摘要:

AbstractA study of the dynamic impedances of horizontally excited, radially inhomogeneous, infinite viscoelastic soil layers with a circular hole, and of piles embedded in a medium represented by such layers is made considering the shear modulus of the material to increase radially within a narrow annular boundary zone. Unlike a previous study in which the boundary zone was presumed to be massless, in the present study the inertia effects of this zone are taken into account. The impedances are evaluated over wide ranges of the parameters involved and the sensitivity of the results is assessed. The results are also compared with those obtained for similarly excited homogeneous layers and for vertically excited inhomogeneous layers. For purposes of analysis, the inhomogeneous boundary zone is represented by a series of concentric rings of constant properties, and the transfer matrix technique is used to evaluate the results. The analysis and the computer program used to implement it are applicable to layers of arbitrary radial variation of material properties.

ISSN:0098-8847    

DOI:10.1002/eqe.4290160702

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn engineering seismic hazard probabilistic analysis, physical constraints are generally overlooked. We formulate such constraints for the general case of a site within an annular seismogenic zone. This configuration provides a first approximation of seismic hazard analysis within a broad zone undergoing crustal deformation; such zones are a common expression of continental tectonics. Applications are restricted to medium size earthquakes (Ms<7). The formulation is applied to two cases reflecting the mid‐plate (case I) and plate boundary (case II) seismotectonic environments. It is found that, for a given strain rate and for an upper bound magnitude of 6 3/4, the extreme hazard in both the environments is the same but of different character. In the plate boundary example, it is associated with widespread ground deformation while in the mid‐plate example, it involves more intense ground motion. On the other hand, if the upper bound magnitude is 5 3/4, the extreme hazard is likely to be an order of magnitude less in case I than in case II. Moreover, when the extreme hazard is associated with singular conditions generated by a single fault, the assumption of a Poissonian process may not be safe for earthquake resistant design decisi

ISSN:0098-8847    

DOI:10.1002/eqe.4290160703

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe paper brings up to date and amplifies earlier work on earthquake‐induced ground displacements using near‐field strong‐motion records, improved processing procedures and a homogenizing treatment of the seismological parameters. A review of upper bound limits to seismic displacements is given and a predictive procedure is examined that allows the probabilistic assessment of the likelihood of exceedance of predicted displacements to be made in the near field of earthquakes in the magnitude range 6.6 to 7.3. Using a considerable number of unscaled ground motions obtained at source distances of less than half of the source dimensions, graphs and formulae are derived that allow the assessment of permanent displacements of foundations and slopes as a function of the critical acceleration

ISSN:0098-8847    

DOI:10.1002/eqe.4290160704

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA method to combine probabilistic seismic hazard analysis and stochastic earthquake motion models is presented. A set of parameters characterizing stochastic earthquake motion models is determined on a consistent probabilistic basis. The method proposed herein consists of two steps. First, the ground motion intensity is determined in the context of the conventional hazard curve technique. Next, other ground motion parameters such as duration, predominant frequency and spectral shape parameters are determined as conditional means corresponding to the annual probability of exceedance for the ground motion intensity. Some example applications are presented.

ISSN:0098-8847    

DOI:10.1002/eqe.4290160705

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMeasured accelerations and water pressures obtained during a recent forced vibration test on a large thin arch dam at high water are compared to predictions from a finite element model for which water compressibility is both included and neglected. The numerical model is calibrated using the antisymmetric response data because they are only slightly affected by water compressibility; good agreement is obtained. In the effort to reproduce the symmetric response data, for which water compressibility plays a strong role, the calibrated model shows better correlation when water compressibility is included, but the agreement is still inadequate. A successful isolation of the fundamental water resonance from the experimental data shows significantly different features from those of the numerical water model, indicating possible inaccuracy in the assumed geometry and/or boundary conditions for the reservoir. Some other results at low water level are also included.

ISSN:0098-8847    

DOI:10.1002/eqe.4290160706

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractAn advanced application of BEM to the problem of wave screening by barriers is described. The BEM formulation has been developed by utilizing advanced surface modelling, automatic (self‐adaptive) error control in the numerical integration. The soil is modelled as a layered, isotropic and linear elastic or viscoelastic medium. The results of the analysis have been compared with full scale test dat

ISSN:0098-8847    

DOI:10.1002/eqe.4290160707

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThis paper investigates the peak response of a 2‐DOF uncoupled linear oscillator under arbitrarily oriented two‐component horizontal earthquake motion. Input data consist of 22 two‐component acceleration records from the magnitude 6.6, October 15, 1979 Imperial Valley earthquake. One‐directional response spectra for each principal direction of the oscillator, and two‐directional response spectra (amplitude of the peak resultant response and its direction with respect to principal directions) are calculated by considering all angles of incidence of the excitation. The results indicate that, for oscillators that are not too flexible (i.e. with natural frequencies greater than 0.8 Hz), the two‐directional peak response is controlled by the weaker direction of the oscillator. For flexible oscillators the two‐directional peak response is controlled by the direction whose natural frequency is closer to dominant ground motion frequencies. The results also show that when the two‐directional peak response is expressed as a weighted sum of one‐directional peak responses, the weighting factors are not constants, but functions of oscillator and dominant ground m

ISSN:0098-8847    

DOI:10.1002/eqe.4290160708

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractLocal uplift of the tank wall is perhaps the most important characteristic of the seismic behaviour of unanchored liquid storage tanks made out of steel. Such uplift is necessary, because unanchored tanks rely primarily on the weight of the liquid resting on an uplifted portion of the base plate to balance the overturning moments that occur during strong shaking. A simplified method of analysis for static lateral loads is developed, based on the assumption that the restraining action of the base plate can be modelled with equivalent, non‐linear springs. This assumption, together with a Fourier decomposition of the displacements, simplifies the problem to the extent that it can be solved on a personal computer. The solutions are compared with those from experiments and those from current U.S. design analysis method

ISSN:0098-8847    

DOI:10.1002/eqe.4290160709

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMany liquid storage tanks consist of a steel cylindrical shell, which is welded to a base plate, but not fixed to the foundation. When such an unanchored tank is subjected to lateral loads due to earthquake induced hydrodynamic pressures in the liquid, the tank wall tends to uplift locally, pulling the base plate up with it. The contact problem of the partially uplifted base plate and its interaction with the the cylindrical shell is solved in this paper using the finite difference energy method, and a Fourier decomposition of the displacements in the circumferential direction. Non‐linearities due to contact, finite displacements and yield of the steel are included in the analysis. However, the equations for the shell are linearized. This uncouples the equations for the Fourier displacement coefficients in the cylindrical shell, and enables the degrees of freedom for the shell to be eliminated by static condensation at very little computational cost.Comparing the analytical results to (for the most part existing) experimental results, produces good agreement in some cases and not so good in others. A number of effects that could give rise to such differences are discussed. In most cases they represent experimental conditions that are not known or modelled in the analysis. The analysis results are also compared to those from a simplified analysis in which the hold‐down action of the base plate is modelled by means of nonlinear Winkler spri

ISSN:0098-8847    

DOI:10.1002/eqe.4290160710

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290160712

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY