Development of Vertical-to-Horizontal Response Spectrum Ratio Model for Taiwan

Development of Vertical-to-Horizontal Response Spectrum Ratio Model for Taiwan

According to the current building seismic design code, the design vertical ground motion response spectrum can be derived by multiplying the horizontal ground motion response spectrum with the design vertical-to-horizontal response spectrum ratio(V/H ratio). The design V/H ratio is a period-independent constant of 2/3 for target sites nearby the active fault and 1/2 for other target sites. However, recent studies have shown that the V/H ratio strongly depends on the earthquake magnitude, distance and site condition of the ground motion, and structural period. They also found that the V/H ratio of some periods may be larger than 1 for the near-fault soil site struck by an earthquake of large magnitude. In this study, the horizontal and vertical ground motion characteristics were investigated simultaneously, and a V/H ratio model applicable for Taiwan was developed. The results of this study can provide valuable information for the revision of the design V/H ratio in the current seismic design code.