composite beam with slab openings

[eajk1]

I am analyzing a steel beam designed as composite with shear studs. There is a large opening in the slab adjacent to the beam in the middle of the span. How does this affect the design of the beam as composite and how would it be analyzed?

 

[civilperson]

The width of the concrete flange at the hole is zero. No concrete, no composite. May need to place steel at the edge of the opening to replace the missing concrete, but the beam itself is only the section from the steel components. Check for flexure in the usual way, (non-composite for the the portion adjacent to the hole).

 

[dik]

I would treat the middle portion as a 'T' section and develop the composite shear on the beam from the opening to the reaction and put nominal connectors in the space where the hole is.

Dik

 

[miecz]

If you have concrete on one side of the beam, you are composite with that side. Different limits on effective width, though.

 

[csd72]

For deflection, your calcs would not need to be based on the smallest effective width but some sort of average.

What you choose for the deflection width depends on length of hole over span, location of hole e.t.c.

 

[lkjh345]

Agree with Jmiec.

Use the side away from the whole to the normal limits of effective width.

Use any concrete on the side with the hole that you can. Even if the edge of your hole is 1 foot from the centerline of your beam, the foot of concrete makes a difference.

FWIW: RAMSBEAM is very good and easy to use with composite sections.

 

[jike]

I agree with jmiec and lkjh345. With the opening on one side of beam the condition is similar to an edge beam or spandral beam where the composite beam has slab only on one side plus a small portion of slab from the center of the beam to the edge of the opening. Analyze it with this slab width and provide shear shear studs based upon that analysis.