Seismic assessment and retrofit of bridge column footings

This paper describes theoretical and experimental studies related to seismic assessment and retrofit of bridge column footings. One ''as built'' model column footing and three retrofit model column footings have been tested under simulated seismic actions. Test results of the ''as built ''footing indicated that column/footing joint shear failure is a potential danger to existing bridge structures. Test results also indicated that if there is lu, dependable tensile capacity in the pile/footing connection, a rocking behavior may dominate pier response, minimizing damage to footing and column. Model column footings retrofit using current retrofit standards developed relatively stable hysteretic responses up to moderate ductility level However experimental observations and theoretical analyses based on a strut-and-tie model and yield-line theory indicated that with current footing retrofit design, which lacks the consideration for joint shear design, the reinforced concrete overlay may not develop a fully effective postcracking mechanism Improved retrofit derails including long dowels to insure development of an effective joint shear-resisting mechanism are proposed and verified by experimental results.