Experimental and Modeling Study of Pedestrian Evacuation in Building Stairwell


Student thesis: Doctoral Thesis

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  • Feizhou HUO


Awarding Institution
Award date22 Jun 2015


The rapid increase in population has hastened the development of high-rise buildings and public venues such as theaters and stadiums. With these kinds of enclosures drawing huge crowds, they can pose a threat in cases of emergencies such as fires, during which the escape of pedestrians becomes dangerous. Thus, the safe, effective, and fast evacuation of pedestrians become a popular research topic in recent years. Given the physical characteristics of stairs, issues concerning the evacuation of pedestrians through building staircases are especially significant.
This thesis focused on the characteristics of pedestrian movement and evacuation through building stairs. Behavioral characteristics, congestion analysis, pedestrian flow, and merging behavior were studied in detail. Through this study, we aim to provide suggestions and technical support for the optimal design of building stairs and for crowd management during evacuations.
We performed observational experiments to identify the characteristics of pedestrian movement on building stairs. The movement processes of pedestrians were recorded by digital cameras placed in front of staircases. The basic parameters of such movements were analyzed and discussed. Referring to observed data on the stairs of a college campus, we adopted the manual counting method and used multifactor analysis of variance and independent samples T-tests to analyze the observed data. Of the pedestrians on the observed stairs, 92.9% moved with speeds ranging from 0.45 m/s to 0.95 m/s, only 5.7% moved faster than 0.95 m/s, and only 1.4% moved slower than 0.45 m/s. Meanwhile, the movement speeds of the pedestrians descending the stairs were distributed in a normal manner. We also found that the factors of stairs, gender, and grouping had significant effects on the walking speed of the pedestrians. Among these three factors, grouping had the most notable effect. Grouping and gender had interactive effects on pedestrian movement speeds. Meanwhile, referring to the observed data on the stairs of a tourist site, we obtained and discussed the distribution of pedestrian arrival time intervals and speeds on different stairs. Fundamental diagram were presented using the proposed calculation method for pedestrian density and speed during a certain time interval. We found that arrival time interval probabilities decreased with the increase in arrival time interval. Furthermore, we obtained and analyzed the probability density functions of the arrival time intervals for pedestrian movement during stair descent and ascent. We found that on the stair regions of the tourist site, the pedestrian arrival time interval was short, and pedestrian speed was low, thus causing pedestrian congestion on the stair regions. Two measures were proposed to reduce the risk of pedestrian congestion on stair regions. These measures included the increase of both pedestrian arrival time intervals and pedestrian movement speeds on the stair regions. The fundamental diagrams obtained indicated that for the five observed stair regions, pedestrian speeds decreased with the increase in density in the overall trend; however, this influence was insignificant.
In analyzing the characteristics of pedestrian evacuation through high-rise building stairs, we discussed the characteristics of congestion on such stairs through the analysis of evacuation drill data. Controlled experiments were performed to investigate the characteristics of pedestrian movement in a phased evacuation and in a total evacuation. The movement characteristics of children on building stairs were also investigated. Data on the evacuation drills conducted by the National Institute of Standards and Technology were collected and analyzed . The evacuation efficiencies of the evacuation drills were included in the analysis. The proposed calculation procedures were used to obtain the pedestrian densities and speeds during a certain time interval. We found that an increased stair occupancy rate caused increased flow rates on stairs, indicating that occupancy rate is a significant parameter in assessing the flow rates on the stairs of buildings of different numbers of floors, evacuees, and stair widths. Furthermore, we found that a linear relationship between mean flow rate and occupancy rate, and with the decrease in the reciprocal of stair length, the reciprocal of evacuation time decreased with approximately linear characteristics. From the analysis of congestion characteristics, we found that high levels of services occurred mostly from 100 s to 600 s and that this period is significant in the evacuation process. Two evacuation experiments, which could represent the phased evacuation and total evacuation processes, were conducted in a nine-story high-rise building. The space-time distributions for participants, the speed of each participant walking through two adjacent floors, and the specific flow of participants through different stair landings were presented and discussed. Fundamental diagrams for the two experiments and a comparison with empirical data were presented. The influences of merging flow on pedestrian movement speed were also discussed. Results indicated that the merging flow process influences pedestrian stair descent and that detailed egress facilities and evacuation processes should be considered when using the functions of the Society of Fire Protection Engineers Handbook for predicting evacuation variables.
For a detailed investigation of pedestrian flow on building stairs, a pedestrian flow model based on crowd flow theory and a merging flow model based on the lattice gas model were proposed. The risks in high-rise building emergency evacuations were analyzed, and the macro features of pedestrian movement through building stairs were investigated using the pedestrian flow model. An extended lattice gas model was proposed for investigating the merging flow process at the floor-stair interface of a high-rise building. In this model, parameters such as the inner-side walking preference, turning behavior, and different desired speeds for stair and floor streams were considered. Results indicated that a high inner-side walking preference could boost the occurrence of congestion in corridors adjacent to incoming stairs and that merging at a floor-stair interface could impede the motion of pedestrians on incoming stairs and reduce the moving speeds along the corridors adjacent to the incoming stairs.
Finally, we summarized this study and presented the main conclusions. Further research aspects based on this work were also presented.