How to Support Concrete Beam with an I-Beam?

[zakmuh]

Hello,

I have to design an extention for an existing structure. There are 3 columns with 2m centre-to-centre span. These coulmns support 200 x 400 beam, which supports another 200 x 300 secondary beam (supporting slabs). Contractor wants to knock down the middle column and keep the beams as they are, as the column stands right in the middle of the proposed master bedroom.
Can I use an I-beam (or a more suitable section), both ends connected to other beams and use steel plates and bolts to support existing beams??

Please check the attached sketch.

Many thanks in advance

 

[msquared48]

I assume you cannot add the beam below the existing concrete beam for head clearance reasons, so, rather than the using steel beam which would see a lot of torsion per your sketch and be difficult to attach, I would very strongly consider widening the existing concrete beam, perhaps making the extension a little deeper if possible.

Mike McCann
MMC Engineering

 

[msquared48]

As an additional comment, at only a 13 foot span, will the existing concrete edge beam work?

What do you know about the existing reinforcing, size, grade, and concrete strength?

Mike McCann
MMC Engineering

 

[zakmuh]

Hi Mike! Thanks for your comments

You're right. I can't add the I-beam below for head clearance reason. My sketch just illustrates my porposal.
Edge beams having heavy reinforcement, 6-T16 at the bottom and 3-T16 (Fy 460 N/mm^2) at top with 200 width and 400 depth for 4m (13ft) span. Concrete strength (Fck, cyl) from the test is 32 N/mm^2.

Can you please guide me (with a sketch,if possible)on widening the existing beam, I believe this will require close monitoring during site work?

 

[Guest262653]

Have you considered using a U section web-doweled to the concrete beam? That could eliminate the torsional load problem as the shear centre is outside the section and closer to the load application line. It is easier to install as well.

 

[BAretired]

I assume T16 is a 16mm deformed bar, correct? Check the capacity of the edge beam. If it is adequate, the middle column can be removed without further ado.

BA

 

[zakmuh]

Thank you.

 

[BAretired]

I know what the concern is. Check whether or not the edge beam is capable of carrying the secondary beam reaction without the middle column.


BA

 

[trainguy]

zakmuh,

Make sure that your edge beam checks include verifying that the existing bottom re-bars are adequately long and continuous at the new location of maximum positive moment.

Also, don't forget to check that the existing columns can handle the added load.

tg

 

[hokie66]

Nothing was said about stirrups. In addition to advice above, check the shear.