Replacing Concrete Corbel with a Steel Plate.

[Tinguindin]

Hello

I designed a corbel for a bridge crane, but now the architect came back and said that he needed additional clearance (from the floor to the bottom of the corbel). They do not want to raise the roof, nor lower the slab. Being that the case, I need to find another way to support my bridge crane. I was thinking of a thick steel plate embedded into my column and cantilevering out, has anyone done that before?

Thanks

 

[paddingtongreen]

What is the size and lift of the crane? What ballpark are we in.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[Tinguindin]

Thanks "paddingtongreen"

Capacity of the Crane: 20 tons
Span : 55'
Lifting Height: 26'-0"
Weight of Trolley: 3,800 lbs
Weight of Bridge : 21,540 lbs

At the end, I ended up using a concentrated load of 74 kips to my supporting plate, 8" away from the back of my column.

Thanks

 

[vandede427]

having a continuous steel piece stick out of the column sounds like a formwork issue. usual attachments for steel to concrete involve embed plates with headed studs where the plate is flush to the concrete face. then a support bracket welded to the plate. i've designed joist girder supports to tilt-up walls in the order of 40kips offset 6" from wall face.

i think it's doable, but i'm not convinced you're going to save much head room. sometimes it's ok for structural to drive some of the decisions in a building and a buildings with 50' bridge cranes seems like one to me.

 

[BAretired]

You should be able to reduce the depth of crane beam adjacent to the column so that the bottom of corbel is flush with the bottom of the beam. See double overhead crane in the following link:

http://www.abuscranes.co.uk/Product...ranes/Double-girder_overhead_travelling_crane

BA

 

[Teguci]

How about an upside down tee shape (crane girders rest on bottom of tee). The tee is welded to an embedded plate in the concrete with HAS's and bent rebar welded to the back of it.

 

[Tinguindin]

Here is a Section that shows the Crain Rail Beam seating on top of the corbel ( now trying to replace it with a 1.5" thick plate). Like Teguci said, it will be welded to an embedded plate in the concrete.


Thanks

 

[hokie66]

How is your proposed plate oriented? New means of supporting crane runways are always risky. Crane runway support details have proven defective many times over the years for various reasons. For that matter, a concrete corbel is not exactly a common detail for crane buildings.

 

[vandede427]

again, i think you should step back and think about this in terms of priority and importance.

is the primary purpose of this particular building/room to house a bridge crane? if so, then why is something like headroom at the top of a stair mezzanine governing one of the most important connections in the building?

 

[BAretired]

I have to agree with hokie66 and vandede427 that this is not the sort of connection you want to experiment with.

BA

 

[connectegr]

A similar detail is often used for crane runways with steel columns. Your condition is actually the first I have seen it with a concrete column. I believe someone else posted that typically steel connections to concrete are achieved with embeds. I would suggest an embed plate designed for the moment, shear, and the horizontal thrust of the crane and considering cracked concrete. The design of the welds and plate should also consider fatigue. The design of the embed may require a large plate which is also good for field adjustment of the vertical plate.

http://www.FerrellEngineering.com