Roof Diaphragm Openings

A diaphragm is a flat structural unit acting like a deep thin beam.

Roof diaphragm openings.

For shear look at the force acting on the net area. A gib plasterboard ceiling diaphragm is a stiff and strong horizontal element which will effectively transfer loads to connected bracing walls lines exceeding 6m or 7 5m with dragon ties to a maximum of 12m. It is strongly recommended that analysis for a diaphragm with an opening should be carried out. Diaphragm design with openings.

Gypsum board diaphragm ceilings shall be in accordance with section 2508 5. Using this basic concept the diaphragm shear forces can be determined and generally the same principles applied even with the introduction of roof openings or irregular building geometry. Openings in shear panels that materially effect their strength shall be fully detailed on the plans and shall have their edges adequately reinforced to transfer all shear stresses. Most openings of any significant size should be checked.

There are three large openings the aortic the esophageal and the caval opening plus a series of smaller ones. Double diagonally sheathed lumber diaphragms shall be designed and constructed in accordance with af pa sdpws. Wood diaphragm on reinforced cmu shearwalls neylon et al 2013. Roof chord continuity 4 5 1 4 openings at shear walls.

For a diaphragm with openings draw a free body diagram through it. Diaphragm openings immediately adjacent to the shear walls shall be less than 25 of the wall length for life safety and 15 of the wall length for immediate occupancy. A roof diaphragm shall be provided by attaching a minimum of 3 8 inch 9 5 mm wood structural panel which complies with section r803 to roof rafters or truss top chords in accordance with table r804 3 buildings with 3 1 or larger plan aspect ratio and with roof rafter slope pitch of 9 12 or larger shall have the roof rafters and ceiling joists blocked in accordance with figure r804 3 7 2. The in plane shear transfer demand at the wall shall be calculated.

A rectangular uninterrupted plane a diaphragm behaves primarily as if it were a short deep beam figure 1. Tier 2 evaluation procedure. 2306 2 4 gypsum board diaphragm ceilings. A diaphragm structure results when a series of such vertical and horizontal diaphragms are properly tied together to form a structural unit.

Except that two 3 m x 10 m openings are required in the diaphragm for architectural reasons the rest of the building is the same as in design example. 2306 2 3 double diagonally sheathed lumber diaphragms. The term diaphragm is usually applied to roofs and floors. In its most basic form i e.

A 20 m x 30 m building has a wood diaphragm on cmu walls as shown in figure 1. You ll probably need some kind of chord element around the opening to make sure the diaphragm isn t overstressed in bending. Similar changes to 2306 3 for shear walls.