Structural differences between Steel mesh reinforcement and Rebar reinforcement 1

[VTAdam]

Are there any differences between the usage of prefabricated welded reinforcement mesh and manually on site rebar reinforcement in a flat slab? So if we have a 250 mm flat slab with welded prefabricated mesh, would it behave in anyway shape or form better than the same exact slab but with rebar reinforcement that has been tied on the spot by a worker.

**Let's assume that there are no differences in the placement of the steel in the two slabs. They were meticulously executed and the only difference is that the connection points between the vertical and horizontal rebar are welded vs. tied.

Thanks in advance!

 

[jayrod12]

I'd be inclined to say no given your assumption of placement.

But be real, I've never seen mesh installed on site with the same amount of care and chairing that regular reinforcing gets.

 

[TehMightyEngineer]

I've often found wire mesh will be available in higher strengths for minimal cost differences (though WWR will always be a lot more than rebar), this can allow a reduction in reinforcement required. The welds at each bar might provide additional benefit vs wire ties.

Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries

http://www.americanconcrete.com

 

[KootK]

- Better crack control. Or maybe worse, I'm not sure. You'd have more, smaller reinforcing which is a plus. On the other hand, you'd have weak development between crossing wires.

- Different development length equations etc. Not much potential for development hooks etc.

- It might be difficult to adjust your rebar quantity per foot to match the lateral distribution of bending moments. I'd be reluctant to use it for top steel.

- Since WWM is often stronger than rebar, for the same tensile force resistance, you would get less stiffness and therefore possibly more deflection.

- You might be able to maximize your effective flexural depth better.

- Stud rail placement might be tricky.




I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[MacGruber22]

One thing I know about WWF - don't ever try to design it to be draped. Think you are being efficient by draping? You're not, as it will be built like a turd sandwich every time.

"It is imperative Cunth doesn't get his hands on those codes."

 

[Trenno]

Generally mesh isn't ductile. However I've seen mesh being offered in fy = 500 MPa these days...

 

[rapt]

If it is anything like Australian mesh, the ductility is very low (min 1.5% elongation in Australia where normal reinforcement is minimum 5% and Earthquake class is minimum 10%).

Because of this Australian type mesh cannot be used in any application that requires ductile action, so no redistribution, no robustness, no seismic action.

That pretty well limits its use!

PS If you let us know what country you are talking about it might make it easier to reply more specifically!

 

[Teguci]

I see welded wire reinforcement used a lot by precast concrete plants for double tee flange bending reinforcement and for the stems where added shear reinforcement is needed. I imagine the factory conditions help with keeping the placement of the reinforcement accurate.

One thing that hasn't been mentioned. If you have a supported concrete slab exposed to chlorides, the welded wire reinforcement will deteriorates without spalling the concrete. Failure has been sudden and without warning. Rebar will expand enough to pop the concrete and let people know there is a problem.