The design of bridge seismic retrofit interventions can be based on traditional techniques aimed to increase strength and/or ductility or on the use of devices able to modify the dynamic structural response (isolators) or to increase the dissipative nature of the structure (dampers). This innovative approach can represent a cost benefit option with respect to traditional techniques. On the other hand the reliability of the design and the safety of the bridge are strongly dependent on the design and fabrication accuracy of the device, as well as on a correct numerical simulation of its performance. The latter depends on the knowledge of the device seismic behavior in real conditions and so on the availability of full scale experimental data. In this paper a simplified model of an elasto-plastic dissipating device (ALGA EP) is presented. The device is composed of two main components: a central shock transmission unit and a number of C shaped elasto-plastic dissipating components. The proposed distributed element model is based on an assembly of non linear spring elements each one modelling a certain number of dissipating C shaped elements. The parameters of the model can be calculated as function of the mechanical characteristics of the single C shaped element. The response of the model to imposed displacements time histories have been compared to responses recorded on the device during displacement controlled tests carried out on the Caltrans SRDM test facility located at the University of California San Diego campus. Comparison between experimental and analytical displacements and restoring forces time histories show very good agreement. Peak displacements and restoring forces were estimated by the model with a mean error of about 5% while the error in the assessment of the energy dissipated per cycle ranges between 1% and 10%.

A distributed elements model for bridge dissipating elasto-plastic devices

LIMONGELLI, MARIA GIUSEPPINA
2002-01-01

Abstract

The design of bridge seismic retrofit interventions can be based on traditional techniques aimed to increase strength and/or ductility or on the use of devices able to modify the dynamic structural response (isolators) or to increase the dissipative nature of the structure (dampers). This innovative approach can represent a cost benefit option with respect to traditional techniques. On the other hand the reliability of the design and the safety of the bridge are strongly dependent on the design and fabrication accuracy of the device, as well as on a correct numerical simulation of its performance. The latter depends on the knowledge of the device seismic behavior in real conditions and so on the availability of full scale experimental data. In this paper a simplified model of an elasto-plastic dissipating device (ALGA EP) is presented. The device is composed of two main components: a central shock transmission unit and a number of C shaped elasto-plastic dissipating components. The proposed distributed element model is based on an assembly of non linear spring elements each one modelling a certain number of dissipating C shaped elements. The parameters of the model can be calculated as function of the mechanical characteristics of the single C shaped element. The response of the model to imposed displacements time histories have been compared to responses recorded on the device during displacement controlled tests carried out on the Caltrans SRDM test facility located at the University of California San Diego campus. Comparison between experimental and analytical displacements and restoring forces time histories show very good agreement. Peak displacements and restoring forces were estimated by the model with a mean error of about 5% while the error in the assessment of the energy dissipated per cycle ranges between 1% and 10%.
2002
Proc. of the 3rd World Conference on Structural Control. Como, 7-12 Aprile 2002.
dissipating elasto-plastic devices; bridge; distributed elements model
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/252731
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