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                                          BUILDING CODES, LOADS, AND FIRE PROTECTION*


                   4.38  CHAPTER FOUR






































                                      FIGURE 4.9  Mineral fiber spray applied to (a) steel beam; (b) beam-and-girder floor system,
                                      with steel floor deck supporting a concrete slab.

                               primers are not generally required for corrosion protection when structural steel will be enclosed within
                               a building or otherwise protected from the elements.) If paint is specified for structural steel that will
                               subsequently be protected with spray-applied materials, the specifier should contact the paint and fire-
                               protection material suppliers in advance to ensure that the two materials are compatible. Otherwise, use
                               of expanded metal lath as supplementary mechanical bond may be required to ensure adequate adhesion.
                               Suspended Ceiling Systems.  A wide variety of proprietary suspended ceiling systems are also
                               available for protecting floors and beams and girders (Fig. 4.10). Fire-resistance ratings for such sys-
                               tems are published by Underwriters Laboratories. These systems are specifically designed for mem-
                               brane fire protection and require careful integration of ceiling tile, grid, and suspension systems.
                               Also, openings for light fixtures, air diffusers, and similar accessories must be adequately limited and
                               protected. As a consequence, manufacturer’s installation instructions should be closely followed.
                                 In the case of load-transfer trusses or girders that support loads from more than one floor, build-
                               ing codes may require individual member protection. As a consequence, suspended ceiling systems
                               may not be permitted for this application.

                               Concrete and Masonry.  Concrete, once widely used for fire protecting structural steel, is not par-
                               ticularly efficient for this application because of its weight and relatively high thermal conductivity.
                               As a result, concrete is now rarely used for fire protection only.
                                 Concrete floor slabs are common as fire protection for the tops of flexural members. Concrete or
                               masonry is also sometimes used to encase steel columns for architectural or structural purposes or
                               when more substantial resistance to abrasion and physical damage is required (Fig. 4.11).


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