A new procedure to retrofit existing structures subjected to seismic excitation is proposed. The main features of this procedure are to reduce maximum acceleration and associated forces in buildings subjected to seismic excitation by reducing their strength (weakening). The weakening retrofit, which is an opposite strategy to strengthening, is particularly suitable for buildings having overstressed components and foundation supports or having weak brittle components. However, by weakening the structure large deformations are expected. Supplemental damping devices however can control the deformations within desirable limits. The structure retrofitted with this strategy will have, therefore, a reduction in the acceleration response and a reduction in the deformations, depending on the amount of additional damping introduced in the structure. An illustration of the above strategy is presented here through an evaluation of the inelastic response of the structure through a spectral procedure, modified to fit structures with additional damping. The results are evaluated also with a more conventional dynamic nonlinear analysis. Both methods show that the retrofit solution is feasible and simplified techniques can be used for evaluation. A sensitivity analysis has also been carried out to evaluate the effectiveness of the retrofitting method in presence of uncertainties in the analysis, in the construction properties and in the ground motions through fragility analysis.
Retrofit of structures: strength reduction with damping enhancement / A.M. Reinhorn; S. Viti; G. Cimellaro. - ELETTRONICO. - (2005), pp. 1-14. (Intervento presentato al convegno 37th UJNR panel meeting on wind and seismic effects tenutosi a Tsukuba, Japan nel May 16-21).
Retrofit of structures: strength reduction with damping enhancement
VITI, STEFANIAWriting – Original Draft Preparation
;
2005
Abstract
A new procedure to retrofit existing structures subjected to seismic excitation is proposed. The main features of this procedure are to reduce maximum acceleration and associated forces in buildings subjected to seismic excitation by reducing their strength (weakening). The weakening retrofit, which is an opposite strategy to strengthening, is particularly suitable for buildings having overstressed components and foundation supports or having weak brittle components. However, by weakening the structure large deformations are expected. Supplemental damping devices however can control the deformations within desirable limits. The structure retrofitted with this strategy will have, therefore, a reduction in the acceleration response and a reduction in the deformations, depending on the amount of additional damping introduced in the structure. An illustration of the above strategy is presented here through an evaluation of the inelastic response of the structure through a spectral procedure, modified to fit structures with additional damping. The results are evaluated also with a more conventional dynamic nonlinear analysis. Both methods show that the retrofit solution is feasible and simplified techniques can be used for evaluation. A sensitivity analysis has also been carried out to evaluate the effectiveness of the retrofitting method in presence of uncertainties in the analysis, in the construction properties and in the ground motions through fragility analysis.File | Dimensione | Formato | |
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