Roof Diaphragm Design Example

A roof design gives the chance to extra floor space in the roof volume similar to a space or upper room space.

Roof diaphragm design example.

Design the diaphragm for wind loading using allowable stress design method. The roof deck is supported by joists that are thick and spaced at 5 ft. Structures using wood frame shear walls or wood frame diaphragms to resist wind seismic or other lateral loads shall be designed and constructed in accordance with af pa sdpws and the applicable provisions of sections 2305 2306 and 2307. The manual includes pertinent design information considerations fastener information deck shear capacity tables and a plethora of highly relevant design examples stepping you through all the.

Main features roof diaphragm design example. Shear nailing of the roof diaphragm north south the diaphragm loaded in the north south direction has been selected to illustrate the design of a wood structural panel roof diaphragm. The sdi diaphragm design manual third edition is an excellent design reference every engineer should utilize if designing with steel deck diaphragms. A line load reaction of this pressure is distributed to the top of the wall at the roof plane via the vertical spanning capacity of the cladding over height h.

This horizontal element is known as the diaphragm. 13 5 l x 16 9 x l 13 5 18 ft 16 9 6 ft 24 14 4 psf. Design example 2 n flexible diaphragm design diaphragm unit shear at the east side of line 3 and at line 9 is 136 000 160 850. The roof acting as a simple span horizontal girder of depth b distributes the wind line load as a shear reaction along the top of the end walls perpendicular to l.

Figure 1 illustrates the basic concept for a roof and wall diaphragm. Design a roof deck for a length of l 500 ft. The diaphragm resists the in plane loads by acting as a large horizontal beam spanning between the supporting end walls that are known as shear walls. The roof diaphragm will take load from half the wall below and load directly applied to the diaphragm.

Now let s work on an example. At the roof level these wall reactions turn the load in the roof system in the plane of the roof. Lbs ft plf 2. Calculate the lateral load on the roof diaphragm.

The roof deck is a wr wide rib type panel with a panel width of 36. In figure 1 wind pressure on the walls parallel to length l act on the building. And a width b 300 ft. Section 2305 general design requirements for lateral force resisting systems 2305 1 general.

A similar design is required in the other orthogonal direction east west.