huangyhg

i beam into shear wall connection
i am designing a cantilever beam which will be connected to a shear wall. my supervisor instructed me to use hilti bolts to anchor the i beam into the shear wall. how do i design this connection?
is there an easier way to anchor the i beam into the shear wall?
design the embed plate as a base plate. determine the required shear and tensile forces in each bolt and design the hilti anchors accordingly.
be sure to take spacing and edge distances into account. also, given that it is a cantilevered beam on an embed with epoxy anchors (no redundancy - this seems like a critical connection), be sure to check the creep characteristics of the epoxy and also consider using a higher factor of safety than hilti gives for their allowables (i blieve they us a f.s. of 4).
touching on what structuraleit brings up, some senior engineers have given me some advice on post-installed anchors that i believe is sound.
the capacity of these bolts is very dependent on proper installation. once you get out into the field you realize some contractors are much better than others. we typically design these bolts for a higher factor of safety- typically twice that stated in the hilti tables. this isn't cheap, but depending on the application could be a good idea.
frv-
i don't think it has been implemented yet, but hilti has been talking about "certifying" people to install these adhesive anchors because, as you stated, the capacities are so dependent upon proper installation.
the certification would be for an individual, not a company, and would follow that person (i.e. if that person left the company they would need to have someone else certified).
i certainly don't think that unqualified people will not be installing the adhesive anchors anymore, but it is a step in the right direction.
one thing to keep in mind here in the icbo eis reports for many of these anchors is that they are not supposed to be applied in a situation where shock or vibratory loads, to include seismic loads, are to be resisted. if that is the case, then another type of anchor or connection should be used.
i frequently use an embedded steel plate with nelson stud anchors welded to the back, with the finn plate for the steel beam being field welded to the emmbedded plate. the beam is then bolted to the finn plate, and the top and bottom flanges welded to the embedded plate. not quite as simple, but it avoids the vibratory load issue.
mike mccann
mmc engineering
an important note.
most chemical anchors do not stand up very well in elevated temperatures. if this connection needs to be fire rated then you need to find an anchor that still works at elevated temperatures (rare) or use a mechanical anchor.
the same thing applies to welding, all welding should be carried out before the chemical anchors are installed.
it is not clear from your post if the shear wall is existing or proposed, but if it has not been poured yet then an embedded plate would be much more appropriate.
structuraleit-
we had a guy from hilti come to our office to give us a presentation on their new adhesive system (a result of the investigation of the big dig tunnel liner collapse) and he mentioned the certification. however, i too am not about to start trusting contractors just yet.
i would not use epoxy anchors, i suggest using hilti tz or hda anchors.
certified installers for anchors is not a bad idea. i heard a story of a builder who was installing anchors and did not clean out the hole before injecting the epoxy, needless to say the anchor was not anchored and just pulled out (schoolboy error). the sudden pullout of an anchor can be just as devastating as a weld fracture.
studentcivil08,
resolve you moment into a push-pull and design the anchors for the resulting pullout force.
does your beam frame in-plane of the shear wall or onto the face of the wall. if your framing onto the face of the wall, be sure you follow your moment through the wall.
also consider what effects temperature and vibration may have on your connection as mentioned above.
through bolts with plates on both sides of wall eliminates the contracter certification debate. analyze the wall after the design of the plate/bolts for moment capacity.
has the shear wall been cast yet?
would prefer to embed weld plates into the wall to later weld to the canti beam. just be careful about expansion of the plate when welding (provide a gap around the edge of the plates).

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