Need a book? Engineering books recommendations...
Re: steel deck diaphragms[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: seaint(--nospam--at)seaint.org
- Subject: Re: steel deck diaphragms
- From: "Martin W. Johnson" <MWJ(--nospam--at)eqe.com>
- Date: Mon, 20 Sep 1999 09:28:57 -0700
While it is true that metal diaphragms do not suffer from cross-grain tension problems, they still have to be able to transfer inertia forces from the walls into the diaphragms. Metal diaphragms have their own unique behavior in this regard, in that the deck behavior to tension/compression forces is different in each axis. In the axis perpendicular to the flutes (corrugations) of the deck, the deck offers essentially no resistance to tension/compression forces. Fortunately, the support joists tend to be spaced at 8 ft or less in this direction. In this direction, the joist anchorage to the wall should be designed to resist the entire wall inertial force as point load, with the deck providing no resistance. In the axis parallel to the flutes, the continuous metal sheet which is attached to the ledger with puddle welds or screws is very rigid in resistance to tension/compression forces. Against tension, the deck alone should provide sufficient resistance. However, against compression, deck sections which are relatively shallow (i.e., 1.5 inches) and which have a relatively long deck span, may have a relatively high L/r ratio. Thus, they may be susceptible to compression buckling due to the wall inertia forces. Thus, in this axis, in some instances some small compression struts may be necessary to transfer the compression forces into the diaphragm, in a manner essentially equal to the subdiaphragm concept. I generally check for this by treating the deck as a column to determine the permitted axial compression stress based on kL/r. regards, Martin.
- Prev by Subject: Re: Steel deck diaphragms
- Next by Subject: RE: steel deck diaphragms
- Previous by thread: Re: Steel deck diaphragms
- Next by thread: RE: steel deck diaphragms