Abstract
When a fire occures in a room of an after-war-typs reinforced concrete buildings having large windows, flames spurting from the windows of the burning room may easily break panes of the upstair windows and make the fire spread to the upstairs. The study on the minimum distance of the spandrel necessary to prevent such a fire-spread has already been reported. In this paper it is discussed how a concrete, projection attached horizontally to the window against rain and scnshine helps to prevent such a fire-spread. The main results obtained are as follows: (1) On account of this projection, at first flames spurt out far form the window, and then rise along the building just as they would do when the window has no projection. (2) The law of similarity on the trajectory of hot gas spurting from the window has been found in the case where the window has such a projection. (3) Temperature distribution (along its trajectory) of hot gas spurting from the window with this projection lies between those in the following two cases; one is the distribution in the case where there is no wall part nor projection above the window and the other is the one in the case where there is wall part but no projection. The law of similarity on the trajectory has also been found in this temperature distribution. (4) This projection is more effective in the case when the window is long side rectangular than in the other cases. (5) The distance of the spandrel necessary to prevent fire-spread to upstairs when such a projection is attached has been calculated on several examples, which has been compared with the one required when the window has no projection.
