Experimental And Modeling Study Of Pedestrian Evacuation In Building Stairwell

The development of high-rise buildings and public places such as theaters, stadiums and tourist attractions suffer a rapid grow due to the fast increasing population. However, if emergencies such as fires occur, it is dangerous for pedestrians to escape from such kind of enclosures in which a huge crowd gathers. Therefore, it becomes a very hot research topic in recent years that how to evacuate pedestrians safely, effectively and fast. Furthermore, the issues concerning evacuation of pedestrians through building stairs are especially significant due to the structure characteristics of stairs.In this thesis, the characteristics of pedestrians movement and evacuation on building stairs were focused. The behavioral characteristics, congestion analysis, pedestrian flow and merging behavior were studied in detail. It is hopeful to provide suggestions and technical support for the optimal design of building stairs and crowd management in evacuations.Firstly, we performed observational experiments to capture the moving characteristics of pedestrians on building stairs. Pedestrians’ moving processes were recorded by digital cameras placed on front of the stairs and the basic parameters of pedestrian movement on stairs were analyzed and discussed. Referring to the observed data on the stairs of college campus, the manual counting method was adopted, and the multifactor analysis of variance and independent samples T tests were used to analyze the observed data. It was found that the stair, gender and grouping factors have significant effects on pedestrian’s walking speed and the effects of grouping are the most notable among the three factors, as well as the factors of grouping and gender have interactive effects on pedestrians’movement speeds. Referring to the observed data on the stairs of tourist attraction, pedestrians’arrival time interval distribution and speed distribution on different stairs were obtained and discussed; meanwhile, the fundamental diagrams were presented by using the proposed calculation method of pedestrians’ density and speed during certain time interval. It was found that the probabilities of arrival time interval decrease with the increase of the arrival time interval; meanwhile, the probability density functions of arrival time intervals for pedestrian movement downstairs and upstairs were obtained and analyzed. It was also found that for pedestrians on the stair regions of tourist attraction, the pedestrians’ arrival time interval is short and the pedestrians’ speed on stairs is low, which will cause the congestion of pedestrians on the stair regions. Two measures were proposed to reduce the risk of pedestrians on stair regions, including increase pedestrians’ arrival time intervals and increase pedestrians’ movement speeds on the stair regions. The fundamental diagrams obtained shown that for the five observed stair regions, the speed of pedestrians decrease with the increase of density in overall trend, but the influence is not significant.For the purpose of analyzing pedestrians’ evacuation characteristics on high-rise building stairs, the congestion characteristics on high-rise building stairs were discussed through the analysis of evacuation drills, the controlled experiments were performed to investigate pedestrians moving characteristics in phased evacuation and total evacuation; meanwhile, the movement characteristics of children on building stairs were also investigated. The evacuation drills conducted by National Institute of Standards and Technology were collected and analyzed. The evacuation efficiencies of the evacuation drills were analyzed and the proposed calculation procedures were also used to obtain the pedestrians’ densities and speeds during certain time interval. It was found that the higher occupancy rate in the stairs caused the higher flow rates in stairs, which indicated that the occupancy rate is a significant parameter in assessing the building flow rates on buildings stairs with different number of floors, evacuees and width of stairs. It was also found that the linear relationship between the mean flow rate and the occupancy rate, and with the decrease of the reciprocal of length of building stairs, the reciprocal of evacuation time decrease with approximate linear characteristics. Two evacuation experiments in a9-story high-rise building were conducted, which could represent the phased evacuation process and total evacuation process. The space-time distributions for participants, the speed of each participant walking through two adjacent floors and the specific flow for participants through different stair landings were presented and discussed. Meanwhile, the fundamental diagrams for the two experiments and comparison with empirical data were presented, and the influences of merging flow on pedestrian movement speed were also discussed. Results indicated that the process of merging flow influence pedestrians’ movement down stairs, and the detailed egress facilities and evacuation processes should be taken into account when the functions of SFPE Handbook are used to predict the evacuation variables.To investigate pedestrian flow on building stairs in detail, the pedestrian flow model based on crowd flow theory and merging flow model based on lattice gas model were proposed. The risk of high-rise building evacuation under emergency situation was analyzed and the macro features of pedestrians’ movement through building stairs were investigated by using the pedestrian flow model. Besides, an extended lattice gas model was proposed to investigate the merging flow process on the floor-stair interface of high-rise building, in which the parameters, such as the inner-side walking preference, the turning behavior and the different desired speeds between stair stream and floor stream were considered. The results indicated that the high strength of inner-side walking preference could boost the occurrence of the congestion in the case of the corridor adjacent to the incoming stair and the merging at floor-stair interface could retard the motion of pedestrians on incoming stair and reduce the moving speeds in the case of corridor adjacent to the incoming stair.Finally, we summarized this study and presented the main conclusions, meanwhile, the further research aspects based on this work was pointed out.