Specification C1.11 Performance Of External Walls In Fire | NCC

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6. Specification C1.11 Performance of external walls in fire

Specification C1.11 Performance of external walls in fire

Specification C1.11 Performance of external walls in fire

1. Scope

This Specification contains measures to minimise, in the event of fire, the likelihood of external walls covered by Clause 2 collapsing outwards as complete panels and the likelihood of panels separating from supporting members.

Intent

To clarify that Specification C1.11 aims to minimise the risk, in a fire, of external walls collapsing outwards as complete panels and panels separating from supporting members.

Specification C1.11 contains detailed Deemed-to-Satisfy Provisions that could form part of a solution to achieve CP5. These provisions include solutions to avoid the potential collapse outwards, as whole panels, of concrete external walls in a building with a rise in storeys of not more than 2, and minimum design loads which panel connections must resist during a fire.

2. Application

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—

(a)

consist of either single or multiple panels attached by steel connections to lateral supporting members; and

(b)

depend on those connections to resist outward movement of the panels relative to the supporting members; and

(c)

have height to thickness ratio not greater than 50.

Intent

To clarify that Specification C1.11 applies only to buildings with a rise in storeys of 2 or less, where those buildings have concrete external walls that could collapse as complete panels.

Specification C1.11 applies only to buildings with a rise in storeys of 2 or less, where the external walls are constructed using tilt-up and precast concrete panels.

Figure Spec C1.11(1) and Spec C1.11(2) illustrate some of the types of construction covered by Specification C1.11.

Figure Spec C1.11(1) Typical non-loadbearing panels required to comply with Specification C1.11 (Panels may be full bay, multiple vertically or horizontally spanning) Figure Spec C1.11(2) Typical loadbearing panels required to comply with Specification C1.11

3. General requirements for external wall panels

(a)

Cast-in inserts and fixings must be anchored into the panel with welded bars or be fixed to the panel reinforcement.

(b)

Cast-in inserts for top connections and fixings acting together must be able to resist an ultimate load of two times the larger of the forces required to develop—

(i)

the ultimate bending moment capacity of the panel at its base; or

(ii)

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.

(c)

Top connections of the panel exposed to fire, such as clips and drilled-in inserts, acting together must be able to resist an ultimate load of six times the larger of the forces required to develop the moment specified in (b)(i) or (ii).

Note.

Note.

The increased forces specified by use of the multiplier of two or six in (b) and (c) above are to take account of the lower strength of the connections and members at the higher than ambient temperatures expected in a fire.

(d)

Lateral supporting members and their connections must be designed to resist the connection forces specified in (b) and (c) and in the case of an eaves tie member the force in the member must be determined assuming that it deforms in a manner compatible with the lateral displacement of the wall panels, and that it acts in tension only.

(e)

External wall panels that span vertically must have at least two upper connections per panel to the supporting member, except that where a number of panels are designed to act as one unit, (e.g. tongue and groove hollow-core panels), only two upper connections are required for each unit.

(f)

External wall panels that span horizontally between columns must have at least two connections at each column.

(g)

Connections providing lateral support to a panel must be designed to remain engaged to the supported panel both before and during a fire.

Intent

To provide general requirements for external wall panels which will minimise the risk of them collapsing in a fire and causing death and/or injury.

The concrete shear cone is the element of a panel that provides the bulk of the interconnection or fixing load capacity of the panel to the main structure. The aim of Clause 3(a) is to provide some attachment to the panel after the concrete shear cone has failed during a fire. See Figure Spec C1.11(3).

Figure Spec C1.11(3) Typical anchor bars for inserts

Clause 3(b) sets out the strength capacity required for top inserts or fixings so that the collapsing framework or roof structure will pull the panel inwards. See Figure Spec C1.11(4). The value for outward displacement of one tenth of the panel’s height is based on observations of deflections on buildings during a fire.

Figure Spec C1.11(4) Forces to pull panel inwards

Drilled-in inserts and clips will suffer a greater strength loss from exposure to fire than cast-in inserts. The difference between the factor of two given in Clause 3(b) and of six in Clause 3(c) is based on engineering principles.

The lateral supporting members referred to in Clause 3(d), for “tilt-up type buildings”, may be roof beams or trusses.

Where the wall panels are supported by eaves tie members, Clause 3(d) requires that calculation of the forces in the eaves tie take into account the geometry of the deformations of the eaves tie. Figure Spec C1.11(5) illustrates this requirement.

Figure Spec C1.11(5) Forces in eaves tie

When applying the provisions of Clause 3(e), panels used in a group have to be actually “designed to act as one unit”. It is not enough for the designer just to nominate the number of panels that are to act together.

