It is IBC 2009 so it will be ASCE 7-05 wind. I have AISC 360-10 but I do not have a copy of ASCE 11 or IEBC-09 at the moment.
On Sun, Dec 11, 2011 at 11:34 PM, Harold Sprague <firstname.lastname@example.org> wrote:
I presume that you have already looked at the following references:
AISC 350-10 Appendix 5 "Evaluation of Existing Structures"
ASCE 11 "Guideline for Structural Condition Assessment of Existing Buildings"
IEBC - 09 (which will refer you to ASCE 7-05)
Whatever your starting point, the changes between the ASCE 7-05 and the ASCE 7-10 are significant for wind design.
The IEBC may or may not be adopted by the jurisdiction, but it provides a basis for establishing an indication of the state of the practice. You did not say (or I missed it) which IBC you were referencing. Since the IBC 2012 is not official yet, I presume that you are using the IBC 2009 which will reference the ASCE 7-05.
Regards, Harold Sprague
Date: Sun, 11 Dec 2011 17:58:18 -0500
Subject: Re: EXIST'G METAL BLDG-NO DRAWINGS
I haven't really started on the project yet. I will find as much info out as I can.I am figuring on exceeding the limit for new lateral force into an existing element per IBC's section on existing buildings and having to bring all those elements up to current code. At least in the longitudinal direction, maybe I can get out of checking under new wind for the transverse direction.WH
Sent from my iPhone
On Dec 11, 2011, at 10:14 AM, ad026 rpransom <email@example.com> wrote:Will,Sent from my iPhone
It always blows my mind that owners don't receive the metal building drawings from the GC/erector. Or, if they do, they don't keep any drawings.
I am sure that you have talked to the owner about history of the building (e.g. why the endwall was open, was it ordered that way, who erected it, manufacturer (!!!), what year was a permit issued, etc.). Photos taken during construction can be helpful. Frequently the original owner, GC and sub-contractors are a wealth of information, even if they don't know engineering details or have since retired (retirees and photos can be your best friends. Retirees WITH photos ... share some time and prepare to learn).
Open endwalls are occasionally designed to be part of a future extension and may be identical to the next interior frame. At site you may find part marks for the frames, purlins, girts and possibly even a manufacturer's order number (jackpot!) - check the outer face of the outer flanges if they are accessible. Older buildings will be marked in crayon, newer buildings will be faded "permanent" marker and recent ones may have barcode labels.
Did you check for drawings on file at the building authority? Frequently the manufactured building drawings are not there but you may find the architectural (showing 4 elevations, a plan and a note to "see pre-eng drawings") and foundation drawings.
If the building was designed to be open, this may save a lot of time since your uplift loads will be lower in the closed condition. With open endwalls, foundations are frequently designed and installed to be identical to interior frame foundations. If the endwall frame is the same as the next frame, this will probably be the case.
Look for obvious patterns of symmetry (e.g. if the opposite endwall is closed and has identical purlin progression - 14ga, 16ga, 16ga, etc - from the end bay to the braced bay). Added (strut) purlins, doubled purlins, etc. are easy markers.
Are the sidewall braces in the same bay as the roof braces?
Pay particular attention to the purlin/girt lap conditions and fastening at the frames. Some manufacturers use load path reinforcing details that may not be obvious (e.g. small reinforcing plates that extend bearing forces through more bolts in the cold formed members).
Your proposed endwall posts should be located to align with the brace/frame intersections. It may even be practical to throw in some independent struts from endwall to braced bay and not be concerned about the purlin rows.
The foundation condition can get messy. Aside from rebar being hidden, the lateral thrust from a rigid frame may be difficult to resolve if you don't recognize the designer's method. There may be cross-ties (what a waste) or piles (even the original owner or GC would remember these details). The anchor rods are probably not a concern if they were good enough for open conditions. Again, look for patterns, such as identical foundation dimensions at the adjacent frame.
Even if you have foundation drawings, obtain as-built dimensions to the extent possible by excavation, and possibly take a core - see if you hit rebar in an expected location AND to check the concrete. (Recent project: nothing as-built matched the available drawings. Fortunately, on the conservative side.)
I agree with David Topete - it may be more efficient to assume least case and reinforce at foundation rather than waste time and money with tests to reach the same conclusions.
You indicate that you are "planning on remodeling under current wind." Why? Does it make a difference? Mandatory (e.g. regulatory) or convenient (e.g. software compatibility)? Just curious.
sent from my 10yr old desktop Mac :-)
Subject: EXIST'G METAL BLDG-NO DRAWINGS
From: William Haynes <firstname.lastname@example.org>
I have a project about to start that I am not looking forward to already.
They want to close the ends of a metal building that I would expect to be
in the 20 year old range at least based on the pictures I have seen. I am
From: DT <email@example.com>
Assume minimal reinforcing of the footings. Modify the base connections for e=
poxy anchors and add concrete mass as needed for added uplift resistance. Th=
at be cheaper than doing X-ray ndt and destructive investigative demo to onl=
y confirm the minimal reinforcing in the footings.=20
Depending where your pemb is located, assume absolute minimums on everything=
. Good luck with that project.