Damage Identification Procedure for Bridge Structures with Energy Dissipation Devices

摘要

The importance of bridge structures in an era of natural and man-made risks is unquestionable. Bridges represent the keystone of an efficient transport infrastructure needed in full operation conditions when a disastrous event strikes. After natural events like the 1994 Northridge, USA, the 1995 Kobe, Japan, the 1999 Chi-Chi, Taiwan and the 1999 Duzce, Turkey earthquakes it became evident that the demand for bridge structures could greatly benefit from the application of isolation/energy dissipation techniques. A pilot project was initiated after the 1994 Northridge earthquake by the California Department of Transportation that identified the use of isolation devices as the only economical as well as convenient approach to retrofit particularly complicated structures as the bridges part of the Toll Bridge project (Mellon 1997). Most of these projects are now completed and the California experience greatly improved the confidence of bridge designers in the US about the use of this technology. An increasing number of new bridges are also protected, worldwide, with isolation solutions taking advantage of a continuous research effort in the technological improvement of these devices, testing programs, and code development. Despite the level of maturity achieved in the field of seismic isolation, open questions still remain on the durability of seismic response modification devices (SRMD) under working conditions. Devices are traditionally designed with emphasis on their extreme condition performance, like during a seismic event, but relative motion of the bridge components, service traffic loads, together with different environmental conditions raise concerns about the stability of their performance for the future. The use of new advanced material, like composites, for isolators and energy dissipators, underlines the importance of the assessment of the performance characteristics of anti-seismic devices during their service life.