摘要:

AbstractA boundary integral formulation is presented and applied to model the ground motion on alluvial valleys under incident P, S and Rayleigh waves. It is based on integral representations for the diffracted and the refracted elastic waves using single‐layer boundary sources. This approach is calledindirectBEMin the literature as the sources' strengths should be obtained as an intermediate step. Boundary conditions lead to a system of integral equations for boundary sources. A discretization scheme based on the numerical and analytical integration of exact Green's functions for displacements and tractions is used. Various examples are given for two‐dimensional problems of diffraction of elastic waves by soft elastic inclusion models of alluvial deposits in an elastic half‐space. Results are displayed in both frequency and time domains. These results show the significant influence of locally generated surface waves in seismic response and suggest approximations of practical interest. For shallow alluvial valleys the response and its resonant frequencies are controlled by a coupling mechanism that involves both the simple one‐dimensional shear beam model and the propagation of surfac

ISSN:0098-8847    

DOI:10.1002/eqe.4290220402

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents a formulation for earthquake resistant design of optimum hybrid isolation systems for sensitive equipment protection. The hybrid system under consideration consists of laminated rubber bearings, viscodampers and a set of actuators which, grounded on the main structural system, deliver forces on the basement of the isolated substructure mounted on the main structural system. An integrated design procedure for the passive and active components of the isolation system is developed aiming at acceleration reduction under random excitation. Linear models are used for the isolated structure, the main structural system and the isolation system. Fractional derivative Maxwell elements are used to model the mechanical behaviour of the viscodampers. The active component of the isolation system applies forces proportional to the absolute velocity of the isolated piece of equipment. Constraints in the deformation capacity of the isolators as well as constraints in the capacity of the actuators are considered for the design of an optimal hybrid isolation system. Simple numerical examples are developed herein to illustrate the design procedure. The superiority of hybrid systems over passive systems in reducing acceleration response is demonstrated.

ISSN:0098-8847    

DOI:10.1002/eqe.4290220403

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents an advanced non‐linear model developed for the analysis of composite steel/concrete frame structures subjected to cyclic and dynamic loads. The formulation consists of beam‐column cubic finite elements accounting for geometric non‐linearities and material inelasticity. The non‐linear cyclic concrete model considers confinement effects and the constitutive relationship for steel includes the effect of local buckling and variable amplitude cyclic degradation. The model is calibrated and compared with experimental data from cyclic and pseudo‐dynamic tests conducted by the writers on a new ductile partially‐encased composite beam‐column. The accuracy and efficiency of the developed model are demonstrated through the correlation between the experimental results and analytical simulations. In a companion paper, the model is used to conduct parametric studies leading to important conclusions for ductility‐based earthquake

ISSN:0098-8847    

DOI:10.1002/eqe.4290220404

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this paper, an advanced analytical model proposed and verified in a companion paper (Part I: Analytical model) is used to conduct parametric investigations of ductile partially‐encased composite beam‐columns. Particular attention is given to a new configuration of composite member developed and tested at Imperial College. A detailed account of the analytical results is given, and the most significant observations are highlighted and discussed. Quantitative assessments of plastic moment capacity, rotation and displacement ductility and plastic hinge length are undertaken. The implications of the main findings on the seismic design process are also presented. Finally, a procedure for ductility‐based design according to modern codes of practice is out

ISSN:0098-8847    

DOI:10.1002/eqe.4290220405

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220406

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220407

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY

ISSN:0098-8847    

DOI:10.1002/eqe.4290220401

出版商:John Wiley&Sons, Ltd    

年代:1993

数据来源: WILEY