摘要:

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.

ISSN:0098-8847    

DOI:10.1002/eqe.4290120102

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractWe present someerror expressionsfor 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 obtainingerror estimatesand, finally, we show some numerical results for a standard test problem which illustrate properties of the modal solutions.

ISSN:0098-8847    

DOI:10.1002/eqe.4290120103

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe effect of topography and subsurface inhomogeneity on surface motion is investigated in the case of Rayleigh waves. In the previous paper, the same effect was investigated in the case of SV waves. Several types of topography, such as cliffs both with and without a soft layer at the foot of the slope, are considered. Computations are made using a new hybrid method combining a particle model with a finite element method. In cases of harmonic Rayleigh waves, surface motions with amplitudes as large as 1.5 to 5 times the horizontal surface displacement of the incident Rayleigh waves are produced near the slope and the sloping interface. When a Rayleigh wave propagating through a hard single‐layered ground encounters a sloping interface where hard ground and soft ground make contact with each other, Rayleigh waves having two different, phase velocities are produced and they correspond to the fundamental mode, and the first mode determined by Haskell's method. In addition, the transient response when Rayleigh waves propagate through the cliff is also simulated. Assuming the vertical component of the Tokachi‐oki Earthquake (1968) measured on the surface to be a Rayleigh wave, the incident Rayleigh wave can be obtained by a Fourier synthesis of eigenfunctions of Rayleigh wa

ISSN:0098-8847    

DOI:10.1002/eqe.4290120104

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

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.

ISSN:0098-8847    

DOI:10.1002/eqe.4290120105

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe dynamic response of three‐dimensional rigid surface foundations of arbitrary shape is numerically obtained. The foundations are placed on a linear elastic, isotropic and homogeneous half‐space representing the soil medium and are subjected to either external dynamic forces or seismic waves of various kinds and directions, with a general transient time variation. The problem is formulated in the time domain by the boundary element method and the response is obtained by a time step‐by‐step integration. Two examples dealing with three‐dimensional rectangular foundations are presented in detail, together with comparisons with other methods, in order to document the accuracy of the method. The main advantages of the proposed method are that, unlike frequency domain techniques, it provides directly the transient response and forms the basis for extension to the case of non‐linea

ISSN:0098-8847    

DOI:10.1002/eqe.4290120106

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractThe paper deals with the influence of the epicentral direction on the displacement and stress response of multistorey asymmetric buildings to earthquake horizontal ground motion.A method is given for computing for each plane frame of the complex structure a particular direction of the bidirectional stationary random input for which the horizontal floor displacement of the given frame is maximized. It is shown that this direction can be considered conservative for the corresponding non‐stationary proces

ISSN:0098-8847    

DOI:10.1002/eqe.4290120107

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

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

ISSN:0098-8847    

DOI:10.1002/eqe.4290120108

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

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 dampi

ISSN:0098-8847    

DOI:10.1002/eqe.4290120109

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

摘要:

AbstractAn exact numerical time integration of scalar equations for undamped structural systems is presented. Typical numerical examples are included to illustrate the use of the proposed procedure.

ISSN:0098-8847    

DOI:10.1002/eqe.4290120110

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290120111

出版商:John Wiley&Sons, Ltd    

年代:1984

数据来源: WILEY