Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

Re: URM - Parapet Bracing Question -Reply

[Subject Prev][Subject Next][Thread Prev][Thread Next]
If (when) the roof anchors are required, a good way to acheive such is to
surface mount a flat strap or angle on the roof sheathing perpendicular to the
parapet and use this as the connection for a diagonal brace also. This would of
course require roof work at these locations. This scheme places the braces for
parapets at approx.6 ft. I think another acceptable means to "capture" the
parapet is to run an angle over the outside edge and fasten this to the braces.
I think I've done this (with a sufficiently stiff top angle) where I've spaced
the braces at 10 to 11 ft (2x5'-4").

Barry Welliver

Dennis S. Wish wrote:

> Thanks Tim, at one time there was an allowance to exceed the 6'-0" spacing
> for concrete capped parapet. This must have died some years ago in place of
> the 6'-0" max spacing.
> Thanks again for the reply
>
> Dennis Wish PE
>
> |-----Original Message-----
> |From: Tim McCormick [mailto:TMCCORMI(--nospam--at)BAS.CI.LA.CA.US]
> |Sent: Friday, February 20, 1998 1:43 PM
> |To: seaoc(--nospam--at)seaoc.org
> |Subject: URM - Parapet Bracing Question -Reply
> |
> |
> |Dennis,
> |
> |My copy of 1994 UCBC Appendix 1 does not have the 10 foot rule for
> |parapets. Anchors are generally limited to 6 feet but this could be
> strictly
> |interpreted to mean only the diaphragm anchorage as written. The actual
> |language is given below. By the way, I get these quick code quotes off
> |my ICBO CODE EXPRESS CD  I think this is a great tool for quickly finding
> |code requirements from all of the uniform codes. Here's the section:
> |
> | A113.6 Parapets. Parapets and exterior wall appendages not
> |conforming to this chapter shall be removed, or stabilized or braced to
> |ensure that the parapets and appendages remain in their original position.
> |The maximum height of an unbraced unreinforced masonry parapet
> |above the lower of either the level of tension anchors or roof sheathing
> |shall not exceed the height-to-thickness ratio shown in Table A-1-F. If
> |the required parapet height exceeds this maximum height, a bracing
> |system designed for the forces determined in accordance with Chapter
> |16 of the Building Code shall support the top of the parapet. Parapet
> |corrective work must be performed in conjunction with the installation of
> |tension roof anchors. The minimum height of a parapet above any wall
> |anchor shall be 12 inches (305 mm).
> |EXCEPTION: If a reinforced concrete beam is provided at the top of the
> |wall, the minimum height above the wall anchor may be 6 inches .
> |
> |Literally, this means its up to the design but I have seen most URM
> |parapet braces spaced at six feet.
> |
> |Hop this helps,
> |
> |Tim McCormick, P.E.
> |City of Los Angeles
> |
> |
> |
>