In addition a second test was conducted by ul using a

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up of one bay of this building. In addition, a second test was conducted by UL using a gas-fired furnace designed to simulate the spandrel girder configuration. Representative fire, flame and girder temperatures are illustrated in Figure 38. As clearly illustrated by the flame-shielded spandrel girder concept, the "standard" ASTM fire test is not rep- resentative of the exposure that would be experienced Figure 35. Tubular steel columns filled with water for fire resist- ance with temperature variation during exposure to fire. Illustration courtesy of the American Iron and Steel Institute, Fire Protection Through Modern Building Codes. Figure 34. Fire protected exterior steel column with exposed metal column covers. Illustration courtesy of the American Iron and Steel Institute, Fire Protection Through Modern Building Codes. Lateral Reinforcement for Concrete Steel Column Concrete
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PAGE 73 SYSTEMS by exterior columns and girders. Research has been conducted worldwide over the last two decades to bet- ter define the appropriate exposure for exterior struc- tural elements. A comprehensive design guide is avail- able from AISI ( Design Guide For Fire-Safe Structural Steel ). Interior Applications Each building code defines conditions (occupancy, area and height) when unprotected bare steel framing is permitted. If fire protection is required by the build- ing code, structural steel exposed in the interior of a building may be protected with intumescent paint as described above. In other cases, a requirement to fire protect may be minimized or eliminated by a fire-engi- neered solution described in a following section. Another method for fire protecting architecturally exposed columns for both interior and exterior appli- cations involves encasing the members in a concrete- based insulating material that is then protected by an exterior steel jacket. This method is illustrated in Figures 39 and 40. Figure 36. Schematic representation of a liquid-filled column fire protection system. Illustration courtesy of U.S. Steel, Influence of Fire on Exposed Exterior Steel. Figure 37. Fire-resistive flame shielding on spandrel girder. Illustration courtesy of U.S. Steel, Influence of Fire on Exposed Exterior Steel. Figure 38. Flame patterns and temperatures during two tests on the load-carrying steel plate girder. Illustration courtesy of U.S. Steel, Influence of Fire on Exposed Exterior Steel.
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SYSTEMS PAGE 74 RATIONAL FIRE DESIGN BASED ON FIRE ENGINEERING As explained previously, North American building code requirements for structural fire protection are currently prescriptive; they are based on "standard" fire tests that do not accurately replicate actual constructed conditions or realistic fire exposures. In many cases, real fires result in higher temperatures but for much shorter duration than assumed by the current codes. As indicated previously, Figure 27 shows the temperature/time curve for the ASTM E119 standard fire test with a constant fuel source as contrasted with time/temperature curves in realistic fire exposures with different fuel loads. In these realistic tests, one can clearly see the higher initial temperatures
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