Steel beam to reinforced concrete column/beam connection!

[alberto]

Hello to all!!!!

How do you calculate these type of connections? Are there any Eurocode provisions about them?

[AndyBeeton]

There are clauses in EC2 concerning bearing stress of steel (or other materials) on the concrete but not much else. There are however other published guidelines that aren't code specific, much of which concerns precast construction but there are useful parallel principals with steel-to-concrete. If your connection is moment resisting, it becomes a bit like a moment base plate turned through 90°.

[alberto]

Ok! If my connections is simply supported can I design it as an ordinary simply supported connection ignoring the concrete?

[rigid_joint]

Eurocodes say nothing directly for these cases but this is a quite common situation. In general, this type of connection makes sense for pinned supports.

You can design a fixed support but It' s very difficult to satisfy the criteria.

Also for these cases in real life, a fixed support is most probable to turn to a pinned through the years.

Where does your steel beam end? Over the rc column or at its edgeways?

If it's over, things are simple. Check anchorages for shear and pullout failure.

If it's at the edgeways, checks depend more on parameters like: column section dimensions, stirrups distances, cracking and so on.

Anchorage checks are in ETAG guidelines of the European Organization for Technical Approvals.

Steel beam to concrete column/beam connection!

The title is wrong. Steel beam to reinforced concrete column you mean.

[alberto]

The title is wrong. Steel beam to reinforced concrete column you mean.

Yes of course. I hope the admins will correct it.

The steel beams are supported by steel columns and a reinforced concrete beam.
I will simulate the connection as pinned. Do I have to check the pullout failure? I am asking because there is no moment and therefore no tensile force at the bolts of the connection.

[rigid_joint]

By your first post I understood something different, that a steel beam is supported by rc column.

Anyway, checks still remain the same. Were does this steal beam ends? Over rc beam or edgeways?

If it's edgeways, the checks are more difficult to be satisfied because the cracking parameter is critical. Also, beams usually have a relative small width e.g. 25cm and this circumscription affects on anchorage length limit.

Do i have to check the pullout failure?

In general the answer is still yes due to 2nd order effect moments.

Have also in mind that, in the edgeways case, due to 2nd order effects , there is also a torsional distress on rc beam. Is it critical? I don't know, depends on 2nd order effect values.

A sketch is necessary to understand more.

[AndyBeeton]

I just saw your correction above but I'll post this anyway then have another look...

It’s difficult to be specific if we don’t know what kind of connection it is but, you can do all kinds of things.

You can bolt an end plate connection to a column, for example. The bolts can be embedded/drilled, such as resin anchors or mechanical anchors, or they can be through-bolts in sleeves and so on. It is possible to cast bolts or studs in but tolerance is a big issue – if you do this, you would typically use a template and incorporate some tolerance in the steel fittings.

You can also cast inserts into the concrete and these can even be attached to the rebar, by welding for example.

You can bolt on brackets, cleats or fin plates, in a similar way to the way you would with as steel stanchion – this may fit you scenario for a simple supported beam. You just need to make sure that the bolts are OK in shear and in tension (tension due to the eccentricity on the cleats or fin plate).

If you can land your beam on top, you just need to account for bearing and any bolt or anchor tensions into the end of the column. It is also possible to fit a steel ‘stool’ to the top of the column, either by bolting into it or by fixing to projecting and threaded reinforcement bars (again tolerance is an issue but can be overcome with oversize or slotted holes.

If using resin anchors, don’t forget about fire, and with other anchor bolts, edge distance and spacing.

You can assess the interaction of moments and forces between column and beam in the usual way, using stiffness based on the full section, on transformed section or cracked section according to the precision you need.

[alberto]

Actually I didn't mention anything about column...
The title is "Steel beam to concrete column/beam connection!" because I thought that the design procedure would be the same!

Anyway thanks a lot for your help! The width of the concrete beam is 30cm and unfortunately the beam ends edgeways .
I am thinking of using an end plate welded at the beam's cross section and then anchored to the r/c beam.

[AndyBeeton]

I'm confused as I can't visualize your connection.

You could have pull out forces without 2nd order effects - they might simply arise if your connection has a bracket component that has a reaction applied at some distance from the joint interface - just a simple eccentricity effect.

[alberto]

This is the connection!