Seismic evaluation and retrofit with steel jackets of reinforced concrete bridge piers detailed with lap-splices

Abstract

Recent earthquakes around the world have confirmed the poor seismic behavior of reinforced concrete bridge piers incorporating typical pre-1971 reinforcement details. Since the 1971 San Fernando earthquake in California, procedures to evaluate accurately the flexural and shear behavior of reinforced concrete bridge piers, as well as retrofit techniques to address economically the most common deficiencies, have been elaborated. In eastern Canada, the majority of reinforced concrete bridge structures incorporate piers with similar reinforcement details as those that suffered severe damage, or collapse, during recent earthquakes in California and Japan. Very little research, however, has been conducted on the seismic behavior of these structures, which often exhibit complex cross-sectional geometries and lap-splices in the plastic hinge region. This paper presents a contribution towards a better understanding of the seismic behavior and retrofit of reinforced concrete bridge piers in eastern Canada through quasi-static tests performed on five 1/3.65-scale pier models of an existing bridge structure in the Montreal region. The first specimen was tested in its existing conditions, while the four others were retrofitted with steel jackets. The geometry of the jacket, the size of the gap at the base of the pier, and the properties of the fill material between the jacket and the original cross section were investigated in these last four tests. A numerical model, considering the bond-slip between the concrete and the longitudinal reinforcement, is proposed to simulate the experimental results. Key words: bond-slip, bridge piers, ductility, hysteresis loops, lap-splices, seismic retrofit, steel jackets.