Fragility curves for buildings based on damage data in uki city due the 2016 kumamoto earthquake

A series of earthquakes hit Kumamoto Prefecture in Kyushu Island, Japan, on April 14 and 16, 2016. A large number of buildings, mostly wooden houses, were damaged. This study developed fragility curves of buildings using the damage survey data provided by the Uki City government. The damage ratios of buildings were investigated from the viewpoints of the structural material and the construction period. As the result, the damage ratio of wooden buildings was found to be larger than those of other structural materials, and the damage ratios of major, moderate+, and moderate-got smaller as the construction period became newer. Empirical fragility curves of buildings for Uki City were constructed based on the damage survey data and the estimated peak ground velocity (PGV). Compared with the result of the previous study for Mashiki Town due the 2016 Kumamoto earthquake, the major damage ratios of wooden buildings for Uki City was shown in a lower level than those for Mashiki Town in the same PGV. The fragility curves for Uki City were obtained using the damage survey data in the smaller PGV range than that for Mashiki Town, thus the regression results reflected the damage trend in the small PGVs. The fragility curves for Uki City and Mashiki Town due the 2016 Kumamoto earthquake were compared with those for Nishinomiya City and Nada Ward due the 1995 Kobe earthquake. As the result, it was observed that the fragility curves for the Kumamoto earthquake showed lower damage ratios than those for the Kobe earthquake.