bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic behaviour of building‐foundation systems
Authors: Veletsos Anestis S. , Meek Jethro W. 
Published: March 2007

AbstractA discussion of the effects of soil‐structure interaction on the dynamic response of linear structures which respond as single‐degree‐of‐freedom systems in their fixed‐base condition is presented. The structures are presumed to be supported at the surface of a homogeneous, elastic halfspace and to be excited at the base. The free‐field ground motions investigated include a harmonic motion, a relatively simple pulse‐type excitation and an actual earthquake record. Comprehensive response spectra are presented for a range of the parameters defining the problem, and the results are used to assess the accuracy of a simple, approximate method of analysis in which the system is represented by a viscously damped, simple oscillator. Special attention is given to defining the conditions under which the interaction effect is of sufficient importance to warrant consideration in design. The method of analysis used to obtain the numerical data reported herein is reviewed only briefly, the emphasis of the paper being on the interpretation of the results.
A comparative study of bounding techniques in dynamic shakedown of elasto‐plastic structures
Authors: Corradi Leone , Nova Roberto 
Published: March 2007

AbstractTwo conceptually different procedures to obtain upper bounds to displacements and deformations developed in the dynamic evolution of elasto‐plastic structures are considered. Computationally, both methods require the dynamic analysis of a linear system and a sequence of constrained optimization problems, each roughly analogous to a limit analysis procedure in the quasi‐static range, with a substantial saving in effort when compared to an incremental analysis of the plasto‐dynamic response. A discrete model for frames is proposed and the two approaches are reformulated in a convenient matrix form. The approaches are then compared on the basis of the information needed (total or plastic displacements, deformations, dissipated energy), of the usefulness of results obtained and of the computational effort involved. The results seem to indicate the practical usefulness of these techniques and encourage the extension of the study to broader classes of structures.
Scattering of plane sh waves by a semi‐elliptical canyon
Authors: Wong H. L. , Trifunac M. D. 
Published: March 2007

AbstractIn this paper we analyse the two‐dimensional scattering and diffraction of plane SH waves by a semi‐elliptical canyon. The exact series solution of the problem, for general angle of incidence of the plane SH waves, has been used to examine the dependence of surface amplifications inside and near the canyon. The nature of ground motion has been found to depend on two key parameters: (a) The angle of incidence. (b) The ratio of the canyon width to the wave length of incident SH waves.For short incident waves surface displacement amplitudes change rapidly from one point to another, while for the long waves and shallow canyons displacement amplitudes display only minor departure from the uniform half‐space amplification of 2. For shallow canyons and long incident waves, the angle of incidence introduces only minor changes into the overall behaviour of surface amplitudes. For deep canyons and nearly grazing incidences, a prominent shadow zone is realized behind the canyon.
Ground vibrations due to seismic detonation in oil exploration
Authors: Awojobi A. O. , Sobayo O. A. 
Published: March 2007

AbstractPrevious works on this subject deal mainly with establishing an empirical relationship between the extent of the vibration at the building site (measured by the peak particle velocity), the distance of the building from the explosive, the energy content of the explosive and the frequency of detonating the explosives. These works are mainly limited to cases where the explosives are placed on the surface. However, the practical case requires that the explosive is considered to be buried, either on the sea‐bed in offshore operations or underground in land explorations. This practical case has hitherto received little attention.The present work records an empirical relation based on field tests in Mid‐Western and Rivers States of Nigeria. The depth of the buried explosive is now introduced as an additional parameter and the empirical relation shows its effect, along with the above parameters, on the extent of vibrations at the surface. An interesting, and rather unexpected, stationary point is consistently observed in the variation of peak particle velocity at the surface as the depth of the buried explosive increases while other parameters are kept constant.
Earthquake analysis of axisymmetric towers partially submerged in water
Authors: Liaw C.‐Y. , Chopra Anil K. 
Published: March 2007

