Fire-Resistance Design of Mass Timber and Connections
The 2021 International Building Code (IBC) contains new requirements for minimum fire-resistance ratings for mass timber elements used in new construction Types IV-A, IV-B and IV-C, whether exposed wood (where permitted) or protected with noncombustible materials. Noncombustible protection for mass timber in Types IV-A and IV-B construction serves to provide a portion of the fire resistance of individual elements. A designer can calculate the fire-resistance rating of a protected wood element by adding the fire-resistance rating of the unprotected heavy timber member to protection provided by a noncombustible material applied to exposed wood. The IBC also requires connections of columns and other primary structural members to be protected with materials that have the required fire-resistance rating. New code provisions provide two options for demonstrating compliance with this requirement for connections in Types IV-A, IV-B and IV-C construction: a testing option and a calculation option. A calculation method will be presented.