bluuebunny/crossref_metadata_2025_split huggingface dataset:
Site‐dependent critical design spectra
Authors: Wang P. C. , Yun C. B. 
Published: March 2007

AbstractA new type of seismic response spectrum is presented. It is based on the concept of a ‘ critical excitation’ which is defined here as an excitation among a certain class of excitations that will produce the largest response peak for a design variable of interest. Site conditions, namely rock, stiff soil and deep cohesionless soil, are taken into account through the definition of the class of allowable excitations. The response spectra thus produced are compared with others that have been proposed or used in the past. Results indicate that they lead to realistic if somewhat conservative assessment of structural earthquake resistance. On the other hand, they are derived under assumptions that are rather well supported by seismological observation and avoid other questionable assumptions, especially those regarding the statistics of ground motions. The critical response spectra may thus inspire greater confidence on the part of their users than those currently proposed or relied on.
A decision‐theory methodology for the selection of buildings for strong‐motion instrumentation
Authors: Hart G. C. , Rojahn C. 
Published: March 2007

AbstractCurrent projections indicate that six buildings per year will continue to be instrumented under the California Strong‐Motion Instrumentation Program for the next several decades. In order to select these buildings systematically for instrumentation, we have developed a methodology that incorporates the fundamental elements of decision theory. These elements include an identification of the types of buildings that should be instrumented, a definition of the expected severity of ground shaking at each possible building site along with the probability of occurrence, and a quantification of the relative value of obtaining a building‐response record for each building type. Using this information, we can apply decision theory to calculate the expected utility (degree of preference) of instrumenting buildings of a particular type at various sites. The sites are then ranked in order of preference for each building type. This procedure, developed for the California Strong‐Motion Instrumentation Program, can be extended to instrumentation programs in other areas.
Dynamic behaviour of a cable‐stayed bridge
Authors: Fleming John F. , Egeseli Engin A. 
Published: March 2007

AbstractThe dynamic response of a cable‐stayed bridge to seismic, wind and simulated traffic loads is discussed. The analysis procedure which is used considers non‐linear behaviour of the cables, caused by the variation in sag with tensile force, and non‐linear behaviour of the bending members, caused by the interaction of axial and bending deformations. It is concluded that the non‐linearity of the structure must be considered in determining the stiffness of the structure in the dead load deformed state. A linear dynamic analysis, however, starting from the dead load deformed state will give results within normally required design accuracy.
Seismic design response by an alternative SRSS rule
Authors: Singh Mahendra P. , Mehta K. B. 
Published: March 2007

AbstractThe square root of the sum of the squares (SRSS) procedure and its modified forms are often used to obtain seismic design response. The design inputs for such procedures are usually defined in terms of pseudo velocity or acceleration response spectra. Erroneous results have been obtained with these existing SRSS procedures, especially in the calculation of responses where high frequency effects dominate. Here an alternative SRSS procedure is developed using the so‐called mode acceleration approach of structural dynamics. The design input in this procedure is defined in terms of relative acceleration and relative velocity spectra. The relative spectra can be related to pseudo spectra. For a given number of modes to be included in the analysis the new SRSS rule proposed here will reduce the error due to the so‐called ‘missing mass’ effect and predict a more accurate response value than the rules which use pseudo spectra as input, for systems either with or without dominant high frequency mode effects.
Intensity of waves in a randomly non‐homogeneous layered medium
Authors: Hryniewicz Z. 
Published: March 2007

AbstractThe intensity of shear waves in the model of a multilayered stratum, the material properties of which are random functions, is considered. The solutions for displacements and stresses are obtained for one layer and then the formulation is extended to a multilayered stratum through transfer matrices. The solution for a random medium has been compared with the solution for the homogeneous medium. The analysis indicates that the stochastic inhomogeneities are likely to increase the damping in a significant way.
Some error bounds and numerical experiments in modal methods for dynamics of systems
Authors: Gladwell I. , Hanson P. M. 
Published: March 2007

AbstractWe present some error expressions for approximate modal solutions of viscously damped linear structural vibration equations; these approximations are calculated by a variety of modal techniques. Motivated by our numerical experience, we show the equivalence of some different modal solutions in the presence of classical damping and, in passing, we obtain a previously unremarked manifestation of this type of damping. We make some brief comments about obtaining error estimates and, finally, we show some numerical results for a standard test problem which illustrate properties of the modal solutions.
Dynamic response of pipelines to moving loads
Authors: Datta S. K. , Chakraborty T. , Shah A. H. 
Published: March 2007

