Yuka Ikehata

An Examination Of Feasibility Of Elevator Evacuation Based On Risk Assessment

In Japan, occupants should usually escape by stairways, not by elevator cars in case of a building fire. However, it is reported that occupants used elevator cars for evacuation in several major fires such as the Hiroshima Motomachi High-rise Apartments Fire that occurred on October 28, 1996 in Japan. Moreover, the demand for evacuation by elevator cars has been growing especially after the WTC collapse on September 11, 2001. In this context, we developed an elevator evacuation model to simulate evacuation completion time by multiple elevator cars. Moreover, we conducted case studies with this model to examine merits and demerits of evacuation by elevator cars in consideration of the influence of smoke. Main parameters are vertical travel time and waiting time for elevator cars. As a result, we found that elevator evacuation might be more effective than stairways evacuation under certain conditions such as a 57-story high-rise building with 32 elevator cars and 2 stairways based on an existing high-rise building in Japan.

Statistical Analysis on the Reliability of Sprinkler Systems: Study on a Risk-Based Evacuation Safety Design Method

To evaluate the importance of fire protection systems objectively in evacuation safety planning of building fires, authors have proposed a methodology for selecting both design fire scenarios and design fire simultaneously for performance-based fire safety design according to acceptable evacuation risk in fire, which we call risk-based evacuation safety design method or R-B ESDM in abbreviated term. An important factor when using the R-B ESDM is to set the reliability of sprinkler systems. Although several studies exist on the reliability of sprinkler systems, there is no study that looks into the relations of design fire and design fire scenarios. In order to introduce the reliability of sprinkler systems to R-B ESDM, the data of the national fire reports have been statistically analyzed by classifying the fires in the sprinklered spaces into three patterns: “fires that sprinklers extinguished,” “fires that sprinklers suppressed,” and “fires that sprinklers failed to control.” The probabilities of the three patterns have been calculated by using the number of fires according to the burned area. As a result, if the burned area for effective suppression is defined as less than 4 m2, the reliability of effective sprinkler activation turns out to be approximately 83 %.

Fire Risk-Based Evacuation Safety Derived from Statistical Analysis by Type of Building

The authors and their colleagues have been trying to construct a framework method of risk-based fire evacuation safety design for buildings. In the framework, it is necessary to determine a benchmark fire risk level to select design fires and scenarios appropriately. An attempt was made to develop this benchmark fire risk level by using 10 years of statistical data on residential fires. First, the acceptable evacuation risk for fire was established assuming that the level of evacuation risk for dwelling houses is the benchmark. Secondly, the fire statistics for buildings with different types of use was analyzed to establish a formula for the acceptable evacuation risk in the context of performance-based evacuation safety design that commonly holds for various types of use. Finally, there are discussions of other methods for determining the bench mark evacuation risk.