AbstractA method for analysis of response of axisymmetric towers partly submerged in water to earthquake ground motion is presented. The tower is idealized as a finite element system. The hydrodynamic terms are determined by solving the Laplace equation, governing the dynamics of incompressible fluids, subject to appropriate boundary conditions. For cylindrical towers, these solutions are obtained as explicit mathematical solutions of the boundary value problems; whereas they are obtained by the finite element method in case of towers with non‐cylindrical outside surface. The response to earthquake ground motion is determined by step‐by‐step integration of the equations of motion. Analyses of two actual intake towers are presented to illustrate results obtained by this method. The small computation times required for these analyses demonstrate that the method is very efficient. The effectiveness of this formulation lies in avoiding the analysis of a large system by using a substructure approach and in exploiting the important feature that structural response to earthquake ground motion is essentially contained in the first few modes of vibration of the tower with no surrounding water.
Dynamic behaviour of structures with embedded foundations
Authors: Bielak Jacobo 
Published: March 2007

AbstractA study of the dynamics of building‐soil interaction is presented that includes embedding of the foundation and material damping. By considering buildings on rigid footings embedded into linear elastic soil with hysteretic damping, it is shown that the earthquake response of the building‐foundation model may be found from the response to modified excitation of equivalent one‐degree‐of‐freedom linear, viscously damped oscillators resting on rigid ground. For a single‐storey building approximate formulas are developed for the modified natural frequency and damping ratio.Results show that the natural frequency and damping in the system increase with embedding. Effective damping also increases with internal friction in the soil. Ignoring these two factors may underestimate considerably the effective natural frequency and damping in the system. In spite of additional sources of energy dissipation provided by the soil, damping in the equivalent oscillator may be greater or smaller than that corresponding to the superstructure alone, depending upon the system parameters.For lightly damped superstructures, the peak amplitude of the steady‐state overturning moment at the base of a building supported on flexible soil is significantly smaller than that corresponding to rigid ground. This result has practical implications for earthquake design.
The effect of coulomb damping on multidegree of freedom elastic structures
Authors: Mayes R. L. , Mowbray N. A. 
Published: March 2007

AbstractThis paper is based on the premise that the damping mechanism of a multidegree of freedom structure can be represented by viscous and coulomb dampers. A closed form solution for the structure subjected to a sinusoidal forcing function is presented. The solution is used as the basis of a method for determining relative amounts of viscous and coulomb damping from vibration tests. The method was applied to the results of a series of vibration tests on a five storey reinforced concrete structure and approximate values of viscous and coulomb damping obtained. A comparison of the effect of various combined damping values on the earthquake response of the structure was made. It was concluded that the use of the equivalent viscous damping concept to approximate the combined effect of viscous and coulomb damping results in a low estimate of the elastic response of the structure.
Hysteretic dampers for earthquake‐resistant structures
Authors: Skinner R. I. , Kelly J. M. , Heine A. J. 
Published: March 2007

AbstractThe earthquake resistance of many structures can be increased by the inclusion of special components which act as hysteretic dampers. During moderately severe earthquakes these dampers act as stiff members which reduce structural deformations, while during very severe earthquakes the dampers act as energy absorbers which limit the quasi‐resonant build‐up of structural deformations and forces.The hysteretic dampers are not required to withstand the main structural loads, and may therefore be optimized for their required stiffness and energy‐absorbing features. On the other hand, the main structural components no longer require large energy‐absorbing capacities and they may therefore be optimized for their required stiffnesses and load‐bearing features.For many structures this separation of component functions should lead to increased reliability at a lower initial cost. Under earthquake attack structural damage should be reduced. Non‐structural damage should be lower during moderately severe earthquakes, and for certain types of structure it should also be lower for very severe earthquakes.Various ways in which hysteretic dampers may be utilized in structures are discussed briefly.The development of several types of high‐capacity, low‐cost hysteretic damper, suitable for use in structures, is described. The dampers utilize solid steel beams deformed plastically in various combinations of torsional, flexural and shear deformations.
A practical system for isolating structures from earthquake attack
Authors: Skinner R. I. , Beck J. L. , Bycroft G. N. 
Published: March 2007