AbstractVibration of buried pipelines induced by moving axial and radial loads has been studied in this paper. A thin shell model has been used for the pipeline, which is assumed to be lying in an infinite isotropic homogeneous elastic medium. In order to allow for the possible motion of the pipe out of phase with the surrounding ground a very thin layer of viscoelastic material is assumed to separate the pipe from the ground. Calculations indicate the presence of the interfacial viscoelastic layer does not influence the pipe response in a significant manner. So all the numerical results presented here are for the case when the pipe is assumed to be perfectly bonded. These show that the maximum pipewall displacements and stresses occur in a soft soil at long wavelengths.
On the effective seismic input for non‐linear soil‐structure interaction systems
Authors: Bielak Jacobo , Christiano Paul 
Published: March 2007

AbstractTwo equivalent semi‐discrete formulations are presented for the problem of the transient response of soil‐structure interaction systems to seismic excitation, considering linear behaviour of the soil material and arbitrary non‐linear structural properties. One formulation results in a direct method of analysis in which the motion in the structure and the entire soil medium, rendered finite by an artificial absorbing boundary, is determined simultaneously. The other represents a substructuring technique in which the structure and the soil are analysed separately.The forces induced in the discretized system by the incident seismic motion are obtained as part of the general formulation by using the free‐field motion of the unaltered soil as the earthquake input. It is shown that these forces act within the soil region in the direct method, but only on the soil‐structure interface in the substructure formulation. Both sets of forces, however, involve only the displacements and tractions acting on the fictitious surface in the unaltered (linear) soil which coincides with the soil‐structure interface of the complete system. It is shown, further, that the free‐field displacements alone define a minimal set of data for evaluating the seismic response of the structure, since the tractions and displacements on that surface are interrelated. In practice, the minimal set must be obtained by extrapolating the available information, as the free‐field ground motion at a site is usually specified at a single reference point.
Modal decomposition method for stationary response of non‐classically damped systems
Authors: Igusa Takeru , Kiureghian Armen Der , Sackman Jerome L. 
Published: March 2007

AbstractThe stationary response of multi‐degree‐of‐freedom non‐classically damped linear systems subjected to stationary input excitation is studied. A modal decomposition procedure based on the complex eigenvectors and eigenvalues of the system is used to derive general expressions for the spectral moments of response. These expressions are in terms of cross‐modal spectral moments and explicitly account for the correlation between modal responses; thus, they are applicable to structures characterized with significant non‐classical damping as well as structures with closely spaced frequencies. Closed form solutions are presented for the important case of response to white‐noise input. Various quantities of response of general engineering interest can be obtained in terms of these spectral moments. These include mean zero‐crossing rate and mean, variance and distribution of peak response over a specified duration. Examples point out several instances where non‐classical damping effects become significant and illustrate the marked improvement of the results of this study over conventional analysis based on classical damping approximations.
Hazardous buildings: Aspects of the los angeles earthquake problem
Authors: Lee D. M. , Shepherd R. 
Published: March 2007

AbstractIn recognition of the life‐threatening dangers posed by many thousands of buildings completed prior to the requirement for provision of any specific earthquake resistance, in 1981 the City of Los Angeles adopted a seismic safety ordinance requiring the upgrading of these buildings to predetermined engineering standards. Various methods of modifying such structures, which are characteristically of unreinforced multi‐storey masonry bearing wall configuration with interior wood framing, are summarized in this paper. In addition to presenting typical structural details, some of the socio‐economic and financial aspects of the earthquake hazard mitigation programme are discussed.
Transient flexural vibrations of a timoshenko column supported by an elastic half‐space
Authors: Wada H. 
Published: March 2007

AbstractTransient flexural vibrations of an elastic column supported by an elastic half‐space are investigated analytically under the condition that an arbitrarily shaped free‐field lateral acceleration is given as an input. Applying the Timoshenko theory to the column and making use of Laplace transformations with respect to time and numerical inverse Laplace transformations, the time histories of the column free end acceleration are presented. Numerical results obtained from the Timoshenko theory are compared with those of a previous paper1 (applying the Bernoulli‐Euler theory to the column), and the effects of column slenderness and foundation stiffness on the transient flexural vibrations of the column are clarified.
Dynamic response of twin circular tunnels due to incident SH‐waves
Authors: Balendra Thambirajah , Thambiratnam David P. , Koh Chan Ghee , Lee Seng‐Lip 
Published: March 2007

AbstractThe steady‐state solution for two parallel under ground tunnels of circular cross‐section subjected to incident plane harmonic SH‐waves is obtained in closed form, by using the method of wave function expansion. The image technique is employed to account for the reflection of waves at the ground surface. Numerical studies are carried out to determine the influence of spacing between the tunnels on the shear stresses in concrete and steel linings.
The optimum design of a base isolation system with frictional elements
Authors: Constantinou Michalakis C. , Tadjbakhsh Iradj G. 
Published: March 2007

AbstractA linear multistorey structure with a seismic base isolation system consisting of rubber bearings and frictional elements is considered. The non‐linear equations of motion are derived for the first mode vibration and the stochastic response to a white noise ground acceleration is determined. Based on this response, suitable objective functions are defined and the optimum design of the isolation system is performed. It is shown that a small amount offriction increases the effectiveness of the system compared with the same system but without frictional elements.
Soil‐structure interaction effects on the steady‐state response of torsionally coupled buildings
Authors: Tsicnias T. G. , Hutchinson G. L. 
Published: March 2007

AbstractThe work presented in this paper investigates the effect of the foundation flexibility on the coupled lateral‐torsional response of single‐storey buildings excited by translational ground motion. The eccentricity between the centre of mass and the centre of resistance is considered to be the only cause of coupling of the lateral and torsional response of the building.The study is confined to the steady‐state response of rigidly supported and flexibly supported torsionally coupled buildings subjected to harmonic free‐field ground displacement perpendicular to the direction of the eccentricity. In the case of the flexibly supported building the foundation medium is assumed to be an elastic homogeneous isotropic half‐space.The effect of the controlling parameters on lateral‐torsional coupling is investigated. It is concluded that for a particular range of values of these parameters (representing most cases of actual buildings) their effect on the coupling of lateral and torsional response is not qualitatively affected by increases in the flexibility of the foundation medium.
Finite element versus simplified methods in the seismic analysis of underground structures
Authors: Gómez‐massó Alberto , Attalla Ibrahim 
Published: March 2007

AbstractSeismic analysis of buried tunnels is considered herein. A comparison of results is carried out between a detailed finite element analysis and several simplified models for hand calculation. The finite element analysis is conducted by superimposing the free field motions and the interaction motions. The latter are calculated in a plane strain geometry taking into account the influence of adjacent structures with an approximation for 3‐D effects and for soil non‐linearities. Simplified models give, in general, conservative results, although better approximations are obtained by modelling the tunnel bends, where stress concentration occurs.
Evaluation of deformation of tunnel structure due to Izu‐Oshima‐Kinkai earthquake of 1978
Authors: Kawakami Hideji 
Published: March 2007

AbstractDue to the Izu‐Oshima‐Kinkai earthquake of 1978, the Inatori tunnel, a single‐track railway tunnel in Japan, was severely damaged. This damage was mainly caused by the main fault and a subsidiary fault which is estimated to have traversed the tunnel. The objective of this paper is to evaluate the performance of available mathematical models of earthquake wave propagation by taking advantage of the actual damage data of this tunnel. This paper has also the purpose of contributing to the earthquake‐resistant design procedure of the tunnel in the source region by estimating its deformation using the fault mechanical model. In this paper using a set of fault parameters previously proposed by seismologists for the Izu‐Oshima‐Kinkai earthquake, the longitudinal, transverse and vertical displacements of the tunnel axis are computed. These computed results are then compared with the surveyed residual deformation. For each of three deformation components a similar trend can be recognized, and the comparison indicates that a reasonably good correlation exists between these surveyed and computed displacements.
Dynamic‐stiffness matrix of soil by the boundary‐element method: Embedded foundation
Authors: Wolf John P. , Darbre Georges R. 
Published: March 2007

AbstractGreen's influence functions are derived for a linearly distributed load acting on part of a layered elastic halfplane on a line which is inclined to the horizontal. Using these Green's functions as fundamental solutions in the boundary‐element method, the dynamic‐stiffness matrices of the unbounded soil with excavation, of the excavated part and of the free field are calculated. The indirect boundary‐element method using distributed loads and no offset leads to more accurate results than the weighted‐residual technique and the direct boundary‐element method. At the natural frequencies of the undamped excavated part built‐in along the structure‐soil interface, the spring coefficients associated with the dynamic‐stiffness matrices of the excavated part and of the free field will become infinite. If the dynamic‐stiffness matrix of the soil with excavation is calculated as the difference of that of the free field and that of the excavated part, the difference of two large numbers will arise in the vicinity of these frequencies. A consistent discretization must then be used. In particular, the dynamic‐stiffness matrix of the embedded part cannot be determined by the finite‐element method in this case. A parametric study is performed for the dynamic‐stiffness matrix of the free field for a rectangular foundation embedded in a halfplane and in a layer built‐in at its base; the aspect ratio and the damping of the soil are varied.
Dynamic phenomena in ropeways after a haul rope rupture
Authors: Portier B. 
Published: March 2007