While Specification C1.11 mostly applies to vertically spanning panels, Clause 3(f) addresses specific provisions applicable to horizontally spanning panels.

4. Additional requirements for vertically spanning external wall panels adjacent to columns

(a)

Where vertically spanning external wall panels are located adjacent to columns, connections to the panels must be located and/or detailed to minimise forces that may develop between the panels and columns arising from the restraint of differential displacement.

(b)

The requirements of (a) are satisfied by—

(i)

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—

(A)

the square of the connection height (m) divided by one hundred and twenty-five, when the connection height is less than 5 m; or

(B)

the connection height (m) divided by twenty-five, when the connection height (m) is greater than or equal to 5 m; or

(ii)

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).

Intent

To provide some additional requirements to enhance the safety of vertically spanning external wall panels which are adjacent to columns.

Observation of the effects of fires shows that during a fire:

• concrete panel walls tend to bow away from a fire;
• steel framework softens; and
• steel columns tend to deflect into the building.

These results create large forces on fixings of concrete wall panels to steel columns. Accordingly, Clause 4(a) requires that connections minimise the effect of such forces.

The provisions of Clause 4(b) provide two means of complying with Clause 4(a). However, they may not be the only means. Clause 4(a) is a performance criterion.

Clause 4(b) provides two strategies for the designer to adopt to minimise fire induced forces on the means used to fix vertically spanning concrete wall panels to steel columns.

If the supporting framework is a material other than steel, such as concrete or timber, the differential deflections assumed by Clause 4 will not occur, and the requirements of Clause 4(b)(i) and (ii) will be inappropriate.

Clause 4(b)(i) suggests a design of a fixing that will accommodate the expected differential displacement. Figure Spec C1.11(6) illustrates possible solutions to provide for the deflections. The magnitude of the differential deflection given in Clause 4(b)(i)(A) and (B) is based on observations of buildings under fire conditions.

The solution referred to in Clause 4(b)(ii) depends on fixing the concrete panel to the eaves tie member, and taking up the differential deflection in the eaves tie member. The distance this connection must be made away from the column is specified.

If this option is taken, the eaves tie member must be designed to comply with Clause 3(d).

Figure Spec C1.11(6) Typical fixing to accommodate differential deflection under fire

Table of Contents

• Contents and Introduction

  • Copyright and licence notice

  • Introduction to the National Construction Code (NCC)

  • Introduction to NCC Volume One

• Section A Governing Requirements

  • Section A Governing Requirements

  • Part A1 Interpreting the NCC

  • Part A2 Compliance with the NCC

  • Part A3 Application of the NCC in States and Territories

  • Part A4 NCC referenced documents
  • Part A5 Documentation of design and construction

  • Part A6 Building classification

  • Part A7 United buildings

• Section B Structure

  • Part B1 Structural provisions

  • Part B1 Structural provisions (DtS)

  • Specification B1.2 Design of buildings in cyclonic areas

• Section C Fire resistance

  • Section C Fire Resistance

  • Part C1 Fire resistance and stability

  • Part C2 Compartmentation and separation

  • Part C3 Protection of openings

  • Specification C1.1 Fire-resisting construction

  • Specification C1.8 Structural tests for lightweight construction

  • Specification C1.10 Fire hazard properties

  • Specification C1.11 Performance of external walls in fire

  • Specification C1.13 Cavity barriers for fire-protected timber

  • Specification C1.13a Fire-protected timber

  • Specification C2.5 Smoke-proof walls in health-care and residential care buildings

  • Specification C3.4 Fire doors, smoke doors, fire windows and shutters

  • Specification C3.15 Penetration of walls, floors and ceilings by services

• Section D Access and egress

  • Section D Access and Egress

  • Part D1 Provision for escape

  • Part D2 Construction of exits

  • Part D3 Access for people with a disability

  • Specification D1.12 Non-required stairways, ramps and escalators

  • Specification D3.6 Braille and tactile signs

  • Specification D3.10 Accessible water entry/exit for swimming pools

• Section E Services and equipment

  • Part E1 Fire fighting equipment

  • Part E1 Fire fighting equipment (DtS)

  • Specification E1.5 Fire sprinkler systems

  • Specification E1.5a Class 2 and 3 buildings not more than 25 m in effective height

  • Specification E1.8 Fire control centres

  • Part E2 Smoke hazard management (Performance Requirements)
  • Part E2 Smoke hazard management (Deemed-to-Satisfy Provisions)
  • Specification E2.2a Smoke detection and alarm systems
  • Specification E2.2b Smoke exhaust systems
  • Specification E2.2c Smoke-and-heat vents
  • Specification E2.2d Residential fire safety systems

