Seismic vulnerability assessment of Palacio del Gobernador using fragility curve

Palacio del Gobernador is a 48-year standing 9-storey building located at Intramuros, Manila. Its location of about 10.4 km from the West Valley Fault makes it vulnerable to seismic activities that are expected to occur at the fault, including the “Big One.” This study assessed the seismic vulnerability of the Palacio del Gobernador by generating and analyzing its seismic fragility curves. The researchers generated the digital model of the building using SAP2000. The structural model was then subjected to a Pushover Analysis. Ground motion data of local and foreign earthquakes were collected from DOST-PHIVOLCS and PEER. These were subjected to Response Spectrum Analysis using PRISM in order to generate their response spectra. The results of the two analyses were used in the Capacity Spectrum Method using SAP2000 to generate damage rank frequencies. These values were then used to generate the seismic fragility curves. The values in these curves revealed that, under a 0.4g PGA ground motion, the Palacio del Gobernador has a 49-50% probability of no damage, 18-20% probability of slight damage, 9-11% probability of moderate damage, 6-7% probability of extensive damage, and a 5% probability of total collapse. In particular, the probability of reaching the exceeding extensive damage is under 10%, which is the reference value for 0.4g PGA ground motion based on Section 208.5.3.2 of the NSCP 2015. These findings indicate that the Palacio del Gobernador is resilient against extensive damage when subjected to an earthquake that is comparable to the “Big One” and does not require additional measures to mitigate potential earthquake damage.