AbstractThe aim of the work presented here is to provide an accurate prediction of the dynamical behaviour of reversible aerial ropeways. A mechanical and numerical model is developed in order to check the safety of any such ropeway after a haul rope rupture.The whole installation (including carriers, counterweights and ropes) is first given an initial position. The model then simulates the disappearance of some cables and counterweights, and evaluates the subsequent displacements of the remaining parts, excluding track ropes. The model uses very simple first‐order finite elements, accounting for non‐linear effects caused by large displacements. The numerical integration is very efficient, and suits the capabilities of small microcomputers; it does not require matrix inversions, nor stiffness matrix evaluations.A full‐scale experiment has recently been carried out on a ropeway in the French Alps. If a simple kind of viscous damping is accounted for, numerical and experimental results compare with a reasonable accuracy. The present model is now in use for design and control of actual ropeway equipment.
Vibrations of beams with an absorber consisting of a viscoelastic solid and a beam
Authors: Yamaguchi H. , Saito H. 
Published: March 2007

AbstractThis paper considers the response of a beam with a dynamic vibration absorber, which consists of a viscoelastic solid and a double‐cantilever viscoelastic beam, attached to the centre of the main beam. The ends of the main beam are built in and excited sinusoidally by the base motion. The transfer matrix method is used in the analysis. The displacement transmissibility, i.e. the ratio of the displacement at the centre of the main beam to that of the base is investigated in the numerical example. It is shown that the present absorber is effective to suppress several resonances of the main beam simultaneously by only one compact device. Values of the optimum tuning design parameters are presented in the numerical example.
Some methods for the analysis of equipment‐structure interaction
Authors: Ingham Tim J. , Sackman Jerome L. 
Published: March 2007

AbstractWe present some numerical methods which simplify the analysis of equipment‐structure systems composed of an equipment component which is light with respect to the structure component. We consider completely general forms of equipment‐structure interaction. In particular, we consider that an arbitrary number of natural frequencies of the equipment and the structure are nearly equal (or equal) to each other.We show that this coincidence of natural frequencies implies that the equipment‐structure system will itself have several closely spaced natural frequencies. The essence of equipment‐structure interaction is the formation of beats, with slowly varying amplitude in each degree of freedom, between these natural frequencies‐at least in response to a δ‐function ground motion.We derive some differential equations, the solutions of which are a slowly varying envelope function (a vector) which yields the above slowly varying amplitudes. It is obtained by numerical integration using some conventional, but modified, methods and using a step size appropriate to capture its slowly varying nature.This envelope function defines the response to a δ‐function ground motion. We show how it may be combined with the properties of an arbitrary ground motion (acceleration record or response spectrum) to yield the response to such a ground motion.
Reliability of structures subjected to differential fault slip
Authors: Kiremidjian Anne S. 
Published: March 2007

AbstractThis paper presents a method for determining the probabilities of fault displacement at specific locations on a fault of finite length. The method is further extended to include a procedure for estimating the maximum strain, stress and axial tensile force in a pipe crossing a fault. With this procedure, estimates are also obtained for the curved lengths of the pipe. The feasibility of the method is demonstrated through a specific example. For that purpose an X‐60 pipe crossing the San Andreas fault in Northern California is used. The procedure is particularly useful in risk consistent design and can be readily extended to structures other than underground pipes.
Free vibration of asymmetric shear wall‐frame buildings
Authors: Balendra Thambirajah , Swaddiwudhipong Somsak , Quek Ser‐Tong , Lee Seng‐Lip 
Published: March 2007

AbstractThe Galerkin method of weighted residuals is used to determine the frequencies and associated mode shapes of asymmetric shear wall‐frame structures. The governing equations are formulated using the continuum approach by idealizing the structure as a shear‐flexure beam. Varying properties along the height of the building are considered. The effect of translational, rocking and torsional flexibilities of the foundation on the natural frequencies is also investigated. The method presented herein utilizes polynomial and transcendental displacement functions, and is found to be simple, versatile and efficient.
Earthquake analysis of concrete gravity dams including reservoir bottom absorption and dam‐water‐foundation rock interaction
Authors: Fenves Gregory , Chopra Anil K. 
Published: March 2007

AbstractThe available substructure method for the earthquake analysis of concrete gravity dams, including the dynamic effects of the impounded water and the flexible foundation rock, is extended to include the effects of alluvium and sediments invariably present at the bottom of actual reservoirs. Modelled approximately by a reservoir bottom that partially absorbs incident hydrodynamic pressure waves, these effects are incorporated into the continuum solution for the hydrodynamic pressure. The dam‐water‐foundation rock system is idealized as a two‐dimensional system and analysed under the assumption of linear behaviour.An example earthquake analysis is presented to demonstrate the results obtained from the analytical procedure. Computation times for several cases illustrate the efficiency of the analytical procedure. In particular, the additional computation time required to include reservoir bottom absorption is shown to be very small.