The current seismic design mainly focuses on the performance of structure. The human safety to earthquake shaking is considered implicitly by securing the structural performance. There exists some cases, however, of human injury due to earthquake shaking due to falling or bumping into the wall during past earthquakes. In order to ensure human safety during earthquakes, this study proposed an evaluation methodology of human behavior.
First, the relationship between human injury and floor response during earthquake is developed using a seismic analysis model of human body proposed by our previous study. The maximum displacement of center of pressure (CoP) of human body is evaluated using the human body model to estimate the possibility of falling and hitting to the wall. Furthermore, head injury criterion (HIC) score during strong shaking is evaluated as a function of the maximum velocity of head. Then, the evaluation methodology of degree of head injury and displacement of CoP based on peak floor acceleration (PFA) and representative frequency are proposed.
Then, in order to investigate the difficulty of action during earthquake shaking, the results of interview survey are shown that were conducted to the operators of the Kashiwazaki-Kariwa Nuclear Power Station to collect their experiences during the 2007 Niigataken Chuetsu-oki Earthquake. The CoPs evaluated by the above-mentioned methodology based on the strong motion records observed at the plant during the earthquake are shown to be comparable to the experiences of the operators, i.e., as the displacement of CoP increases, the human action is more difficult. This fact shows that the evaluation methodology of CoP can be used to evaluate the action difficulty of human during strong shaking.
Then, the methodology to evaluate possibility of human injury is demonstrated combining the proposed method and estimation of the overturning ratio of furniture. A result from an example case indicates that, tall furniture overturns in smaller PFA than that of human injury, if the frequency is higher than 1.0 [Hz]. Whereas if the frequency is lower than 1.0 [Hz], PFA for overturning of tall furniture is almost equivalent to that of human injury.
Finally, seismic design framework for building that focuses on human injuries during earthquakes was proposed. It is demonstrated that integrated evaluation of possibility of injury due to falling down on the floor, bumping into the wall, and overturning of the furniture as well as action difficulty due to shaking can be conducted using the proposed method to discuss the design criteria of the building for securing human safety.
