Study On Decision Conditions Of Quasi-Safety Zone About Firefighting In Urban Integrated Transport Hub

With the development of transport, urban transportation improves continuously. The integrated transport hub has emerged in the major cities one after another to meet the needs of convergence between the various transportation and transferring passengers. In the needs of utility, the transfer hall in integrated transport hub is often designed to large space structures. In the actual project, such large space structure position is usually designed as Quasi-Security Zone, because it beyond the requirements about areas of fire district and distance of fire safety evacuation provided in the existing norms. At present, the fire safety of Quasi-Security Zone is mainly demonstrated through performance-based fire prevention method but no more uniform design criteria.In this paper, cube model of transfer hall which area was 10,000 square meters was taken as the research object. Two ways of natural ventilations—top opening and high-side window opening was discussed respectively, generally applicable decision conditions of Quasi-Security Zone are presented.With regard to transfer hall using top opening in integrated transport hub, different headroom, different ratios accounted for floor area and different adjacent distances of natural ventilations was considered compositely to observe the effects of smoke exhaust. By choosing headroom as 5m, 6m, 8m, 9m, 10m, top opening ratio accounted for floor area as 2%,4%,6%,8%,10%,12%,14%,16%,18%,20%, and adjacent central distances of natural ventilations as 10m,20m,30m,40m,50m,60m and 70m, the necessary fire scene model was established and simulated by use of software FDS. Then within thirty minutes the parameters of critical security scene close to insecurity ones were analyzed. By taking advantage of three-dimensional surface fitting method, the determine equation designing transfer hall of integrated transport hub with top opening as Quasi-Security Zone was proposed.Towards transfer hall using high-side window opening in integrated transport hub, different headroom, different ratios accounted for floor area and different height of high-side window was considered. based on setting the area of a single high-side window to be one square meters, five headroom—5m, 6m, 8m, 9m, 10m, and three opening forms and area ratios of high-side window—opening area ratio of 2% on one group of opposite sides, opening area ratio of 2% on two groups of opposite sides and opening area ratio of 4% on two groups of opposite sides were selected to study comparatively. In addition, how opening height of high-side window affects the effects of smoke exhaust was researched through setting series of opening heights of high-side windows corresponding to different headroom. The results show that headroom of buildings and ratio accounted for floor area are the main effects on the smoke exhaust, high-side windows at the edge of the wall have obvious advantage on smoke exhaust compared to other opening height, when the high-side windows are not at the edge of the wall, the best opening height of high-side windows is at about 50% of headroom, and the best opening height is only related with headroom but the opening form and ratio accounted for floor area. If the transfer hall with high-side window openings is designed as Quasi-Security Zone, the high-side window opening area ratio accounted for floor area is not less than 4 percent when the headroom is lower than eight meters and 2 percent when higher than eight meters, and the high-side window should be continuous arranged at the edge of the wall when the headroom is lower than ten meters.