Section factor and protection thickness assesment
Castellated and cellular beams
For castellated or cellular beams, or fabricated beams with holes, the thickness of the fire protection material should be 20% more than the thickness determined from the section factor of the original, uncut section for boards and sprays.
Effect of section dimensions
Fire resistance is expressed in units of time so one of the contributory factors to fire resistance is the heating rate of the member
Hot rolled H and I sections
When proprietary passive fire protection is necessary, the required thickness can be determined from manufacturer’s published data
Hot rolled unfilled hollow sections
For unfilled hollow sections, the required thickness of fire protection is also determined from values of section factor.
Traditional fire protection materials
For fire protection using concrete, blockwork and plasterboard, the best source of information on material thickness for specific fire resistance times is Guidelines for the Construction of Fire Resisting Structural Elements
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