Specification 8 Performance of external walls in fire
S8C1
Scope
2019: Spec C1.11: 1
This Specification contains measures to minimise, in the event of fire, the likelihood of external walls covered by S8C2 collapsing outwards as complete panels and the likelihood of panels separating from supporting members.
S8C2
Application
2019: Spec C1.11: 2
This Specification applies to buildings having a rise in storeys of not more than 2 with concrete external walls that could collapse as complete panels (e.g. tilt-up and precast concrete) which—
- consist of either single or multiple panels attached by steel connections to lateral supporting members; and
- depend on those connections to resist outward movement of the panels relative to the supporting members; and
- have height to thickness ratio not greater than 50.
S8C3
General requirements for external wall panels
2019: Spec C1.11: 3
- the ultimate bending moment capacity of the panel at its base; or
- the overturning moment at the base of the panel arising from an outwards lateral displacement at the top of the panel equal to one tenth of the panel height.
Notes
The increased forces specified by the multiplier of two or six in (2) and (3) above are to take account of the lower strength of the connections and members at the higher than ambient temperatures expected in a fire.
S8C4
Additional requirements for vertically spanning external wall panels adjacent to columns
2019: Spec C1.11: 4
- detailing the connections and/or the supporting member to sustain a relative outward displacement of (d) between the panels and columns at the connection height where d(m) is calculated as—
- the square of the connection height (m) divided by one hundred and twenty-five, when the connection height is less than 5 m; or
- the connection height (m) divided by twenty-five, when the connection height (m) is greater than or equal to 5 m; or
- in situations where an eaves tie member is used to provide lateral support to external wall panels, the tie member is connected to the panels no closer than a distance (s) from the column where s(m) is taken as one quarter of the panel height (m).