摘要:

AbstractA method is presented whereby the response spectrum may be used to predict the response of equipment mounted on an isolation system with non‐linear motion limiting constraints. The results of the approximate method are compared with results obtained by direct numerical integration for a representative piece of equipmen

ISSN:0098-8847    

DOI:10.1002/eqe.4290060602

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe soil‐structure system is modelled as a uniform vertical beam, which terminates in a base or foundation mass; this mass is attached to the surface of an elastic half‐space. Using known force‐displacement relations for the coupled vibrations of a rigid disc on an elastic half‐space, the natural frequencies and response to a transverse harmonic force, applied at the tip of the beam, are determined through a continuum approach. Effectively the problem reduces to a beam with frequency‐dependent boundary conditions. A parametric study shows that changes in the three ratios, Young's modulus for the beam to that for the half‐space, the radius of the base mass to the length of the beam,L, and the second moment of area of the beam cross‐section/L4, cause large variations in the maximum response, which due to interaction can be considerably smaller or larger than that for a comparable fixed‐base cantilever beam. This dynamic behaviour can be explained by considering the variation of natural frequencies, mode shapes and modal damping factors with these ratios.A brief study of the response of the structure to a free‐field harmonic acceleration, applied at the soil‐structure interface, suggests that interaction depends upon material and geometric properties of the system, rather than on the natur

ISSN:0098-8847    

DOI:10.1002/eqe.4290060603

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractThe structure is idealized as a uniform slender beam of circular cross‐section which supports a rigid tip mass and which is connected at its base to a rigid foundation mass, the latter being attached to the surface of a visco‐elastic half‐space. An analytical solution for harmonic response of the partially submerged structure is obtained in terms of the normal modes of the corresponding structurein vacuo.This is achieved by introducing fluid‐structure coupling into the model. A similar structural model has been described in a companion paper and used to study soil‐structure interaction. Numerical results show the dependence of response on various parameters and contribute towards a better understanding of the dynamics of off‐s

ISSN:0098-8847    

DOI:10.1002/eqe.4290060604

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

摘要:

AbstractBoth harmonic and seismic responses of several idealized offshore oil pipelines in proximity to the sea‐bed have been studied in this paper by using a digital computer algorithm. In this, spatial discretization was based on finite elements, with nodal lumped masses, while a step‐by‐step explicit forward integration scheme was implemented for processing in the time domain.A study of the basic system parameters shows that pipe response to a horizontal transverse ground excitation is mainly affected by the clearance between the pipe and the sea‐bed, pipe geometry and its end‐restraints. Results also show that the overall effect of non‐linear pressure drag is not substantial.Relevant fluid dynamic aspects affecting system response as well as possible effects of marine growth on pipe surface and structural/chemical degradation of the pipe coating are als

ISSN:0098-8847    

DOI:10.1002/eqe.4290060605

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290060606

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290060601

出版商:John Wiley&Sons, Ltd    

年代:1978

数据来源: WILEY