AbstractThe recent development of a range of hysteretic energy absorbers permits practical shock isolation systems to be incorporated in the bases of a wide range of structures. This isolation gives reduced earthquake loads which may be resisted by the normal lateral strength of the structure. Hence a plastic reserve of earthquake resistance is no longer essential.A wider choice of architectural and structural forms is available with such an isolation system. The structures may be designed to prevent structural and non‐structural damage with a high degree of reliability.The special hysteretic dampers limit the lateral movement of the base of a structure to a few inches. With these small movements the lateral flexibility required for an isolating system can be conveniently provided, for many structures, by rubber bearings.
Additional note on the effect of soil on structural response
Authors: Novak Milos 
Published: March 2007

AbstractThe previous paper on this subject, Reference 1, is complemented here to include one additional effect of soil on structural response. This effect is the modification of the original structural damping, estimated under the assumption of rigid foundation, due to foundation flexibility. This can be of practical importance, particularly with heavily damped structures vibrating in the fundamental mode. With lightly damped structures, such as those assumed in Reference 1, this effect diminishes.
Seismic behaviour of above‐ground oil pipelines
Authors: Anderson James C. , Johnston Sterling B. 
Published: March 2007

AbstractThe dynamic behaviour of above‐ground oil pipelines which are allowed to slide back and forth on intermediate supports during strong motion earthquakes is studied. This sliding is resisted by friction between the pipe and the top of the support. The main objective of the study is to determine the effect of this non‐linear friction on both the static and dynamic stresses in the pipe. The study also considers the influence of other critical parameters such as: pipeline configuration, seismic wave velocity, initial temperature differential and internal pressure, and ground motion characteristics. Results show that the critical bending moments in the pipe occur during the static loading and that with seismic excitation, these moments tend to shake down as the pipe moves to a more stress free configuration. It is shown that the use of sliding friction can be an effective means of dissipating seismic energy and thereby damping the dynamic response of the pipeline even for low values of the coefficient of friction.
Induced torsional oscillations in symmetrical structures
Authors: Tso W. K. 
Published: March 2007

AbstractA study is made on the torsional‐lateral motions of non‐linear symmetrical structures subjected to lateral ground motion. The torsional and lateral response of a single mass symmetrical system subjected to sinusoidal ground motion is investigated. The load‐displacement relationship of the resisting elements is taken to be weakly nonlinear of a softening type. It is shown that non‐linear coupling exists between the lateral and rotational motions. For sinusoidal lateral response, the torsional motion equation can be cast in the form of a Mathieu equation. The likelihood of induced torsional response is then studied in terms of unstable regions in the parametric amplitude‐frequency parameter space. The implication of this type of non‐linear torsional‐lateral coupling to the responses of real symmetrical structures subjected to actual earthquake ground motion is then discussed.
Stability of columns subjected to earthquake support motion
Authors: Mostaghel Naser 
Published: March 2007

AbstractThe problem of stability of an initially straight, simple column which is subjected to dynamic overload due to the vertical component of ground acceleration during an earthquake is considered. The time history of this component of earthquake, its maximum absolute amplitude and a Liapunov's function are used to define a sufficient condition under which the column will always be stable. It is shown for the case of a simple column that this condition implies that the column will be stable as long as the maximum load which the column is subjected to is less than the Euler buckling load during an earthquake.
Dynamic response of a staggered wall‐beam structure
Authors: Mee A. L. , Jordaan I. J. , Ward M. A. 
Published: March 2007

AbstractA method for the dynamic analysis of staggered wall‐beam frames is developed using consistent mass terms which are derived and given in simple terms. The method uses effective stiffnesses for wall‐beam elements developed in an earlier paper. Experiments using a nine storey 1 : 15 scale perspex model are described. The first three natural frequencies of the model were obtained using two methods: sinusoidal external excitation of the structure with the base fixed and white noise excitation employing a single degree‐of‐freedom shake table, in the latter method with and without the addition of mass throughout the model. Agreement between analytical predictions of the first three natural frequencies and mode shapes and experimentally determined values is considered satisfactory, particularly for the first two modes. The lumped mass assumption gave reasonable results for these two cases, whereas the consistent mass theory gave reasonable results for the first three natural frequencies.
Non‐linear finite element dynamic analysis of axisymmetric solids
Authors: Nagarajan S. , Popov E. P. 
Published: March 2007

AbstractThe subject of this paper is the finite element analysis of axisymmetric solids subjected to axisymmetric static and dynamic loading, and taking into account material as well as geometric non‐linearities. A general Lagrangian formulation forms the basis for the incremental equations of motion which are solved using direct integration methods. Solution accuracy is improved by applying equilibrium correction loads at each step. Finite element discretization is achieved through the use of quadrilateral plane stress and axisymmetric elements with incompatible modes added for improvement of the element flexural characteristics. Several numerical examples are presented to demonstrate the effectiveness of the developed computer program.
Ground‐motion modelling at regional distances for earthquakes in a continental interior, I. Theory and observations
Authors: Herrmann Robert B. , Nuttli Otto W. 
Published: March 2007

AbstractTo understand the ground‐motion contribution by multiple‐mode surface‐wave arrivals, the surface‐wave theory required for predicting ground‐motion time histories is discussed. The adequacy of the theory in accounting for observed earthquake ground motion is tested by comparing theoretically predicted long‐period seismograms with real seismograms for two earthquakes in the central United States. The agreement between the predicted and observed maximum vertical component Lg ground velocities and accelerations in the 2‐ to 3‐sec period range is excellent over a distance range of 100 to 2,000 km.
Non‐linear models for simulating the dynamic damaging process of low‐rise reinforced concrete buildings during severe earthquakes
Authors: Takizawa Haruo 
Published: March 2007

AbstractThis paper is a study of idealizing a planar reinforced concrete frame as a non‐linear dynamic system for the purpose of simulating its inelastic behaviour during severe earthquakes. After having estimated the restoring force characteristics of all constituent members by experimental means (represented, for example, by a group of empirical equations), it is possible to estimate the non‐linear characteristics of the complete structure and to trace the damaging process for each constituent member under a given ground motion disturbance. However, this technique, which is directly based on member‐level properties, generally requires rather laborious computational procedures; for practical reasons it is necessary to develop a simplified model, reducing the required calculation without losing the substance of the mechanical phenomena. Thus the reliability of simplification by conventional shear modelling is examined in direct comparison with the response results from rigorous modelling. It is concluded that the shear modelling generally yields an inadequate and, in many cases, erroneous result. The primary cause leading to this discrepancy is identified and, based on this discussion, a more appropriate modelling as simple as conventional shear modelling is proposed.
Approximate natural frequencies for coupled shear walls
Authors: Rutenberg Avigdor 
Published: March 2007

AbstractAn approximate yet accurate formula is proposed for the natural frequencies of coupled shear walls under continuous medium assumptions. First the deflected shape of the structure is represented as the sum of two components: one due to flexural cantilever action and one due to shear‐flexure cantilever action. The natural frequencies of the latter two systems are then combined in Dunkerley's formula to yield the approximate frequency of the structure.
Blind signal reception in downlink time‐hopping ultrawideband communication system
Authors: Wu Wei‐Chiang 
Published: March 2007

