Composite Beam in SMF Design

[gzdee]

Hello everyone,

I am a MSc student and designing a SMF building on Etabs, but I am having hard times with designing steel decking with a concrete topping. My structure has moment connections in perimeter and rest of the column-beam connections are all pinned.I am assigning floor as filled deck section on ETABS but it has shear studs and as I know this shear studs help floor to work together with the beams so beams act as composite beams.

But at the same time as I read in 'NEHRP Seismic Design Technical Brief No. 2, Steel Special Moment Frames Guide for practicing engineers', Beams should not be designed as composite with supported concrete slabs as the composite behavior is not available when the top flange is in tension and also because AISC 341, §9.2d prohibits placement of shear studs in the zone of anticipated plastic hinging (see Section 7.2).

So I am so confused understanding composite beam in SMF, maybe I read too much and I am confusing myself. But can you please help me with understanding ıt? For example can I model gravity beams and secondary beams which has got pinned ends as Composite Beams or can I use shear studs in Steel Special Moment Frame? I hope I could explain myself. Thank you.

 

[JoshPlumSE]

Composite beams are fine for SMF buildings..... Just don't use them for your main SMF beams. You can have some studs in those beams to ensure connectivity between diaphragm and structure. But, nowhere near the protected zones.

 

[gzdee]

So, I can design secondary beams and beams that are part of the gravity-framing system as composite beams but the primary girders that have moment connection shouldn't show conposite behavior, but some studs to provide connectivity at those girders also OK. Did I understand right?

Thank you for your answer. Helped a lot