8.15 - Diaphragm design
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SR structural roof decks provide a clean uncluttered soffit for the roofing system.
It is possible to enhance this uncluttered appearance by utilising the structural roof deck as a diaphragm to transfer wind loads from the perimeter walls to internal vertical bracing/walls, therefore reducing, or removing the need for in-plane roof bracing.
To design the deck as a diaphragm, the following must be considered:
- • Implications of deck layout, void sizes/locations and vertical bracing/wall positions.
- • Line loads applied to the diaphragm perimeter
- • Fixings to all perimeter edges of roof deck area
- • Minimum of three vertical bracing/braced wall locations required
Note: It is important to note that fixing type and frequency may need to be changed to enable diaphragm design - Refer to Fig.8.13a for recommended standard fixing configurations.
For useful guidance on stressed skin diaphragm design, refer to:
ECCS Publication No88: European Recommendations for the Application of Metal Sheeting acting as a Diaphragm
BS 5950-9: Structural use of steelwork in building – Code of practice for stressed skin design
SBI Document 174: Stabilisation by stressed skin diaphragm action
BS EN 1993-1-3: Cold-formed thin gauge members and sheeting, clause 10.3
Other items within 8.0 - Design - Roof deck:-
- 8.0 - Design - Roof deck
- 8.1 - Quality
- 8.2 - Spans
- 8.3 - Loads
- 8.4 - Standard end laps
- 8.5 - Extended end laps
- 8.6 - Raking supports and cutting
- 8.7 - Cantilevers
- 8.8 - Sheet lengths
- 8.9 - Fire rating
- 8.10 - Durability
- 8.11 - Acoustics
- 8.12 - Airtightness
- 8.13 - Fixing specification
- 8.14 - Non-fragility
- 8.15 - Diaphragm design
- 8.16 - Protex® warranted insulated system
- 8.17 - Aesthetics