Reinforced Concrete Help: Where To Place Steel Bars?

[sanado]

Hey guys, was just wondering if you could help me with re-inforced concrete. I am confused as to where to put the steel bars. I no that it needs to be placed in the part of the concrete that is under tension, but i can never find which part is under tension. An explanation would be good while some sample questions would be perfect!

 

[TVP45]

If you are unable to do beam/column calculations, you probably should not be doing rebar design.

 

[sanado]

Haha that would be an ideal world for me if i could skip this part of the physics course. Its just basic questions and it asks where should the steel beams be placed

 

[TVP45]

OK. Here's a link that will answer your questions.
http://www.info.usda.gov/CED/ftp/CED/tr67.pdf

 

[Lore]

Just wondering if that documents maybe a wee bit complex for what he's after TVP?

 

[TVP45]

Just wondering if that documents maybe a wee bit complex for what he's after TVP?

Well, maybe a skinch. I thought of referring him to BOCA, but that assumes a fair level of knowledge. It's a complex question; I can't imagine anyone asking this in an Intro Physics class. Do you know of any simpler reference he could use?

 

[ChillyWilly]

There needs to be more info on this. The part of the concrete in tension depends on the loads and their vectors or in reality the moments. However, to answer the last question "... any simpler reference..." any mechanics of materials undergrad book should have a section on reinforced concrete beams.

I have R. C. Hibbeler's Third Ed. pg. 326 has a good write up.

 

[th3plan]

I worked construction during the summer, when not in school , and for concrete , in garage, we put the bars parelel, and a few feet apart. That is what my company did, so i assume its right, cause no complaints lol

 

[ChillyWilly]

When you say parallel I'm asuming that you are talking about floors and parallel to the floor surface. That makes sense, but the placement of the rebar needs to be correct. In a parking floor you need the rebar 3/4 or so the thickness of the concrete slab from the top surface as this would be the part of the slab in tension. In other words the force on the concrete is (lets assume) perpendicular to the slab and it would make the slab bow and the under side would need to strech a bit.

 

[TVP45]

When you say parallel I'm asuming that you are talking about floors and parallel to the floor surface. That makes sense, but the placement of the rebar needs to be correct. In a parking floor you need the rebar 3/4 or so the thickness of the concrete slab from the top surface as this would be the part of the slab in tension. In other words the force on the concrete is (lets assume) perpendicular to the slab and it would make the slab bow and the under side would need to strech a bit.

The CRSI handbook for rebar placement is intended for contractors, ironworkers, etc. That would be simpler than my original posting.