摘要:

AbstractAn analytical model is developed to evaluate performance characteristics of unidirectional seismic simulators (shaking tables). The validity of the model is verified with experimental measurements of the frequency response of the shaking table at the Catholic University of Peru.Interaction effects between shaking table and structure are first studied by analysing the response of a two DOF (degree of freedom) oscillator with mechanical properties representative of the actuator‐table‐structure system. A single DOF viscoelastic oscillator representing the structural test specimen is then included in the analytical model of the seismic simulator, and the behaviour of the combined system is evaluated, in the frequency domain, in terms of response stability and accuracy of reproduction of the command signal. Numerical simulations of system response under different load conditions are subsequently performed in order to study the influence of shaking table and test structure characteristics on the interaction phenomenon.The results obtained explain some of the performance degradation observed in seismic simulation tests involving very heavy structures and provide guidelines for the design of more reliable shaking table syst

ISSN:0098-8847    

DOI:10.1002/eqe.4290160402

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA dynamic analysis technique is presented that can be used to determine the response of a discrete model of a large linear structural system composed of multiple substructures. The technique circumvents the costly computation of the modal characteristics of the combined system. This is accomplished by relying on a predictor‐corrector scheme to converge iteratively to the interface accelerations of the combined system, while the equations of motions of the individual structures are integrated separately. In this regard, the temporal slopes of the interface accelerations (jerks) are computed at each time point of integration to predict the interface accelerations at the next time point. The proposed technique is exemplified by conducting a space shuttle landing loads analysis; the obtained numerical data demonstrate its reliability and efficienc

ISSN:0098-8847    

DOI:10.1002/eqe.4290160403

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe behaviour of a building subjected to a strong‐motion earthquake depends highly on its energy dissipation capacity. By introducing three‐stage friction‐grip elements, the energy dissipation within each storey can be ‘designed’ according to definable stages (e.g. serviceability, medium‐ and strong‐motion earthquake). Tests on simple steel‐concrete‐ and steel‐steel‐friction‐grip connections have proved their very satisfactory behaviour under high dynamic loading, showing no considerable damage when well designed. Examples of horizontal stiffening elements are given to illustrate the construction of three‐stage elements with either steel‐steel‐ or steel‐concrete‐friction‐grip joints.By computing the response of a seven storey building designed as a steel frame (‘ductile system’ philosophy), concrete core (‘stiff system’‐philosophy) and three‐stage truss and being subjected to the 1940 El Centre earthquake, the superior performance of three‐stage elements and its economic advantage over the other two systems becomes apparent. Although this is just one illustrative example, it is nevertheless an important one, because it resembles the type of building that would respond best to the application of three‐stage building brakes. Finally, the result of an online test on a three‐stage element is given. This realistic earthquake simulation proved the behaviour to be adequately close to the basic philosophy and yielded i

ISSN:0098-8847    

DOI:10.1002/eqe.4290160404

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTransient pressures generated by earthquake shaking in hydrotechnical tunnels are evaluated by the discrete Fourier transform technique. The effects of the horizontal ground motion accelerating the closed downstream tunnel gate, as well as the upstream dam face, and the influence of the vertical motion of the reservoir floor are considered in this analysis. An example of a typical bottom outlet is analysed by subjecting it to several computed accelerograms. It is shown that high hydrodynamic pressures can be developed, several times larger than the hydrostatic pressure.

ISSN:0098-8847    

DOI:10.1002/eqe.4290160405

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe problem of damping the vibration amplitude of machines and structures has considerable practical importance. This paper discusses the design of optimum vibration absorbers for linear damped systems operating at a certain excitation frequency. The problem is first formulated as a mathematical programming scheme. The systematic design discussed in this paper has significant advantages for those vibratory systems run primarily at a specific frequency.

ISSN:0098-8847    

DOI:10.1002/eqe.4290160406

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe general features of elastic‐plastic response spectra for several accelerograms that are widely used for the design buildings in Japan were studied in terms of the effects of the different hysteretic models used in the analyses. Lare fluctuations existed in the spectra for both input ground motion and the different models. The models were classified according to their strain energy‐absorbing capacities in three groups, within each of which the relevant nature of elastic‐plastic responses of the structures were similar. Finally, empirical formulae with which to estimate two measures structural damage, the ductility factors and cumulative plastic displacement normalized by the yielding displacement, wer developed for each group of hysteretic m

ISSN:0098-8847    

DOI:10.1002/eqe.4290160407

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA criterion of stability pertaining to the hybrid frequency‐time‐domain procedure is derived. It stems from the initial‐value theorem on one side and from the condition of convergence which applies to the harmonic counterpart of the procedure on the other side. The criterion depends on the dynamic stiffnesses of both the original non‐linear system and the pseudo‐linear system evaluated at the Nyquist frequency. Since at this frequency both stiffnesses are usually controlle by the mass, the criterion of stability is satisfied for most structural systems. The procedure must, however, be applie sequentially to individual time segments. The validity of this criterion is confirmed by a numerical investigation performe for a SDOF system.The solution of non‐linear dynamic problems requires consideration of implementation issues which are also discusse in the paper. The analysis of a non‐linear soil‐structure‐interaction system in which the soil's stiffness coefficients an directly defined in the frequency domain also demonstrates the accuracy of the hybrid frequency‐ti

ISSN:0098-8847    

DOI:10.1002/eqe.4290160408

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractSpecially designed arrays of strong motion seismographs located near earthquake sources are required for engineering studies of near‐source earthquake properties as well as spatial variation of seismic waves. The SMART‐1 array in Tath provides good records for this type of study. Based on the SMART‐1 array data, the analysis of the principal direction wave propagation and the space‐time correlation of some events recorded by SMART‐1 have been studied. A stoce model for predicting the differential ground movement was also developed. This stochastic model includes the effect of source characteristics, attenuation of wave passage and spatial correlation characteristics. The performance of this more discussed and compared with the ground movement recorded by the SMART‐1 array. From the present study, it is that spatial correlations do exist as seismic waves propagate across the array site. Generally, the loss of coherence is direction of propagation can be explained by energy at the same frequency exhibiting a slightly different velocity with the measurement intervals. It is also concluded that the phase velocity of seismic waves and the corner frequency of the grep displacement spectrum are controlling factors in the prediction of the root mean square of differential grep d

ISSN:0098-8847    

DOI:10.1002/eqe.4290160409

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this paper a methodology has been presented for constructing the most critical accelerogram from among a be class of candidate accelerograms for a given site and structure. This most critical accelerogram could be used to assess seismic resistance of a structure with a high level of confidence. Specifically, the method superimposes accelerograms recorded at similar sites to create the candidate accelerograms, then uses optimization and approximation techniques find the most critical accelerogram. The most critical accelerogram is defined as the one which maximizes damage is structure, as computed by non‐linear dynamic structural analysis, as well as satisfies constraints on ground parameters to ensure credibility. The damage has been defined as cumulative inelastic energy dissipation or sure of interstorey drifts. The method is applied to ten examples in the pape

ISSN:0098-8847    

DOI:10.1002/eqe.4290160410

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA previously introduced method for transmitting effective seismic excitation to a discretized soil‐structure system implemented. The method permits free‐field excitation of a linear soil system to be specified within the regie of computation, arbitrarily close to a zone that includes the (possibly non‐linear) structure and local subgrade and bae, thus eliminating the need to transmit the seismic excitation through artificial boundaries. This approach is demonse through a numerical example comprising a linear, two‐dimensional system. Some comments also are made on the rere efficiencies of various local absorbing bou

ISSN:0098-8847    

DOI:10.1002/eqe.4290160411

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY