Roof Diaphragm Aspect Ratio

Size and shape of diaphragms shall be limited as set forth in table 2305 2 3.

Roof diaphragm aspect ratio.

Diaphragm aspect ratio is ok. Analyses were performed for both loads applied in the longitudinal and transverse directions i e. The maximum unit shear on the wall diaphragm is also equal to the roof reaction r divided by b. But i can t find any similar limit for metal deck.

Behavior of a case study all wood panelized roof diaphragm. The sdi diaphragm design manual third edition is an excellent design reference every engineer should utilize if designing with steel deck diaphragms. Diaphragm aspect ratios sdpws table 4 2 4 type maximum length width ratio for an 84 x 34 diaphragm the aspect ratio is 2 5 3. 2306 2 3 double diagonally sheathed lumber diaphragms.

Min 12 7 and l. The dimensions of the case study diaphragm were 192 ft x 96 ft. The maximum roof diaphragm moment m equals ww wl x l2 8. Jump to full code chapter.

3 amongst all the models only four storey building with 1 4 aspect ratio has flexibility ratio greater than 1 5 so it s. The corresponding diaphragm chord forces are therefore equal to m divided by the diaphragm depth b. Wood structural panel unblocked 3 1 wood structural panel blocked 4 1 single layer straight lumber sheathing 2 1 single layer diagonal lumber sheathing 3 1 double layer diagonal lumber. 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 intricate details and covering nearly any.

There is a discussion going between the engineers in my office about the acceptibility of a 4 3 1 roof diaphragm. 2305 2 3 diaphragm aspect ratios. Gypsum board diaphragm ceilings shall be in accordance with section 2508 5. Roof diaphragm aspect ratio table 3 16a1 l.

Rafter span horizontal projection 26 16 rafter spacing 24 16 eave overhang length lesser of 2 or rafter length 3 2 rake overhang length lesser of 2 or outlooker length 2 2 roof slope 1 5 12 12 7 12 roof diaphragms. 2 since flexibility ratio increases with increase in aspect ratio of building we can say that flexibility of diaphragm increases with increase in aspect ratio. I know for plywood diaphragms the codes limit it to 4 1 aspect ratio. 2010 building code of ny 23 wood 2305 general design requirements for lateral force resisting systems 2305 2 design of wood diaphragms 2305 2 3 diaphragm aspect ratios.

2306 2 4 gypsum board diaphragm ceilings. Similar changes to 2306 3 for shear walls. Roof systems 3 1 3 4 lumber rafters. Wood diaphragm chords aspect ratios hokie66 structural 2 jan 11 14 56 when it gets too complicated to brace at the roof level brace at the ceiling level.