Seismic Response of Reinforced Concrete Bridge Pier Walls in the Weak Direction

Keywords: Bridge pier walls.  Seismic response.  Out of plane response.  Displacement ductility capacity.  Failure modes.  Parametric analysis.  Confinement reinforcement.  Moribe viaduct.  Kobe, Japan earthquake, January 17, 1995.  Hanshin-Awaji, Japan earthquake, January 17, 1995.  Hyogo-ken Nanbu, Japan earthquake, January 17, 1995.

Abstract: This research consists of an experimental and and an analytical study.  The experimental study evaluates the out-of-plane seismic behavior of representative bridge pier walls that exist in the US.  The analytical study develops and calibrates an analytical model to determine the seismic response of bridge pier walls.  An approach is developed that relates the displacement ductility capacity to the amount of confinement steel.  A comprehensive bridge pier wall survey was conducted to collect information about existing typical pier walls in the US.  A statistical analysis was performed on the collected data to select test parameters and specimens.  Seven specimens were designed, built, and tested in the experimental study under slow cyclic loads.  An analytical model was developed and calibrated.  A computer program called PIER was written to implement the analytical model.  A parametric study was conducted to extend the seismic response study to bridge pier wall cases that were not tested experimentally.  The parameters were the ratio of the wall height to thickness, the vertical steel ratio, the confinement steel ratio, and the axial load index.  Pier wall cases that need retrofit were identified based on the expected seismic response.  A practical approach to relate the confinement reinforcement in the plastic hinge zones of bridge pier walls to the displacement ductility capacity was developed based on the results of the parametric study.  The displacement ductility capacity of six typical pore walls that contained confinement steel designed using the available code provisions was calculated using the proposed approach.  A comparison of the resulting ductilities was made to identify design provisions that lead to best level performance.