10-27-2012, 03:58 PM
Seismic Retrofitting Manual for Highway Structures: Part 1 - Bridges
Author: Buckle, Ian University of Nevada, Reno Friedland, Ian Mander, John Martin, Geoffrey University of Southern California, Los Angeles Nutt, Richard Power, Maurice | Size: 15.45 MB | Format: PDF | Quality: Unspecified | Publisher: Multidisciplinary Center for Earthquake Engineering Research | Year: 2006 | pages: 656
The main objective of this research was to assess the seismic vulnerability of typical pre-1975 Washington State Department of Transportation (WSDOT) prestressed concrete multi-column bent bridges. Additional objectives included determining the influence of soil-structure-interaction on the bridge assessment and evaluating the effects of non-traditional retrofit schemes on the global response of the bridges. Overall this research highlighted the vulnerability of non-monolithic bridge decks and shear-dominated bridThis manual, which is comprised of two parts, represents the most current state-of-practice in assessing the vulnerability of highway structures to the effects of earthquakes, and implementing retrofit measures to improve performance. Part 1 of this manual focuses on highway bridges, and is a replacement for the Federal Highway Administration (FHWA) publication "Seismic Retrofitting Manual for Highway Bridges" which was published in 1995 as report FHWA-RD-94-052. Revisions have been made to include current advances in earthquake engineering, field experience with retrofitting highway bridges, and the performance of bridges in recent earthquakes. It is the result of several years of research with contributions from a multidisciplinary team of researchers and practitioners. In particular, a performance-based retrofit philosophy is introduced similar to that used for the performance-based design of new buildings and bridges. Performance criteria are given for two earthquake ground motions with different return periods, 100 and 1000 years. A higher level of performance is required for the event with the shorter return period (the lower level earthquake ground motion) than for the longer return period (the upper level earthquake ground motion). Criteria are recommended according to bridge importance and anticipated service life, with more rigorous performance being required for important, relatively new bridges, and a lesser level for standard bridges nearing the end of their useful life. Minimum recommendations are made for screening, evaluation and retrofitting according to an assigned Seismic Retrofit Category. Bridges in Category A need not be retrofitted whereas those in Categories B, C and D require successively more rigorous consideration and retrofitting as required. Various retrofit strategies are described and a range of related retrofit measures explained in detail, including restrainers, seat extensions, column jackets, footing overlays, and soil remediation.ge columns in pre-1975 WSDOT prestressed concrete multi-column bent bridges as well as the importance of including soil-structure-interaction, calibrating the force/displacement characterization of the columns to experimental test data and detailed modeling of the bridges such as expansion joint/girder interaction. In the end, the seismic assessment of bridges is a cost/efficiency issue. Each bridge is different, therefore, investing in improved analyses up front will enable an efficient use of the limited funds for bridge improvement, resulting in a significant savings overall.
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