  • Part E3 Lift installations

  • Part E3 Lift installations (DtS)

  • Specification E3.1 Lift installations

  • Part E4 Visibility in an emergency, exit signs and warning systems

  • Part E4 Visibility in an emergency, exit signs and warning systems (DtS)

  • Specification E4.8 Photoluminescent exit signs

• Section F Health and amenity

  • Part F1 Damp and weatherproofing

  • Part F1 Damp and weatherproofing (DtS)

  • Part F2 Sanitary and other facilities

  • Part F2 Sanitary and other facilities (DtS)

  • Specification F2.9 Accessible adult change facilities

  • Part F3 Room heights

  • Part F3 Room heights (DtS)
  • Part F4 Light and ventilation
  • Part F4 Light and ventilation (DtS)

  • Part F5 Sound transmission and insulation

  • Part F5 Sound transmission and insulation (DtS)
  • Specification F5.2 Sound insulation for building elements

  • Specification F5.5 Impact sound — Test of equivalence

  • Part F6 Condensation management

  • Part F6 Condensation management (DtS)

• Section G Ancillary provisions

  • Part G1 Minor structures and components

  • Part G1 Minor structures and components (DtS)

  • Part G2 Boilers, pressure vessels, heating appliances, fireplaces, chimneys and flues

  • Part G2 Boilers, pressure vessels, heating appliances, fireplaces, chimneys and flues (DtS)
  • Specification G2.2 Installation of boilers and pressure vessels

  • Part G3 Atrium construction

  • Specification G3.8 Fire and smoke control systems in buildings containing atriums

  • Part G4 Construction in alpine areas

  • Part G4 Construction in alpine areas (DtS)

  • Part G5 Construction in bushfire prone areas

  • Part G5 Construction in bushfire prone areas (DtS)

  • Part G6 Occupiable outdoor areas

• Section H Special use buildings

  • Part H1 Class 9b buildings

  • Part H2 Public transport buildings

  • Part H3 Farm buildings and farm sheds

  • Specification H1.3 Construction of proscenium walls

• Section I * * * * *

  • Part I1 *  *  *  *  *

  • Part I2 *  *  *  *  *

• Section J Energy efficiency

  • Section J Energy Efficiency

  • Specification JVa Additional requirements

  • Specification JVb Modelling parameters

  • Specification JVc Modelling profiles

  • Part J0 Energy efficiency

  • Part J1 Building fabric

  • Part J2 * * * * *

  • Part J3 Building sealing

  • Part J4 *  *  *  *  *

  • Part J5 Air-conditioning and ventilation systems
  • Part J6 Artificial lighting and power

  • Part J7 Heated water supply and swimming pool and spa pool plant

  • Part J8 Facilities for energy monitoring

  • Specification J1.2 Material properties
  • Specification J1.5a Calculation of U-Value and solar admittance
  • Specification J1.5b Spandrel panel thermal performance
  • Specification J1.6 Sub-floor thermal performance
  • Specification J6 Lighting and power control devices

• Schedule 1 State & Territory appendices

• Commonwealth of Australia

  • Footnote: Other legislation and policies affecting buildings

• Australian Capital Territory

  • ACT Appendix

  • Footnote: Other legislation affecting buildings

• New South Wales

  • Introduction

  • Section A Governing Requirements

  • Section C Fire resistance
  • Section D Access and egress
  • Section E Services and equipment

  • Section F Health and amenity

  • Section G Ancillary provisions
  • Section H Special use buildings
  • NSW Part H101 Entertainment venues other than temporary structures and drive-in theatres
  • NSW Part H102 Temporary structures

