Roof Wall Diaphragm

The roof and foundation support the vertically spanning wall and consequently pick up the developed horizontal reactions.

Roof wall diaphragm.

The term diaphragm is usually applied to roofs and floors. A shear wall however is a vertical cantilevered diaphragm. 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. Figure 1 illustrates the basic concept for a roof and wall diaphragm.

Use apa sheathing tables in x305 peter von buelow university of michigan tcaup slide 19 of 28. Learn more about the force transfer around openings ftao method of shear wall analysis including downloadable ftao design tools. Strength and stiffness of a diaphragm depends on the panel properties the span arrangements and the quality of the connections. The diaphragm forces tend to be transferred to the vertical resisting elements.

The basic shape of a ceiling diaphragm is square or rectangular 1 1 or 1 2. Diaphragm and shear wall example given. If a larger opening is unavoidable this must be in the middle 1 3rd of the diaphragm. 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.

2306 2 4 gypsum board diaphragm ceilings. This horizontal element is known as the diaphragm. In figure 1 wind pressure on the walls parallel to length l act on the building. Design roof diaphragm sheathing and shear walls on short side.

At the roof level these wall reactions turn the load in the roof system in the plane of the roof. This stiffness provides stability and replaces the need for other bracing elements. Because this building has one story assume that the seismic weight is concentrated at roof level. Gypsum board diaphragm ceilings shall be in accordance with section 2508 5.

Table 2304 6 of the 2006 ibc lists the minimum thickness of wall sheathing and. Protrusions are permitted but cut outs for walls or sky lights are not. Specifically the ibc irc wfcm and icc 600 provide prescriptive shear wall details and designs that may be applied when certain basic conditions are met. Similar changes to 2306 3 for shear walls.

Also assume the mass is evenly distributed over the entire roof. Double diagonally sheathed lumber diaphragms shall be designed and constructed in accordance with af pa sdpws. Constructed with adequate floor and roof diaphragms and shear walls. Assuming a flexible roof diaphragm determine the forces in walls a b c and d for north south loading.