry, leading to a design approach which estimates conservatively the peak ductility demand of edge elements on both sides of the building. The modified approach also retains the simplicity of existing code provisions and results in acceptable levels of additional lateral design strength. It has recently been adopted by the new Australian earthquake code, which is due to be implemented early in 1993.
Cone models for nearly incompressible soil
Authors: Meek Jethro W. , Wolf John P. 
Published: April 2007

AbstractCones can be used to model soil in a unified strength‐of‐materials approach. For the vertical and rocking motions involving predominantly compressional‐extensional deformation, the corresponding dilatational wave velocity tends to infinity for Poisson's ratio approaching 1/2. Based on the rigorous solution for the dynamic stiffness of a rigid disk for all frequencies, whereby the partition of the power among P‐, S‐ and Rayleigh waves is also discussed, two special features are necessary for the vertical and rocking motions for nearly incompressible soil with Poisson's ratio between 1/3 and 1/2: (1) The appropriate wave velocity is selected as twice the shear wave velocity and not as the dilatational wave velocity; (2) A trapped mass which increases linearly with Poisson's ratio is introduced. The trapped mass can be assigned to the base mat, allowing the cone model to be constructed in the same way for all Poisson's ratios. The realization of cone models for surface foundations on a homogeneous half‐space and on a layer on a flexible half‐space and for embedded and pile foundations is addressed.
Why cone models can represent the elastic half‐space
Authors: Meek Jethro W. , Wolf John P. 
Published: April 2007

AbstractIn lieu of the rigorous elastodynamical approach, many problems in foundation dynamics may be solved quite accurately via simple cone models of the soil. Although these cone models are amenable to very simple analysis, they have not yet been widely accepted in engineering practice. The reservations against their use are possibly due to the fact that cones are based on non‐rigorous strength‐of‐materials assumptions, they neglect large portions of the half‐space, and cannot represent Rayleigh surface waves. These potential objections are investigated step by step and proven to be unfounded. It turns out that cone models indeed incorporate and provide valuable insight into all the salient features of rigorous solutions; the aspects omitted by cones are revealed to be of minor physical importance.
Damage costs for commercial and industrial property as a function of intensity in the 1987 Edgecumbe earthquake
Authors: Dowrick David J. , Rhoades David A. 
Published: April 2007

AbstractThis paper describes an analysis of damage costs to commercial and industrial property, including buildings (all low‐rise), their contents, equipment and stock, in the Ms = 6.6 Edgecumbe New Zealand earthquake of 2 March 1987. The damage costs were converted to damage ratios by dividing by the value of the relevant property item. For the MM7 and MM9 intensity zones, the mean values and statistical distributions of these damage ratios were then found, the lognormal distribution fitting well.For all commercial and industrial buildings in the MM intensity IX zone (centroid MM9‐4) the mean damage ratio was 0.076. The mean damage ratios were generally much smaller than estimated in previous studies. The buildings were all low‐rise. There was no correlation between building and equipment damage ratios on a building by building basis. Considering dates of construction, it appears that mean damage levels at MM9 have not changed significantly for postcode buildings through changes in design standards up to the 1980s.
An internal variable approach applied to the dynamic analysis of elastic–plastic structural systems
Authors: Rajgelj S. , Amadio C. , Nappi A. 
Published: April 2007

AbstractDiscrete elastic–plastic systems subjected to dynamic load conditions are considered and properties related to an implicit time‐integration scheme are discussed on the basis of an internal variable formulation. The material models accounted for are quite general: elastic–perfectly plastic and elastic–plastic (subjected to linear or non‐linear, kinematic or isotropic hardening). The internal variable approach adopted in the paper leads easily to extremum theorems from which convergence properties of convenient time‐integration schemes immediately follow. Next, taking account of the stabilising effect due to inertial and damping forces, it is shown how the above results can be extended to the case of softening (again linear or non‐linear, kinematic or isotropic). Finally, some numerical examples are given and an extension to damage models is envisaged.
Dynamic impedances of a weakly anelastic medium
Authors: Sienkiewicz Zbigniew 
Published: April 2007

AbstractApproximate formulas are derived to evaluate in the frequency domain the dynamic impedances of a weakly anelastic medium based on its pure elastic behaviour. The correspondence principle is applied to the elastic solution of a boundary‐value problem followed by the expansion of the anelastic solution in a Taylor series about the elastic state. Taking the magnitude of material damping into account (small damping) only the first two terms of the Taylor series have been used. The derivatives of first order in the expansion can be determined by the central difference approximation; this requires only the evaluation of differences between neighbouring elastic solutions.
An analytical solution for the probabilistic response of sdof non‐linear random systems subjected to variable amplitude cyclic loading
Authors: Manzocchi G. M. E. , Chryssanthopoulos M. , Elnashai A. S. 
Published: April 2007

AbstractDesign for a specific ductile failure mode is assuming a rǒle of increasing importance for earthquake‐resistant structures. This necessitates an accurate assessment of the distribution of overstrength in the structure, in order that the predefined failure mode can be realized. Consequently, the variability of the response for a given variability in the salient material properties, such as yield strength for steel structures, should be assessed and accounted for. In this paper an analytical method is proposed for the evaluation of the probability density function of the response of a single‐degree‐of‐freedom hysteretic system with random parameters subject to a variable amplitude cyclic load history. A simple algorithm is derived which may be used to obtain the system response as a function of the system parameters. This response function may then be used to evaluate the displacement response probability density function when given the probability density function of the system parameters. Results derived from this procedure are verified against Monte Carlo simulation. It is shown that accurate response statistics are obtained at a fraction of the computing cost of simulation techniques.