Fire Protection Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/2241
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Item MODELING SOIL RESPONSE TO INTENSE HEATING FROM TUNNEL FIRES(2006-12-12) Hu, Xianxu; Marshall, André; Goodings, Deborah; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study investigates the response of saturated soils to intense heating from tunnel fires by numerical simulation. A general purpose commercial CFD code, FLUENT and a special porous media code, TOUGH2, are used. The conservation equations for porous media in each program are discussed and the numerical models are established. Two-dimensional simulations for the saturated coarse sand and the saturated fine sand are conducted and the results are compared with experimental data. It was found that models for capillary effects and relative permeability are required to describe the experimentally observed behavior. Without considering them, FLUENT predicts an inconsistent dry-out vapor zone in the soil column. TOUGH2 which includes these models gives the same two-zone structure observed in experiments, namely a liquid zone on the top and a two-phase zone at the bottom. The TOUGH2 results provide insight into the experimentally observed transient phenomena and agree well with experimentally observed trends.Item Critical Behavior of Long Span Cellular Beams in Fire(2006-05-08) Rini, Darlene; Milke, James A.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This paper presents an investigation of the structural response of a long span cellular beam with varying section geometries while subject to various temperature-time curves. This type of beam is under investigation, in part, because of its increased use in long span building construction and its unique thermal response when protected with intumescent coatings; but more importantly, to provide an increased understanding into how these beams affect the surrounding structure in fire conditions. A nonlinear, finite element computational analysis of a steel-frame composite structure incorporating a long span cellular beam with a composite deck was examined to investigate local buckling behavior, midspan displacements, and connection forces of the long span cellular beam, and to compare the results with a similar I-shaped member with no web openings. This study appears to indicate that long span cellular beams exposed to fire experience two buckling events prior to undergoing large displacement behavior and catenary action. In addition, global and local response of these beams is largely controlled by local web stiffness particularly in pre-buckling behavior.Item Extreme Geotechnical Response to High Heat From Tunnel Fires(2004-12-03) yong, meng wah; Marshall, Andre W; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study investigates the effects of heating on the transient behavior of the geologic media surrounding the tunnel involved in a severe fire, which typically involve extreme temperature and prolonged duration. Currently, there is little research being done in this area. An analytical model has been developed to predict the temperature rise of dry soil in the experimental soil column configuration and there is good agreement between analytical and experimental results. In water-saturated soils, the onset of convection happens in soil of higher permeability and there is propagation of a saturation temperature front at the onset of boiling, with greater propagation speed as permeability increases. There is also significant increase (~500%) in the pore water pressure building up in finer-grained saturated soil. This project then examines how these thermal transport modes and the pore water pressure increase in the soil medium can affect the stability of the tunnel lining.