SEISMIC ANALYSIS AND BEHAVIOR OF VISCOELASTICALLY DAMPED STRUCTURES

Abstract

The work described in this thesis is concerned with the general investigation of seismic load and behavior of viscoelastically damped structures under it. Also to show how the viscoelastic material affects the structure response to earthquake excitation. Simple models are included to illustrate the behavior of such systems. In this thesis two isolation devices model have been set up to study the behavior of structures with these devices . This study was undertaken to investigate the effect of viscoelastic material on framed structures under static and dynamic loads. The general non-linear behavior of multistory framed structures consisting of single bay or three bays, are studied under the effects of combined vertical and seismic dynamic loads. The computer program DRAIN-2DX was used in these analyses. The essence of this thesis, is to choose a theoretical method for modelling damping devices; based on the experimental work by S.Y. Hsu and Fafitis, and; Dario Gasprini and A. Demrial, to be used in the computation sheet calculation for design viscoelasticaliy structures under seismic load.

In this research; the viscoelastic material is used in the isolation devices (dampers), as one element of the structure components. This element can be placed at a selected connection (connection isolator device), or, selected bay ( as infill panel ) in the structures under study, as follow : Firstly; viscoelastic type connection isolator (damper) made of elastomeric material is presented in this thesis, either in the connections between beams and columns ( in case of hinged beam-column connection ), or in the bracing elements ( in case of beam-column rigid connections ). It is concluded from the experimental work, which has been done by S.Y.HUS and Fiafitis, that the durometer ( hardness parameter) of the elastomeric material is the predominant material parameter.