  • NSW Part H103 Drive-in theatres

  • NSW Section J Energy efficiency

  • NSW Subsection J(A) Energy efficiency — Class 2 building and Class 4 parts

  • NSW Part J(A)1 Building fabric

  • NSW Part J(A)2 Building sealing

  • NSW Part J(A)3 Air-Conditioning and ventilation systems

  • NSW Part J(A)4 Heated water supply

  • NSW Part J(A)5 Facilities for energy monitoring

  • NSW Subsection J(B) Energy efficiency — Class 3 and Class 5 to 9 buildings

  • Schedule 3 Definitions

  • Schedule 4 Referenced documents

  • Footnote: Other legislation affecting buildings

• Northern Territory

  • Introduction

  • Section B Structure

  • Section E Services and equipment

  • Section F Health and amenity

  • Section G Ancillary provisions

  • Section H Special use buildings

  • NT Part H101 *  *  *  *  *

  • NT Part H102 Premises to be used for activities involving skin penetration

  • NT Part H103 Mortuaries

  • Section J Energy efficiency

  • NT Schedule 4 Referenced documents

  • Footnote: Other legislation affecting buildings

• Queensland

  • Introduction

  • Section B Structure

  • Section G Ancillary provisions

  • Qld Part G5 Construction in bushfire prone areas

  • Section J Energy efficiency

  • Qld Schedule 4 Referenced documents

  • Footnote: Other legislation affecting buildings

• South Australia

  • Introduction

  • Section A Governing Requirements

  • Section B Structure

  • Section C Fire Resistance
  • Section D Access and egress
  • Section E Services and equipment
  • Section F Health and amenity
  • Section G Ancillary provisions
  • SA Part G7 Access for maintenance
  • SA Part G8 Miscellaneous provisions

  • SA Part H3 Farm buildings

  • Section J Energy efficiency

  • Schedule 3 Definitions

  • Schedule 4 Referenced documents

  • Footnote: Other legislation affecting buildings

• Tasmania

  • Introduction

  • Section D Access and egress

  • Section E Services and equipment

  • Section F Health and amenity

  • Section G Ancillary provisions

  • Tas Part G2 *  *  *  *  *

  • Section H Special use buildings

  • Tas Part H101 *  *  *  *  *

  • Tas Part H102 Food premises

  • Tas Part H103 Dining rooms and bar rooms

  • Tas Part H104 *  *  *  *  *

  • Tas Part H105 *  *  *  *  *

  • Tas Part H106 Meat premises

  • Tas Part H107 Farm dairy premises

  • Tas Part H108 Pharmacies

  • Tas Part H109 Health service establishments

  • Tas Part H110 *  *  *  *  *

  • Tas Part H111 *  *  *  *  *

  • Tas Part H112 Mortuaries

  • Tas Part H113 Foundries

  • Tas Part H114 Premises for manufacture or processing of glass reinforced plastics

  • Tas Part H115 Premises for production or processing of isocyanates

  • Tas Part H116 Premises for electro-plating, electro-polishing, anodising or etching

  • Tas Part H117 Premises for lead processing

  • Tas Part H118 *  *  *  *  *

  • Tas Part H119 *  *  *  *  *

  • Tas Part H120 *  *  *  *  *

  • Tas Part H121 *  *  *  *  *

  • Tas Part H122 Early childhood centres and school age care facilities

  • Tas Part H123 Temporary structures

  • Tas Part H124 Premises where work is undertaken on gas-fuelled vehicles

  • Schedule 3 Definitions

  • Schedule 4 Referenced documents

  • Footnote: Other legislation affecting buildings

• Victoria

  • Introduction

  • Section B Structure

  • Section C Fire resistance

  • Section D Access and egress

  • Section E Services and equipment

  • Section F Health and amenity

  • Section G Ancillary provisions

  • Section H Special use buildings

  • Schedule 3 Definitions

  • Schedule 4 Referenced documents

  • Footnote: Other legislation affecting buildings

• Western Australia

  • Introduction

  • Section H Special use buildings

  • WA Part H101 Public buildings

  • Schedule 3 Definitions

  • Footnote: Other legislation affecting buildings

• Schedule 2 Abbreviations and symbols

  • Schedule 2 Abbreviations and symbols

• Schedule 3 Definitions

  • Schedule 3 Definitions

• Schedule 4 Referenced documents

  • Schedule 4 Referenced documents

• Schedule 5 Fire-resistance of building elements

  • Schedule 5 Fire-resistance of building elements

  • Annexure To Table 1

• Schedule 6 Fire hazard properties

  • Schedule 6 Fire hazard properties

• Schedule 7 Fire Safety Verification Method

  • 1.0 Preface

  • 1.1 Purpose

  • 1.2 How to use this Verification Method

  • 1.3 Performance-based design

  • 1.4 Design scenarios: NCC Performance Requirements

  • 1.5 Fire modelling to determine ASET

  • 2.1 Design scenario (BE)

  • 2.2 Design scenario (UT)

  • 2.3 Design scenario (CS)

  • 2.4 Design scenario (SF)

  • 2.5 Design scenario (HS)

  • 2.6 Design scenario (VS)

  • 2.7 Design scenario (IS)

  • 2.8 Design scenario (FI)

  • 2.9 Design scenario (UF)

  • 2.10 Design scenario (CF)

  • 2.11 Design scenario (RC)

  • 2.12 Design Scenario (SS)

• History of adoption

  • History of adoption

• List of amendments

  • List of amendments—NCC 2019—Volume One Amendment 1