Roof Diaphragm Action

A diaphragm is a horizontal component that distributes lateral loads from wind or seismic activity to the shear walls or foundation of a structure.

Roof diaphragm action.

The elements marked with numbers corresponding to the behavior of the diaphragm in action due to the application of the lateral loads. Defining a roof diaphragm. Double diagonally sheathed lumber diaphragms shall be designed and constructed in accordance with af pa sdpws. Similar changes to 2306 3 for shear walls.

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. The maximum roof diaphragm moment m equals ww wl x l2 8. This stiffness provides stability and replaces the need for other bracing elements. Diaphragms are a roof floor or other system transferring lateral forces applied to a building to the vertical elements such as the shear walls.

The diaphragm forces tend to be transferred to the vertical resisting elements. Roof diaphragm action roof diaphragm action amirzamanian structural op 23 jan 06 13 25. 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. A roof diaphragm can be constructed of steel plywood or concrete to create the rectangular plane underlying the roof panels.

The corresponding diaphragm chord forces are therefore equal to m divided by the diaphragm depth b. 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. Diaphragm actions in a roof a typical horizontal diaphragm can have an allowable shear value.

Gypsum board diaphragm ceilings shall be in accordance with section 2508 5. By which states as follows. 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. 2306 2 3 double diagonally sheathed lumber diaphragms.

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. The maximum unit shear on the wall diaphragm is also equal to the roof reaction r divided by b.