Achieving Operational Seismic Performance of RC Bridge Bents Retrofitted With Buckling-Restrained Braces PDF Download
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Author: Publisher: ISBN: Category : Bridges Languages : en Pages : 363
Book Description
Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level.
Author: Publisher: ISBN: Category : Bridges Languages : en Pages : 363
Book Description
Typical reinforced concrete (RC) bridges built prior to 1970 were designed with minimum seismic consideration, leaving numerous bridges highly susceptible to damage following an earthquake. In order to improve the seismic behavior of substandard RC bridges, this study presents the seismic performance of reinforced concrete bridge bents retrofitted and repaired using Buckling-Restrained Braces (BRBs) while considering subduction zone earthquake demands. In order to reflect displacement demands from subduction ground motions, research studies were conducted to develop quasi-static loading protocols and then investigate their effect on structural bridge damage. Results suggested that subduction loading protocols may reduce the displacement ductility capacity of RC bridge columns and change their failure mode. The cyclic performance of reinforced concrete bridge bents retrofitted and repaired using BRBs was experimentally evaluated using large-scale specimens and the developed loading histories. Three BRB specimens were evaluated with the aim of assessing the influence of these components on the overall performance of the retrofitted and repaired bents. Additionally, subassemblage tests were conducted in an effort to study the response of these elements and to allow for refined nonlinear characterization in the analysis of the retrofitted and repaired systems. The results of the large-scale experiments and analytical studies successfully demonstrated the effectiveness of utilizing buckling-restrained braces for achieving high displacement ductility of the retrofitted and repaired structures, while also controlling the damage of the existing vulnerable reinforced concrete bent up to an operational performance level.
Author: Publisher: ISBN: Category : Bridges Languages : en Pages : 36
Book Description
This case study investigates the buckling restrained braces (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.
Author: A. K. M. Golam Murtuz Publisher: ISBN: Category : Concrete bridges Languages : en Pages : 109
Book Description
The main objective of this research was to quantify the material strain limits for seismic assessment of existing sub-standard reinforced concrete bridge bents considering operational performance design criteria. Limited confidence exists in the current material strain limit state for operational performance criteria due to lack of experimental results considering the typical detailing of Oregon bridges and the cumulative damage effect resulting from an anticipated long-duration Cascadia Subduction Zone (CSZ) event. Component details for bridge bents such as geometry and reinforcing details were determined through a statistical analysis of available bridge drawings built prior to 1990 in the State of Oregon. Three full-scale bridge bent column-footing subassembly specimens were constructed and subjected to reverse cyclic lateral deformations utilizing a traditional loading protocol and a protocol representing the demands expected from a CSZ earthquake. The tests were designed so that variable axial loading could be applied in order to simulate the secondary effects experienced in a column that is part of a multi-column bent during an earthquake event. Material strains along with global and local deformation quantities were measured with a suite of external and internal sensors mounted to and embedded in the specimens. Despite having sub-standard seismic detailing, all three specimens exhibited ductile behavior under reverse cyclic lateral loading, achieving a minimum displacement ductility of 8.0. The obtained results also suggest that the material strain limits currently used for the seismic evaluation of existing bridges in Oregon considering operational performance criteria are conservative, but may still require further experimental validation. Finally, strain limits based on previous research at Portland State University (PSU) were compiled and combined with the results from this study to propose recommended strain limit values.
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Author: Claudia P. Pulido-Collantes
Author: David I. McLean
Author: A. K. M. Golam Murtuz
Author: Mohamed Ragab Elbahar
Author: Matthew John Schoettler
Author: Michael Pollino
Author: Joel Lanning