摘要:

AbstractA modified truncated cone model is used to calculate approximately the dynamic response of a disk on the surface of a soil layer resting on flexible rock. The procedure is analogous to that for a layer on rigid rock, the only modification being that the reflection coefficient —α at the layer–rock interface is no longer equal to −1. The modified value of α can be determined straightforwardly by considering one‐dimensional wave propagation along the cone. The low‐ and high‐frequency limits lead to a frequency‐independent α, which allows the dynamic analysis to be performed directly in the familiar time domain. This cone represents a wave pattern with amplitude decay and also incorporates the reflection at the free surface and the reflection‐refraction at the layer–rock interface. The results for the static stiffness of the disk are highly accurate for a wide range of geometrical and material properties of the layer and the rock. For the dynamic stiffness the agreement with the exact solu

ISSN:0098-8847    

DOI:10.1002/eqe.4290220302

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBy coupling FEM and BEM, a numerical method was developed for dynamic response analyses of dam–foundation–reservoir systems in the time domain. During formulation, the weighted residual procedure was applied to the coupling of several equations of motion for solid and fluid in the FE and BE regions, and an algorithm similar to the Newmark beta procedure was finally obtained. The algorithm is advantageous in that it takes into account all the effects of dam–foundation, dam–reservoir and reservoir–foundation interactions, as well as of the absorption of both elastodynamic and hydrodynamic waves at the boundaries of the foundation and the reservoir. To demonstrate the validity of the present method, the impulsive response of a dam–foundation–reservoir system was calculated using the algorithm, and showed a good agreement with the existing results obtained by othe

ISSN:0098-8847    

DOI:10.1002/eqe.4290220303

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractTime delay problem and its compensation in active control of civil engineering structures were studied. It has been shown by stability analysis of a SDOF system with time delayed feedback that the maximum allowable time delay depends not only on the natural period of the structure but also on feedback gains. We have demonstrated by numerical simulation that the performance of the control system degrades significantly when the time delay is close to this value and it even becomes unstable when time delay is greater than or equal to this value. The maximum allowable time delay decreases with decrease in natural period of the structure as well as with increase in active damping. The paper presents a technique for compensation by modelling time delay as transportation lag. This method ensures the stability of the controlled system as well as the desired response reduction.

ISSN:0098-8847    

DOI:10.1002/eqe.4290220304

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA time domain boundary element in a cylindrical co‐ordinate system is developed for the analysis of wave propagation in a layered half‐space. The field quantities (displacements and tractions) are expressed as products of Fourier series in the circumferential direction and as linear polynomials in the other spatial directions. An integral equation is written for each layer as an independent domain, and these equations are then assembled into a general equation by virtue of compatibility and equilibrium conditions between the interfaces. Examples of three‐dimensional wave propagation in the layered half‐spaces due to various forms of surface and inner‐domain excitations are reported to demonstrate the accuracy and versatility of t

ISSN:0098-8847    

DOI:10.1002/eqe.4290220305

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe study of the torsional response of buildings in the inelastic range of behaviour is of great interest since the ability of structures to resist strong earthquakes mainly relies on their ductility and capacity for energy dissipation. Furthermore, an examination of the performance of structures during past earthquakes demonstrates that plan‐asymmetric buildings suffered greater damage due to torsional response. The paper deals with this subject by analysing a model which idealizes a one‐storey building with resisting elements oriented along two perpendicular directions. In addition to the parameters of the elastic behaviour, the inelastic system response depends on full yield capacity and plan‐wise strength distribution. The influence of the criterion adopted for the design of resisting elements on local ductility demand and damage has been evaluated by parametric analysis. In particular, a comparison has been carried out between systems with equal design levels for all elements and systems with design levels dependent on the element location. For a given elastic behaviour and total capacity, the strength distributions in plan have been defined which minimize ductility demand and structural damage. Finally, based on these findings, responses from models designed according to several seismic codes have been com

ISSN:0098-8847    

DOI:10.1002/eqe.4290220306

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA new base isolation method is proposed for the protection of structures. Because of the efficiency of the isolation devices, the isolated structure may be made to remain elastic throughout major earthquakes. This device consists of two sets of mutually orthogonal free rolling rods under the basement of the structure. Since the coefficient of rolling friction of the rods is very small in practice, the structure can be isolated excellently from the support excitation. In this paper, the analytical method and the response of the isolated system for different parameters, such as the periods of the structure, the coefficient of rolling friction and the masses of rolling rods, are presented. The results indicate that the proposed method is excellent in isolating the structure from support excitations, as expected.

ISSN:0098-8847    

DOI:10.1002/eqe.4290220307

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220308

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220309

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220310

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220301

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY