Two-way slab in steel structure

[Sm1448]

Hi, I'm designing a steel structure without secondary beams and want to use two-way slab for stories. Should I define roofs as shell-thin or membrane ?
How can I connect the concrete slab to steel beams?

 

[271828]

Have you considered one of the long span composite slab systems like comslab? They can go up to about 30 ft.

 

[Sm1448]

Thanks for your help. But for some reason I have to use a two-way slab.
In Etbas modeling, it should be of the membrane type or shell-thin?

 

[centondollar]

If you do not know the difference between plate (bending) and membrane (thin slab) models, you should ask your colleagues to guide you.

A helpful hint: think about how the load is applied. Does the floor slab take loads predominantly perpendicular to its plane, or predominantly in its plane? The answer to that question provides the answer to what type of element you should use.

 

[MIStructE_IRE]

What do you mean “for some reason?”

I’m not sure about your part of the world, but insitu slab with steel frame is very dated construction here. No contractor wants to erect a steel frame, then get the formwork guys in, erect falsework, get the steel fixers in then the concrete gangs, pour the slab and then repeat cycle.

Composite concrete filled metal deck on steel frame - job done.

Again - YMMV, but I can’t see the logic in a two way insitu slab on steel frame.

 

[271828]

But for some reason I have to use a two-way slab.

From that, I assume someone above you is defining what this system must be. I recommend having them pin down the details better.

 

[Sm1448]

What do you mean “for some reason?”

This is just an academic project and it is not going to be construct. The professor also forced us to use a two-way slab. Unfortunately, in our university, professors do not advise on projects at all and only want the result.

You left out the main question and only paid attention to the parts that did not matter.
There is no question of constructing a project at all, I just want to know how to model a two-way slab in ETABS for steel structure.

 

[hokie66]

My only answer is "beats me". Perhaps your professor needs to go back to school to learn something about structures.

 

[ThomasH]

This is just an academic project and it is not going to be construct. The professor also forced us to use a two-way slab. Unfortunately, in our university, professors do not advise on projects at all and only want the result.

You left out the main question and only paid attention to the parts that did not matter.
There is no question of constructing a project at all, I just want to know how to model a two-way slab in ETABS for steel structure.

You have to forums that might be more suitable for your question. The first is for studend questions, the second is for Etabs questions.

And I suspect that the professor does not just want the result. He also wants you to learn something from the exercise . The systems you are studying are fundamentally different.

Thomas

 

[milkshakelake]

As far as I know, there’s no simple way to do it in ETABS. Combining frame and shell elements will add stiffness to the two way slab. Check out the SAP2000 examples, maybe one example fits your situation.

There’s a hacky way to do it. Add a 1’ story level between the beams and slab. Connect them together with pinned vertical members at 1’ on center. Add a lateral restraint support to the slab and possibly steel.