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re: beam splice[Subject Prev][Subject Next][Thread Prev][Thread Next]
- To: <seaint(--nospam--at)seaint.org>
- Subject: re: beam splice
- From: "Andrew Kester, P.E." <akester(--nospam--at)cfl.rr.com>
- Date: Tue, 22 Jan 2008 13:47:33 -0500
This exact beam splice question was posed in Jan 08 Modern Steel Construction and their response can be found on www.modernsteel.com.
Everyone has made just about every other pro and con point, but the engineer from MSC stated it is very difficult to develop the full cross section in a butt welded splice due to the access holes that must be provided at the webs in order to place the backer plate and groove weld. They say often only the flange area will be assumed to carry the flexural resistance, but this confused me as I always thought in a moment connection this was the common assumption per AISC (T/C couple per the depth of the beam and moment).
Anyway, in this case I would ask the GC/Fab if they prefer the following options that will get you the SERVICE LOAD MOMENT that you need rather than the full moment capacity of the beam which is rarely needed:
-End moment plates, shop welded, field bolted
-Top bottom flange plates, bolted or field FILLET WELD (easier, cheaper, less inspection concerns), shear plate bolted at webs. Plates allow for some flexibility and you can just size their length and thickness for the SERVICE LOAD rather than match the flange thickness
-Shear plate web bolted, top and bottom complete pen groove weld (detail it as welding from the top access, they can do this all on the ground indoors before erecting
In October 07 MSC (no I don't work for them but have been doing lots of research on moment connections), they compare two east coast low seismic projects with different types of projects and conclude it is up to the contractor and erector in terms of what is easiest or most economical, and a lot of that has to do with weather when it comes to welding. Also, crane rental is very expensive so sometimes they prefer to get the steel up with bolted shear plate connections so they can cut the crane loose, then come back with loose flange plates and weld them. Bolting may not be as easy as you think because it requires more precise fit up to line up both web and flange bolt holes....
With your one beam indoors, none of these should matter too much. I would use your phone and let the GC/fab decide, as you can engineer any of these in 20 minutes using pre-qualified AISC connections and the tables.
Andrew Kester, P.E.
ADK Structural Engineering, PLLC
1510 E. Colonial Ave., Suite 301
Orlando, FL 32803
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