Seismic Performance and Retrofitting of Steel Bearings


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Title: Seismic Performance and Retrofitting of Steel Bearings

Author(s): J. B. Mander, D. K. Kim, and S. S. Chen

Publication: Special Publication

Volume: 164


Appears on pages(s): 323-336

Keywords: anchor bolts; bridge bearings; earthquake-resistant structures; elastic analysis; reinforced concretes; Structural Research

Date: 11/1/1996

The seismic performance of high type steel bridge bearings of both the fixed and expansion/rocker type were investigated. Simple seismic retrofit strategies were proposed and investigated experimentally. It was shown that by retrofitting existing high type steel bridge bearings, it is possible to provide sufficient strength and displacement capability to withstand substantial ground shaking. The weak link in the chain of force transmission may thus become the anchor bolts and/or the reinforced concrete pedestal. To understand the influence of the reinforced concrete pedestal and mild steel anchorage on the overall behavior of a high type fixed bearing assembly, a full scale reinforced concrete cap beam with pedestals was constructed. The rest results demonstrate the importance of considering the flexibility and strength of the concrete pedestal-anchor bolt system. As a retrofit method for the damaged reinforced concrete pedestal, a steel jacketing retrofit wrapped around the damaged reinforced concrete pedestal and bearing was investigated. Once retrofitted, it is shown that essentially elastic behavior may be expected in an earthquake.