Roof Diaphragm Action

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 diaphragm action. Diaphragm action is an additional capacity of the panel to transfer the lateral loads to the outside edges of the panel to the eave for roof panels and to the ground for wall panels. By which states as follows. Diaphragm actions in a roof a typical horizontal diaphragm can have an allowable shear value. The diaphragm forces tend to be transferred to the vertical resisting elements.

The maximum roof diaphragm moment m equals ww wl x l2 8. The elements marked with numbers corresponding to the behavior of the diaphragm in action due to the application of the lateral loads. Metal deck may also be used as lateral restraint to stabilise the beams against lateral torsional buckling during construction where the deck spans perpendicular to the beam and through diaphragm action to stabilise the building as a whole by transferring wind loads back to the walls or columns where designed by the structural engineer. For wood structures diaphragms are commonly constructed of wood structural panel wsp sheathing or decking applied to the upper face of regularly spaced floor or roof wood framing members such as joists trusses purlins or sub purlins.

Double diagonally sheathed lumber diaphragms shall be designed and constructed in accordance with af pa sdpws. The maximum unit shear on the wall diaphragm is also equal to the roof reaction r divided by b. Defining a roof diaphragm. This stiffness provides stability and replaces the need for other bracing elements.

The corresponding diaphragm chord forces are therefore equal to m divided by the diaphragm depth b. 2306 2 3 double diagonally sheathed lumber diaphragms. The transverse applied lateral load is carried to the roof and foundation by the wall which is assumed here to be a vertically spanning element. 2306 2 4 gypsum board diaphragm ceilings.

In normal domestic construction there are standard details and rules for bracing and purlins which ensure that there is sufficient diaphragm action so that calculations are not required. Roof diaphragm action roof diaphragm action amirzamanian structural op 23 jan 06 13 25. A roof diaphragm can be constructed of steel plywood or concrete to create the rectangular plane underlying the roof panels. Diaphragms are a roof floor or other system transferring lateral forces applied to a building to the vertical elements such as the shear walls.

A diaphragm is a horizontal component that distributes lateral loads from wind or seismic activity to the shear walls or foundation of a structure. Gypsum board diaphragm ceilings shall be in accordance with section 2508 5.