Estimation of high-rise building response in metro Manila,Philippines,during the 2019 central Luzon earthquake based on video data analysis

Abstract

The 2019 Mw 6.1 Central Luzon earthquake generated significant long-period ground motions in Metro Manila, the Philippines, affecting high-rise buildings with non-structural damage on rooftop water storage facilities. Due to the unavailability of direct instrumental measurements, this study employed video data analysis to estimate the response of the affected buildings during the earthquake. The natural periods of four analyzed buildings were estimated in the range of 3.3–5.2 seconds, corresponding to the period range (3–6 seconds) of the observed ground motions with high spectral amplitudes in the area. The time-variant features of the ground motion records revealed the dominant influence of surface waves at periods exceeding 3 seconds. While the estimated acceleration and displacement response levels were relatively small in the period range of the affected buildings, the prolonged duration of surface waves sustained the liquid sloshing oscillations inside the water tanks and suggested to lead the observed non-structural damage. These findings suggest that large-scale structures with natural periods in the 3- to 6-second range, typically corresponding to 30–60 story buildings, may be particularly susceptible to resonance effects during large earthquakes and at risk of prolonged shaking with sloshing effects and nonstructural damage even during moderate earthquakes in this region. By using video data as an alternative data source, this study provides the first assessment of high-rise building response to long-period motions in Metro Manila, bridging a knowledge gap in a region with limited availability of data from building instrumentation. Further investigations and potential updates to local seismic provisions are suggested to address the effects of long-period surface waves on high-rise buildings in Metro Manila.