摘要:

AbstractThe error‐propagation characteristics of an implicit time integration algorithm in pseudodynamic testing are examined. It is shown that the implicit algorithm is superior to explicit integration algorithms in terms of experimental error amplification. The influence of systematic experimental errors is studied and methods for controlling these errors are examined. In spite of the fact that the implicit algorithm is unconditionally stable, it is shown that the integration time interval in a pseudodynamic test is limited by the calibration range of the electronic hardware as well as the degree of participation of the higher modes. Furthermore, the tolerance for experimental errors decreases as the integration time interval increase

ISSN:0098-8847    

DOI:10.1002/eqe.4290190502

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper considers a solution method for viscously damped linear structural systems which are subjected to transient loading. The equations of motion of such systems are written in a first‐order form. A solution subspace is generated using the damped dynamic matrix and the static deflection from the first‐order form of the equations of motion. Two convenient bases, Lanczos vectors and Ritz vectors, are constructed from this subspace. An approximate solution is then obtained by superposition of the Lanczos vectors or the Ritz vectors. In contrast to the traditional mode superposition method using complex eigenvectors, the Lanczos vectors or the Ritz vectors are less expensive to generate than the complex eigenvectors, yet yield comparable accuracy. In addition, there is no need for a static correction since the static deflection is already contained in our solution subspace. Numerical examples are presented to show the potential of using the Ritz vectors to compute responses of damped dynamic syst

ISSN:0098-8847    

DOI:10.1002/eqe.4290190503

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSteady state scattering of incident P, SV, SH and Rayleigh waves by general non‐axisymmetric three dimensional dipping layers is investigated by using an indirect boundary integral equation method. Material of the half‐space and the layer is assumed to be linear, weakly anelastic, homogeneous and isotropic.Systematic comparisons between three dimensional and two dimensional models demonstrate that the validity of a two dimensional approximation for a given basin shape may be affected strongly by changes in azimuthal angle of incidence, type of incident wave and frequency. The discrepancies of two dimensional modelling appear to be much more pronounced for the case of an incident SH wave. Another important feature of the results is the existence of strong coupling between P/SV and SH modes, which has no correspondence in two dimensional models. Such off‐azimuthal mode conversions are particularly strong for an incident SH

ISSN:0098-8847    

DOI:10.1002/eqe.4290190504

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractTransient response of three dimensional dipping layers of different shapes subjected to incident P, SV, SH and Rayleigh waves is investigated. The time domain response is constructed from steady state solutions through the Fourier synthesis. An indirect boundary integral equation method is applied to calculate the required steady state solutions. The material of the half‐space and the layer is assumed to be linear, weakly inelastic, homogeneous and isotropic.Numerical results show that the maximum amplification of motion is strongly dependent upon the type of incident wave, the shape of the basin and signal frequency. The change in the shape of the valley from hemispherical to semi‐prolate causes a significant increase in the amplitude of surface waves near the edges; however, the maximum amplification of motion near the centre of the valley decreases. This phenomenon is especially apparent for the case of an incident P wave. In comparison to the corresponding two dimensional responses, the amplitude of motion near the centre of the valley is in general higher for three dimensional mod

ISSN:0098-8847    

DOI:10.1002/eqe.4290190505

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractWe propose an effective and reliable time‐domain substructure technique which takes soil‐structure interaction effects into account and uses the flexibility coefficients of unbounded soil obtained in the frequency domain. Compared with previous methods, the frequency points to calculate flexibility coefficients, and computational loads in the calculation of time‐domain interaction forces, are reduced.In the formulation, we have assumed the flexibility coefficient to be a periodic function, obtained within the bandlimited frequency range, which also includes the predominant frequencies of the structure and incident wave. Then we simulate the periodic flexibility coefficients using discrete impulse responses in the time‐domain analyses. However, the real and imaginary parts of the bandlimited flexibility coefficients do not form a Hilbert transform pair; the discrete impulse responses should be modified to be causal for the time‐domain analyses. We present various discrete impulse responses which have been obtained from only the real part, only the imaginary part and from both the real and imaginary parts of the frequency‐domain flexibility coefficients by FFT with causality conditions. Through a numerical example the relationship between the modified discrete impulse responses and the validity of the time‐domain substructure method

ISSN:0098-8847    

DOI:10.1002/eqe.4290190506

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractNon‐linear seismic soil‐structure interaction is studied through a hybrid procedure using the pseudo‐dynamic testing (PDT) method which is modified to take into account frequency dependence and developed for foundation‐soil systems. The numerical scheme used in conventional PDT is improved by introduction of a time‐dependent pseudo‐forcing function which is derived from frequency‐dependent dynamic characteristics of the system by means of Hilbert transformation in the frequency domain. Surface, shallow and caisson foundation models that differed in size and depth of embedment were used. The mechanical characteristics of the systems were determined from static and forced vibration dynamic tests. An amplitude scaling technique was used for three recorded

ISSN:0098-8847    

DOI:10.1002/eqe.4290190507

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe seismic analysis of a reactor building on a sliding‐type base isolation is performed by way of the hybrid frequency‐time‐domain procedure. The frequency dependence of the foundation stiffness coefficients is duly accounted for in the analysis, although the problem is non‐linear. The response results are shown to be reliable by way of comparison with the results of a time‐stepping algorithm in the specialized case of constant foundation stiffness coefficients. The fact that such an analysis can be performed is an outstanding result, particularly when considering that no difficulties are encountered in the implementation and in the calculation. The flow chart used to implement the procedure is presented in the paper.The reactor building is analysed for three different sites with each site having three sets of material properties. It appears that the structural response is not strongly affected by the frequency dependence of the foundation stiffness coefficients. This also holds true as far as the response of equipment attached to the superstructure is concerned. For all practical purposes this frequency dependence may be disregarded in favour of constant spring and damping coe

ISSN:0098-8847    

DOI:10.1002/eqe.4290190508

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe response of multi‐degree‐of‐freedom (MDOF) structures with sliding supports is studied. The problem of sliding structures is a discontinuous one in that different numbers of equations of motion with varying forcing functions are required for the sliding and non‐sliding phases. The numerical difficulties involved in this regard in an incremental finite element analysis can be circumvented through the introduction of a fictitious spring for the sliding support. Such a treatment enables one to study the higher mode effects on MDOF sliding structures under the excitation of harmonic or earthquake motions. The dynamic characteristics of MDOF sliding structures will be highlighted in the analysis of a four‐storey shear building with slidin

ISSN:0098-8847    

DOI:10.1002/eqe.4290190509

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe inelastic response of a single‐degree‐of‐freedom (SDOF) system to different sets of earthquake records was analysed to study the significance of ground motion characteristics on structural damage. Six non‐linear models were used. The ductility ratio and hysteretic energy index were chosen as two important damage indices to measure the structural damage. The dispersion phenomenon exhibited by yield spectra due to input ground motion was reduced by incorporating the ground motion a/v ratio into the two damage indices. Finally, empirical formulae for estimating two measures of structural damage were developed for each hystereti

ISSN:0098-8847    

DOI:10.1002/eqe.4290190510

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290190511

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY