Side Corbel Baseplates

[planc]

In your experiences, how strong are corbel baseplates at the sides supporting an I-beam above it? Post installed anchors will be used (meaning there is already existing column/concrete).

See attached picture. The top baseplate where the I-beam frames into it has very insufficient anchoring, since the past contractor just put them before pour and another contractor just put the baseplate without adding post-installed anchors.

So one possiibility is to put corbel at the sides via a baseplate and anchors post installed. Questions.

1. Should the 2 plates be welded (top and sides)?
2. Assume the cone failure lines won't insect (between top and side anchors, we will design it that way). I'm just asking how strong are corbels baseplates generally in this message.

3. Please share what you actually did or seen. And some pictures or sketch. Thank you.

 

[KootK]

It's difficult to comment on how strong a thing is without some basis for comparison. I would say that a stiffened bracket such as you've shown will tend to be much weaker than the direct bearing provided by the column. For that reason, I'd be inclined to not use a stiffened bracket at all since that will tend to send all of the beam reaction out to the tip of the corbel. Unless you need to resist uplift loads, I would prefer something like the detail shown below which is designed to allow the beam reaction to remain substantially resisted by direct bearing upon the column.

Please share what you actually did or seen. And some pictures or sketch. Thank you.

For future reference, I suspect that statement is why you've not received a very timely, nor vigorous, response to your questions. It sets the bar too high. When posters here specifically request sketches, photos, or specific code references, that tends to dissuade the folks who don't have time for that kind of thing from responding at all. And most structural engineers don't have time for that kind of thing. It tends to feel like assigned homework. In my opinion, you'll get more traction by allowing the community to respond with text only responses if they wish and then, if you don't understand what they've written, politely request a sketch for clarification. Know that I mean for this advice to be helpful and not offensive. I guess we'll see how I did with that...

 

[planc]

Oh. Almost missed this important reply of yours.

The corbel won't be carrying much axial loads in the beam framing into it. Corbel will be added to resist lateral movement of the 9.8 feet (3 meter) high wall below it. See attached illustration of the lateral loading. It is in top storey. There is of course beam designed below to carry the wall but no concrete beam was put above. Instead it's an I-beam that is weakly anchored on top of the column. So the corbel or side plate will be to resist the wall lateral movement. Imagine the wall vertical rebars epoxied to the bottom concrete beam 4 inches deep with low viscosity epoxy and the top will either be welded at bottom of I-beam on top of wall or vertically inserted to hole in the flange of the I-beam on top.

Would a corbel work to make the wall resist lateral movement (with many cyclic loading)? Or must your red drawn plate design above must be used to resist the wall out of plane cyclic lateral loading (imagine the wall become like a slab sideways with full dead and live load bearing on the side so the top column anchors must be competent)? The existing top anchor bolt is so poor because contractor just inserted them without any consultation (imagine bolt so weak it won't engage the baseplate or the end of the bolt just yielding so let's ignore the top anchors, assume cone failure won't occur or overlap that of the side corbel plate). Thanks.

 

[KootK]

The corbel won't be carrying much axial loads in the beam framing into it.

I'm not sure that you'll be able to prevent axial load from migrating into the corbel once you install it.

Would a corbel work to make the wall resist lateral movement (with many cyclic loading)?

Probably if designed correctly. Is the wall attached to the top flange of the beam? Bottom flange? Web? I'd be a bit concerned for the eccentricity between the point of load delivery and the top of the bracket.

Would either of the alternate bracket options shown below work for you? To me, they both feel like more efficient load transfer paths.

 

[planc]

In the photo. The wall that you see is the other building wall. Client has no wall because he thought what would be use of own wall if the neighbor wall is just inches away. So he just cover it with a board. But I told him he needs own masonry or concrete wall. So imagine a wall rising up to meet the I-beam.

1. Do you suggest masonry or concrete wall?
2. Would it work if the concrete wall would have the vertical doweled just inserted into 4 inches deep drill at the existing concrete beam below (it is sized to support wall) with low viscosity epoxy put? Won't the epoxied dowel pull out in event of cyclic lateral loading?

3. How do you usually attached wall to I-beam. By welding the vertical rebars on the I-beam bottom? But is it not mere bending the bar would make the bend weak? I plan to drill hole in the I-beam where the rebar can be inserted (if it can be drilled because the flange is kind of thick). How do you usually connect them when you built masonry or concrete wall attached to I-beam above?

4. And most important. How do you strengthen the connection of the I-beam to the column via side baseplate? If you just connected it to the perpendicular I-beam (in your drawing) which is the metal roof rafter. It won't strengthen the main baseplate connection to the column. In lateral wall movement, the entire top would just move so imagine the existing baseplate just disconnecting from the column top. Right now. The anchors are just enough for the metal roof rafter. If we add a masonry or concrete wall. The wall top i-beam support to the column must be strengthened

5. So what is best additional side baseplate to strengthened the I-beam (the top support of the wall) to the column? Can you also weld the side baseplate to the existing top baseplate or must there be no welding. I'm thinking if you weld it, you could use the existing top baseplate as support for the I-beam since the I-beam rested on the top existing baseplate continuous to the other side with the rafter shown in the photo framing into it at center perpendicularly (see original zoom out picture in first message). Thanks.

 

[KootK]

1) I have no preference.

2) I don't see it working if you're suggesting a wall that is cantilevered from the concrete beam below.

3) For a non-bearing wall, I most commonly see intermittent keeper angles that weld to the beam and hold the block in place laterally.

If you just connected it to the perpendicular I-beam (in your drawing) which is the metal roof rafter. It won't strengthen the main baseplate connection to the column.

4) I'm confused by that. I would have thought that the perpendicular beam had to be connected to the column in order to laterally stabilize the top of the column. Is that not the case? Regardless, the lateral load of the new wall will ultimately have to get transferred into the roof deck. As such, a direct connection between your over wall beam and the beam running perpendicular to it should be suitable for that purpose.

5) I'd recommend the clip connection that I showed in my original post but on all three beams if none of them has a positive lateral connection to the column.

Can you also weld the side baseplate to the existing top baseplate or must there be no welding.

There can be welding and that may well be desirable is weld access isn't a problem.

 

[planc]

For 1. When you drop a concrete hollow block, is it supposed to break? I tried it and it broke into pieces. so imagine the wall having lateral movement, if the pieces break, won't the wall break apart even with vertical reinforcement. Some said though the vertical reinforcement act like mini column and the weakness of the hollow blocks have not much effect. What you think?

For 2. I only meant the vertical rebar would be dowel by drilling 4 inches deep concrete with epoxy AND welding the vertical dowel of wall at the flange of the I-beam. Of course only fixing it bottom won't work unless it's a retainer wall.

For 3. Is your word "intermittent keeper angles that weld to the beam" welded to the beam rebar inside so you have to chip the concrete covering of the beam at center? Won't this weaken the beam? But the beam uses grade 60 rebar so can't be welded. Even if it could. You will weld the rebar to an angle bar (what size for example)? can you please share picture of this angle bar welded to beam? Haven't seen anything like it before.

For 4. The perpendicular rafter I-beam was welded to the wall top continuous I-beam. It's easier that way than welding the rafter I-beam to the baseplate separate from the wall I-beam. But even in the latter case, since they are all welded together in the baseplate. It won't matter if the rafter was directly welded to the wall I-beam or they were separately welded to baseplate independent. Is it not? The reason the latter was not done was because the metal roof was sloped higher in the center down to the sides. So you can't just weld the rafter to the baseplate because it's not totally horizontal. That's why rafter was welded to I-beam. The problem with all cases of the base was the baseplate anchor. Not strong enough if the new wall will encounter lateral movement.

For 5. You mentioned "positive lateral connection". So it is possible for baseplate to have positive axial connection and not enough "positive lateral connection" (for example insuffucient anchors)? Is that what you meant? So many thanks KootK!

 

[KootK]

Some said though the vertical reinforcement act like mini column and the weakness of the hollow blocks have not much effect. What you think?

I have confidence in properly design and detailed masonry as a structural material.

Is your word "intermittent keeper angles that weld to the beam" welded to the beam rebar inside so you have to chip the concrete covering of the beam at center?

No, the angles that I'm envisioning would be welded to a steel beam, not a concrete one.

can you please share picture of this angle bar welded to beam?

I'm afraid not.

But even in the latter case, since they are all welded together in the baseplate. It won't matter if the rafter was directly welded to the wall I-beam or they were separately welded to baseplate independent. Is it not?

Sounds about right.

So it is possible for baseplate to have positive axial connection and not enough "positive lateral connection" (for example insuffucient anchors)?

That is possible.

Is that what you meant?

No. I simply meant that if no positive, lateral connection existed for any of the beams, then they should all receive a new, positive, lateral connection.

 

[planc]

So we will use your clip connection between ibeam snd column. notice that the ibeam spans 6 meters before support. for chb, you need another stiffiner column halfway to the 6 meters. but witn concrete wall..doesnt have to do it. My concern with concrete wall is that its very.heavy. a 2.8 meter high wall will have about 10 kN per beam lenght.of 1 meter..this is almost like.a.ton per beam meter. we cant use chb because remember this is the next bldg inches away so the masons cant put finishing on tne exterior.side.

so we may just use 4" concrete wall with 12mm rebar expoxy injection every 8 inches vertical and horizonal.

now the heart of the questions..must we put 4 bolts instead of just 2 in your clip connection. Ibeam w8x21 spans 6 meters between columns. During the strongest seismic you may encounter. What kinds of post installed anchor bolt size must you use and how many in your clip connectiom. Maybe a 16mm chemical anchor bolt will do..is 2 sufficient to resist lateral load of the say 4 inches concrete wall..pls see attachment. have you see it before with tubes to be inserted and break apart when the bolt is inserted in. Hilti is so expensive because you need the epoxy injection too. what kind of epoxy anchors have you used?.

 

[JLNJ]

Sounds like your client needs to hire a structural engineer to engineer him an independent wall so that you building stays standing when the neighbor decides to take his wall down. I mean, you wouldn't take power from the neighbors wiring just because it was convenient and nearby your water heater.

 

[planc]

My experiences are only in reinforced concrete and simple baseplate with anchor bolts placed inside it. I'm not good in retrofit. And my structural colleague friend told me to put corbel. Unaware the reaction would send all of the beam reaction out to the tip of the corbel.

This is why I'm asking for tips. My simple solution to client is to demolish the entire I-beam and roofing so as to put a new column beam to the concrete column.

We have been solving this for a year already. Other structural engineers just don't have idea as all their know is baseplate on top, not on side.

That's why I need tips from KootK about this.

 

[planc]

It's just that I have never seen a concrete slab where one side is supported in an I-beam connected by baseplate and anchor bolts to the other side just like this wall with I-beam on top connected with side baseplate to a column. In seismic, not only does the wall bounce up and down with half height going up the above, but sideways like a slab during lateral motion.

Ok I'd like to services of KootK for this particular design. Other Structural engineers I talked to always put the I-beam on top of column with anchor bolts in the desired positional. And so no change to use sideway plate except bad designs done by constructor.
well No liability and no contract needed for KootK. Just design and pay via Paypal. Deal?

 

[KootK]

I'm afraid that's not possible planc. I'm not licensed to practice in the Philippines and, therefore, cannot responsibly provide final design recommendations for works constructed there. If you're not in a position to finalize the details of this connection design yourself then I recommend engaging a local structural engineer to assist you in that effort.

 

[planc]

My structural designer friend was the one who suggested putting corbel. But he is not an expert. Once I corrected him on use of Etabs when he mistaken increased all dead loads by 2X multiplier.

We dont have school for structural and all civil engineers just learn on their own. None are experts in side mounted panels thats why Im seeking tips from international experts. We use 16mm anchors most of the time and just hearing how others mount their side panels. Hilti software use top anchors and their software cant incorporate side panels and moment interactions.