Composite Beam Design 1

[Calif]

Good Afternoon everyone:

Whats the quickest way to design composite steel beams? I am doing hand calculations and it is taking a while to do just one. Is there a free software anywhere to experdite this process? Any help would be appreciated.

Thank You

Kmat

 

[whyun]

For me, the most comprehensive software for composite steel beam design is RAMSBeam from

http://www.ramint.com

I've also seen a composite beam design module in Enercalc but my personal preference is RAMSBeam.

 

[Calif]

I am using an excel spreadsheet to speed up the process of designing composite beams. I have thought about something concerning composite action when beams are connected to a girder. When beams are connected, the girder picks up the supporting load of the beams acting in composite. The question is, since the beams are acting in composite and the girder is picking up there load, should the girder be analyzed as composite? The width of concrete (b) stipulated by AISC would be less than center to center spacing and 1/8 of each side of a girder in my mind. This is for internal girders. Can the width of an internal girder exceed into the supporting beam acting in composite? Does this make some since to anyone? A response would be appreciated.

Thanks

Kmat

 

[dik]

I've designed the supporting girders as composite also...

Dik

 

[Calif]

But how are you determing the width for a slab on the girder that is picking up point loads from supporting floor beams?

Peace

Kmat

 

[dik]

CSA S16.1 has requirements for the deck and slab thickness...

The effective slab thickness is the lesser of .25*span, 16*the slab thickness + width of the beam, and 1/2 the span to the adjacent beam for beams with slabs on both sides.

There are also requirements for slab and deck and steel studs often requiring that the composite deck be used in an inverted manner to achieve sufficient concrete for studs.

As far as the point loads, there are requirements for distributing the shear connectors along the beam to roughly correspond to the shear force diagram. It is possible, for example, to have a composite beam with a single large point load, say, at third span.

Dik

 

[Calif]

You are missing my question. How do you account for the slab width for a girder picking up beams? They cant just have those standard stated above in your post because that width will interfere with the supported beams connected to it. The slab width for a girder must be less than standards stated above.

Kmat

 

[dik]

For a slab on both sides of the girder, the width considered is the width of the beam plus 16 times the slab thickness. Shear studs are shop applied on the girder and the deck is tacked to either side. Elevation top of purlins is the same as elev top of girder and the deck sits on both with the shear studs for the purlins field applied through the deck.

Why would the manner of determining the slab with for the girder be less than that for the purlins as long as the shear can be transferred to the slab either through the stud or through the slab? There is also a requirement for providing trnasverse rfg. CSA requires 0.5% of the effective concrete area and the deck ribs provide stability. Consider it is a steel beam with a concrete T beam secured to the top where the stem of the T is only a matter of a few inches high. If this doesn't explain it, I may be missing your question completely...

Dik

 

[dik]

Forgot to add that the transverse reinf is to reduce splitting at the shear connectors and the concrete area is usually sufficient to transfer the compression.

Dik

 

[Calif]

I think you answered it but I have another question. What is CSA? Is it Canadian Standards Association? Did they develop the design standards for composite action beams?

Thanks

Kmat

 

[dik]

Part 17 of CSA S16.1 covers composite beams and columns and CSA is Canadian Standards Assoc. The National Research Council was fairly actively involved with composite construction a couple of decades back including OWSJ... The design committee also has a number of 'heavyweights' on it.

For the most part the composite design mimics a limit states approach and is fairly straight forward. I used to have programs for the old TI-59 (I think that's the model) as well as the old HP??. I've not had the need to write one for the TI-89 that I currently use...

Dik

 

[Calif]

What reference book are you using to site the sections for guide lines in the design for composite beam and column design?

Kmat

 

[dik]

Reference books? Common formulae are developed using limit states design for concrete and steel... not much else to it! As far as effective width of slab, I think the values selected are pretty conservative compared to any literature I've encountered. I cannot cite these, but I've not encountered literature to the contrary...

Dik

 

[Calif]

Where did you get, "Part 17 of CSA S16" from? I have not heard of CSA until you spoke of it. It is for my own curiousity.

Calif

 

[whyun]

Check out the design guides at AISC website. Design Guide 2 is "Design of Steel and Composite Beams with Web Openings".

Even one beam design can take longer than a few hours by hand. I have no affiliation with RAM International but for me, RAMSBeam is the best program for simple composite beam design.

 

[dik]

In Canada, most documents referenced by the National Building Code are CSA documents... they have several hundred (thousand?) of these covering almost anything including window, playground equipment. Our CSA 23.1-4 covers concrete similar to ACI, our S16 covers Limit States Design of Steel, our S136 covers Cold Formed Steel for North America (endorsed by AISI and Mexico) and so forth...

Dik

 

[Calif]

Whats the minimum thickness you should have on the flange for a composite design floor system when welding rods?

Calif

 

[Calif]

I meant not to say rods but studs on a beam.

 

[Floodwall]

Try

http://www.Engineering-International.com

and look for "composite floor beam" excel spreadsheet.

Matt

 

[dik]

Yes there are... a min/max length based on the topping thickness as well as a min/max diameter based on the beam flange thickness... I don't have my book at home... but will provide the info next week if you still require it. The text on composite design may have the info already...

Dik