Roof Diaphragm Chord

At the roof level these wall reactions turn the load in the roof system in the plane of the roof.

Roof diaphragm chord.

Roof diaphragm chord for the diaphragm the chords carry the moment couple and the panels carry the web shear tension generally controls. The diaphragm chord can be a line of edge beams that is connected to the floor or reinforcing in the edge of a slab or in a spandrel. Curved diaphragms idealize it as flat. My chord force for the diaphragm is 4 2 kips.

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. The corresponding diaphragm chord forces are therefore equal to m divided by the diaphragm depth b. Unblocked diaphragm capacity capacities in sdpws are nominal values. The roof and foundation support the vertically spanning wall and consequently pick up the developed horizontal reactions.

The picture i see is a flanged beam with a large buckle in the middle and i have difficulty expecting that this condition can replace a flat horizontal diaphragm provided by sheeting the underside. The diaphragm forces tend to be transferred to the vertical resisting elements. Diaphragm openings immediately adjacent to the. Chord reinforcement must be provided in addition to any other required reinforcement such as flexural reinforcement.

In the case of roof and floor systems without perimeter beams the chord reinforcing bars are typically concentrated near the edge of the slab and are tied to either the top or bottom flexural reinforcement. Offset roof planes offset roof planes treat as two separate diaphragms each with. Not asd divide nominal values by 2 0 for asd capacity. The maximum unit shear on the wall diaphragm is also equal to the roof reaction r divided by b.

How does a sloped sheeted roof roof trusses 4 12 relate to the classic diaphragm modle which is presented as horizontal beam with roof edges acting as chords and the sheeting acting as the web. I designed the metal deck roof deck diaphragm and it can tranfer the lateral loads to the shear walls on each end. This horizontal element is known as the diaphragm. Examples of chords are shown in figure 4 28.

Idealizing and simplifying complicated structures. However the wall diaphragm moment equals r x h. Roof chord continuity 4 5 1 4 openings at shear walls. Chords are usually the double top plates of the walls but for simple but jointed members only 1 member is acting at the joint.

I am using the steel roof beam at the perimeter of the building to act as the chord member. Diaphragm sheathing floor roof framing parallel to walls add blocking floor joist blocking.