Description

A preliminary BRANZ study into the fire performance of hollowcore concrete floors suggests that conventional fire design requirements for precast floors may need to be reviewed.

Since 2006, many seismic requirements have been introduced to hollowcore floor practice, including a link slab between the hollowcore unit and the adjacent beam.

Following these changes, concerns have been raised about the fire adequacy of hollowcore floors.

Recently, BRANZ undertook a fire experiment on a precast hollowcore floor system as part of an investigation into the effect of the link slab on the fire performance of hollowcore floors. This is the result from one experiment, and further work will be carried out to explore these observations.

Scope

This article includes:

• Fire design of concrete floors
• BRANZ fire test of a hollowcore floor system
• Theoretical fire resistance ratings
• Premature hollowcore web failure
• What did we find?
  • Review fire rating test for floor systems
  • Negative impact from restraining elements
  • Issue with link slabs in hollowcore floors