ABSTRACT
Ayala Bridge, in the center of Manilla, is a steel arch bridge built in the 1950s. It is comprised of simply supported steel bridges constructed with 3 trusses connected together. The bridge has to be retrofitted for conformity to new codes (traffic and seismic). The retrofitting solution designed by Freyssinet was chosen because of its economy when considering both deck and foundations: it consists of minimizing the current seismic loads on piers and abutments, to get them lower than actual loads seen in the past under historic seismic and typhoon. Longitudinally, the 2 decks are linked together and extended with beams and new piles: the overall structure is working as a frame. Transversally, some seismic devices are placed. The overall steel structure is then strengthened using additional steel profiling and prestressing. Major parts of the work has been done with no traffic interruption at all.
