Roof Diaphragm Action

2306 2 3 double diagonally sheathed lumber diaphragms.

Roof diaphragm action.

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. Roof diaphragm action roof diaphragm action amirzamanian structural op 23 jan 06 13 25. The maximum unit shear on the wall diaphragm is also equal to the roof reaction r divided by b. The elements marked with numbers corresponding to the behavior of the diaphragm in action due to the application of the lateral loads.

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. Let s take a hypothetical horizontal diaphragm in service under following conditions and examine the allowable shear values. 2306 2 4 gypsum board diaphragm ceilings. Similar changes to 2306 3 for shear walls.

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. The diaphragm forces tend to be transferred to the vertical resisting elements. 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. Gypsum board diaphragm ceilings shall be in accordance with section 2508 5.

Diaphragm actions in a roof a typical horizontal diaphragm can have an allowable shear value. 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. By which states as follows. Diaphragms are a roof floor or other system transferring lateral forces applied to a building to the vertical elements such as the shear walls.

This stiffness provides stability and replaces the need for other bracing elements. A roof diaphragm can be constructed of steel plywood or concrete to create the rectangular plane underlying the roof panels. The roof sheets alone cannot normally act as a shear diaphragm but the purlins and bracing in the plane of the roof normally act as a diaphragm. A diaphragm is a horizontal component that distributes lateral loads from wind or seismic activity to the shear walls or foundation of a structure.

Double diagonally sheathed lumber diaphragms shall be designed and constructed in accordance with af pa sdpws. Defining a roof diaphragm.