Roof Diaphragm Bracing

Challenges of calculating shear.

Roof diaphragm bracing.

The diaphragm forces tend to be transferred to the vertical resisting elements. When designed correctly a roof diaphragm can reduce or eliminate the need for diagonal bracing. We decide to use steel angle 2l sections as horizontal bracing to withstand the large axial loads. Usually the floor system will be sufficient to act as a diaphragm without the need for additional steel bracing.

The distance from the exteriors vertical bracing are large around 300 ft we have a large axial load in the roof steel deck diaphragm the loads exceed the resistance of the connectors of the deck. Bringing it back to basics you need to understand bracing lines the imaginary lines running along and across the full length or width of the plan for a timber framed building. When a roof diaphragm has no openings or obstructions the calculations for shear are. See figure on the right.

In structural engineering a diaphragm is a structural element that transmits lateral loads to the vertical resisting elements of a structure such as shear walls or frames diaphragms are typically horizontal but can be sloped such as in a gable roof on a wood structure or concrete ramp in a parking garage. Roof type one roof brace per 50m2 of roof area see rule 8 for minimum requirements one roof brace per 25m2 of roof area see rule 8 for minimum requirements 1. Sheathed elements such as walls and a roof covere d with panels and tied together provide additional strength to the building. At roof level bracing often known as a wind girder may be required to carry the horizontal forces at the top of the columns if there is no diaphragm.

Because this sheathing material does not provide a diaphragm at the plane of the roof other means of bracing the roof against horizontal loads must usually be employed. Or installed as a structural ceiling diaphragm in accordance with section 13 nzs 3604 ecoply structural racing and eiling diaphragms as specified in section 3 0 of the ecoply specification installation guide are suitable for bracing components in houses and. The bracing described in this brochure covers both framed roofs and fully trussed roofs. We are designing a large commercial warehouse.

This stiffness provides stability and replaces the need for other bracing elements. Dormers porches do not require bracing. Roof planes less than 6m2 e g.