huangyhg

masonry bearing wall, supporting steel beam, joist, post...
what is the typical connection "style" for attaching a steel beam, steel open web joist, steel posts, etc... to a masonry bearing wall.
i was under the impression it typically involving a bearing plate bolted or welded to the "to be supported" member and then that plate being bolted to the wall via anchor rods, expansion bolts, etc... recently, an technique was brought to my attention of embedding a steel plate into the wall and the bottom of steel elevation and the beam/joist/post could be welded directly to that plate.
also, if the wall is not fully grouted, should a bond beam be used at the top course (directly beneath bearing elevation) and/or fill the top 3 courses of block solid to help distribute loads?
obviously i am a novice with masonry design...
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i usually embed a plate (contractor to shim, etc. at the time of installment and then weld the owsj or the beam to it with a couple of inches of 3/16 fillet weld or as reqd. either use strap anchors or headed studs...
dik
i also usually use an plate with headed studs set into grouted cells of the cmu at the time of wall construction/grouting, and then the beam or joist is welded to the plate when it is erected.
the contractors seem to preferr this as it is easier to shim and level up the plate when it is just the plate, than when the plate is attached to the beam, and you you have to fight the weight of the beam in the process of shimming/leveling.
you should have a bond beam with horizontal steel at the top course (bearing course) of the wall. this applies to both fully grouted or walls that have only selected cells reinforced and grouted.
this allows you to set the plate with studs without interrupting the construction process.
dick
do you provide an embedded plate at at the intervals of the joist or beams, or do you have a continuous plate for the full length of the wall? so, if joists are spaced at 4'oc, you could have, say, an 5"wide x 8" long plate at 4'oc?
if continous plate, how do you account for the discontinuity of the wall at this elevation, or if the plate is not the full width of the wall, you dont need to worry about it? this would be referring to mid-level floor joists with the wall continuing up to higher floors.
sorry so many questions...not too many references at my disposal.
try lookng at the masonry and steel detailing handbook by w. laska (paperback - jun 1, 1993) ...very useful, you can get it at amazon.com or others...
bkurgoeng... usually provide a bearing plate at ea beam, truss or joist... only time i use a continuous strap/angle if for securing roof deck.
dik
i also use a embed plate typically 6" wide x 9" long with headed studs. the plate is not continuous it is at each joist location (5 to 6 feet o.c.). in addition i specify a continuous masonry/conc. tie beam at the floor/roof joist elevation.
as far as floor joists, i would not use a continuous plate. typically a 5/8" plate roughly 8 or 9 inches long. even if the joists are spaced at 24" o.c.
if you have a floor joist application, depending on the elevation of the floor i sometimes specify a continuous angle bolted to the inside face of the masonry with stiffener plates every so often. then the floor joist is welded to the angle.
like planitarch recommended try getting a copy of the masonry and steel detailing handbook. it is a very good reference.
if the roof is lightweight (no ballast) and the uplift is significant, you may need dba's in lieu of headed studs. you might also need to lap the dba's with vertical rebar in grouted cores to engage some masonry to proide enough mass for holdown. don't forget to look at the load combination of 0.6d + w.
there was a building in lindsay, ontario that they replaced the roof three times before they decided to properly anchor the perimeter...
dik
with steel beams, you can bear the beam on the masonry or provide an embed plate on the face of the wall. either way, you should not weld the beam to the plate. when the beam expands or contracts, it will take the wall with it and crack the wall around the embed. i provide threaded studs welded to the plate and bolt those through the bottom flange in slotted holes. if the beam frames into the face of the wall, i provide slotted holes in the beam connection. for joists, i agree with what the others have posted.
you should have additional filled cells, a masonry column or a concrete column at all your point loads. you should have a bond beam at your diaphragm levels. these will function as providing something to hold embeds and diaphragm anchors. the steel in the bond beam can function as the chord reinforcing for your diaphragm as well as the flexural reinforcing as a beam when you have uplift.

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