Portland State University. Department of Civil & Environmental Engineering
Date of Award
Master of Science (M.S.) in Civil & Environmental Engineering
Civil and Environmental Engineering
Bridges -- Retrofitting -- Oregon -- Case studies, Buckling (Mechanics), Earthquake resistant design, Reinforced concrete -- Earthquake effects, Concrete bridges -- Earthquake effects, Reinforced concrete construction -- Design and construction
Many highway bridges in Oregon have been designed with minimal considerations for seismic hazard and are in need of retrofit. Although buckling restrained braces (BRBs) are not necessarily a new concept, using them to seismically retrofit bridges is. This case study investigates the BRB retrofit concept as compared to traditional retrofit measures for a sample of typical vulnerable bridges in Oregon. The objectives of evaluating these cases were to determine the feasibility of the concept both in terms of performance as well as construction costs. This study builds on the ongoing research at Portland State University into the development of the fuse retrofit concept for Oregon highway bridges and follows recently completed large scale laboratory tests of BRB retrofitted bents.
Three reinforced concrete highway bridges were selected from the Oregon Department of Transportation (ODOT) bridge inventory to represent a typical layout that characterizes numerous bridges that are seismically vulnerable across Oregon. The three bridges included varying skews and pier cap beam configurations to determine the impact of these characteristics on the seismic retrofit implementation and performance. Seismic vulnerability assessments of the existing bridges were conducted in accordance with the guidelines of the ODOT Bridge Design and Drafting Manual (BDDM). Preliminary designs were then developed considering conventional retrofit measures as well as the newly proposed retrofit measure utilizing BRBs as ductile fuses. Comparison was then made among the bridges relative to their expected seismic performance and estimated retrofit construction cost. The results of the analyses have shown that bridge retrofits using BRBs can be not only feasible, but also a cost effective retrofit strategy and should be part of the designer’s toolbox when considering bridge seismic retrofits.
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Miotke, Michael K., "Seismic Retrofit Case Study of Reinforced Concrete Bridges with Buckling Restrained Braces" (2017). Civil and Environmental Engineering Master's Project Reports. 33.