huangyhg

hollow core connections
i have a few questions regarding hollow core bearing details:
1. hollow core on wt beam - when you bear plank on the bottom flanges of a wt for an interior bearing condition - how do most of you fasten the plank to the beam? for a typical steel w-beam we will use a headed stud at 4' o.c., but this does not work for a wt. in the past we have used two options which have both been met with resistance:
embed plate in plank - we have found that several large plank manuf (such as coreslab) do not have the capability of placing embeds or weld plates in their precast planks.
flag bar welded to beam web - contractors think this method is way to time consuming and always ask for an alternative. (i complelety understand their frustrations)
also, do you require that alternate slabs (on each side of the web) be 'tied' together. this is usally done for a w-beam bearing detail when the beam web does not conflict with placing the bar. i've seen typical details that place a #4 bar similar over the top of the web and grout it in the keyway of each plank to tie the slabs together. this is very difficult to do when there is no (or very thin) topping. (see attached detail)
2. hollow core on light gage wall - we are seing more and more light gage/hollow core projects. does anyone have a good fastening detail? this has become especially difficult when an owner/arch wants to work with a plank manuf who doesn't have the capabilities to install embed plates. is there another good way to do this?
i've attached a few details for reference. if anyone has any input or manuf websites they could suggest with good details - please let me know.

i am not sure where you are located but look this company website
regarding your detail, i've used the #4 or 15m bars @ 4' bent over the st section in the grout space between the planks (may not work so well in a seismic area) and no weld plate on the bottom... a continuous 1/8" untempered masonite strip or korolath bearing strip.
dik
i would use the flag bars, or weld rebar to the wt. i had a plank manufacturer recommend we use flag bars over the welded rebar. perhaps that recommendation is just a difference in practice in our areas, since in your area it seems to be an issue. what alternate do you usually provide when they ask for something other than flag bars?
i think your precaster has to get into the 21st century! flexicore and spancrete can both cast-in weld plates which is the simple solution.
for steel stud bearing i've seen a 4x3-1/2 angle tac-welded to the steel studs at the top of the wall and then weld the cast-in precast weld plates to it.

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