AbstractUltra wideband (UWB) impulse radio (IR) system is currently being considered for several applications due to its attractive features that include low‐power carrierless modulation and ample multipath diversity. Among the various modulation and multiple‐access schemes, this paper deals with time‐hopping (TH) antipodal pulse amplitude modulation (PAM), operating in the presence of multipath‐fading downlink channel. We develop two types of low‐complexity mobile station (MS) receivers. One is based on the RAKE reception scheme and the other is designed to meet the minimum‐output‐energy (MOE) criterion. However, since accurate channel information is crucial for reliable operation, thereby we propose a blind (non‐data aided) channel estimator. Simulation results show that the MOE receiver outperforms the RAKE receiver in multiuser environment. Moreover, both the channel estimation algorithm and the MOE reception schemes are shown to be reliable and near‐far resistant. Copyright © 2007 John Wiley & Sons, Ltd.
Ship hydrodynamics computations with the CIP method based on adaptive Soroban grids
Authors: Takizawa Kenji , Tanizawa Katsuji , Yabe Takashi , Tezduyar Tayfun E. 
Published: March 2007

AbstractThe constrained interpolation profile/cubic interpolated pseudo‐particle (CIP) combined unified procedure (CCUP) method (J. Phys. Soc. Jpn. 1991; 60:2105–2108), which is based on the CIP method (J. Comput. Phys. 1985; 61:261–268; J. Comput. Phys. 1987; 70:355–372; Comput. Phys. Commun. 1991; 66:219–232; J. Comput. Phys. 2001; 169:556–593) and the adaptive Soroban grid technique (J. Comput. Phys. 2004; 194:55–77) were combined in (Comput. Mech. 2006; published online) for computation of 3D fluid–object and fluid–structure interactions in the presence of free surfaces and fluid–fluid interfaces. Although the grid system is unstructured, it still has a very simple data structure and this facilitates computational efficiency. Despite the unstructured and collocated features of the grid, the method maintains high‐order accuracy and computational robustness. Furthermore, the meshless feature of the combined technique brings freedom from mesh moving and distortion issues. In this paper, the combined technique is extended to ship hydrodynamics computations. We introduce a new way of computing the advective terms to increase the efficiency in that part of the computations. This is essential in ship hydrodynamics computations where the level of grid refinement needed near the ship surface and at the free surface results in very large grid sizes. The test cases presented are a test computation with a wave‐making wedge and simulation of the hydrodynamics of a container ship. Copyright © 2007 John Wiley & Sons, Ltd.
Efficient solution techniques for implicit finite element schemes with flux limiters
Authors: Möller M. 
Published: March 2007

AbstractThe algebraic flux correction (AFC) paradigm is equipped with efficient solution strategies for implicit time‐stepping schemes. It is shown that Newton‐like techniques can be applied to the nonlinear systems of equations resulting from the application of high‐resolution flux limiting schemes. To this end, the Jacobian matrix is approximated by means of first‐ or second‐order finite differences. The edge‐based formulation of AFC schemes can be exploited to devise an efficient assembly procedure for the Jacobian. Each matrix entry is constructed from a differential and an average contribution edge by edge. The perturbation of solution values affects the nodal correction factors at neighbouring vertices so that the stencil for each individual node needs to be extended. Two alternative strategies for constructing the corresponding sparsity pattern of the resulting Jacobian are proposed. For nonlinear governing equations, the contribution to the Newton matrix which is associated with the discrete transport operator is approximated by means of divided differences and assembled edge by edge. Numerical examples for both linear and nonlinear benchmark problems are presented to illustrate the superiority of Newton methods as compared to the standard defect correction approach. Copyright © 2007 John Wiley & Sons, Ltd.
Dynamics of Jovian atmospheres with applications of nonlinear singular vector method
Authors: Zhang Zhiyue , Lin Jing 
Published: March 2007

AbstractNonlinear singular vectors (NSVs) of a Jovian atmosphere model are obtained numerically in this paper. NSVs are the initial perturbation, whose nonlinear evolution attains the maximal value of the cost function, which is constructed according to the physical problem of interest. The results demonstrate that the motions of Jupiter's atmosphere is relatively stable under some assumptions. Copyright © 2007 John Wiley & Sons, Ltd.