Shin-ichi Tsuburaya

Development and Validation of a Potential-Based Model for City Evacuation in Post-Earthquake Fires

A computational model for the city evacuation of residents in post-earthquake fires has been developed. When a major earthquake affects a city in Japan, a tremendous number of evacuees are likely to escape in an urban area from hazards due to urban fires following the earthquake. The proposed model is based on the concept of potential. In this concept, an evacuee travels toward a descending direction of potential in the same manner that water runs from a high point to a low point. The potential is calculated from such hazard levels as the intensity of thermal radiation and the temperature rise caused by wind-blown fire plumes. In this paper, we simulate the evacuation behavior of residents in the 1923 Kanto earthquake fires to validate the proposed model. The number of fatalities estimated by the model is in reasonable agreement with the number of fatalities reported from the survey after the fires.

Study on Fire Plume Behavior in Vertical Shafts of Buildings

Model experiments are conducted on a vertical shaft with openings installed uniformly in the vertical direction along the vertical shaft and on a vertical shaft where one opening is present in the bottom floor and another one floor above. Study of these models helps to elucidate phenomena such as the stack effect by working from fundamental knowledge of the behavior of hot airflows in vertical shafts. The following results were obtained: (1) the temperature distribution within the vertical shaft decreases from the lower part toward the upper part inside the vertical shaft, and (2) \( \Delta {T}_{s,F}/{T}_{\infty } \) and \( {Q}_{z_F}^{*} \) have a largely proportional relationship, independent of the opening conditions and the position of the fire source. Furthermore, a prediction formula for the temperature distribution inside the vertical shaft is derived from the results.