A Simple Method for Determining the Level of Damage to a Medium/Low-Rise Steel-Frame Building after an Earthquake Based on Energy Balance

Abstract

We propose a simple method for determining, based on energy balance, the degree of damage to a medium/low-rise steel-framed building after an earthquake, and confirm that the method is likely to be usable in practice. We calculated total energy input, comprising foreshocks, the mainshock and aftershocks, using the cumulative energy spectrum. In addition, we compared results from time history response analysis using seismic vibration for design purposes as input with the results from the method we propose, and found that both methods yielded fairly consistent results, with differences in the number of stories or seismic vibration having little impact. Using observed waveforms from the Kumamoto earthquake, we examined the applicability of the method based on differences in earthquake order of occurrence and phase. With this method, we were able to track the progress with the degree of damage according to earthquake order of occurrence.