Steel Fiber STRUCTURAL Slab
Steel Fiber STRUCTURAL Slab
(OP)
I have a 2-way structural slab, columns at 20'-0" on center, light storage loading. The contractor wants to eliminate the rebar in the slab and use steel fibers. He keeps mistakingly calling the 2-way slab a "slab-on-grade". I think this may be where he is mislead.
I do not know much about steel fiber reinforced slabs, except I thought they were used for slabs on grade for industrial applications (for high wheel loads, impact resistance). I did not think it could be used as a replacement for rebar in a structural slab.
Does anyone have any experience in fibers for structural slab? I don't think I would take the rebar out of a conc. beam and replace it with steel fibers, know what I mean?
And if anyone has done this, what is the design procedure for analyzing a steel fiber concrete slab/beam?
I do not know much about steel fiber reinforced slabs, except I thought they were used for slabs on grade for industrial applications (for high wheel loads, impact resistance). I did not think it could be used as a replacement for rebar in a structural slab.
Does anyone have any experience in fibers for structural slab? I don't think I would take the rebar out of a conc. beam and replace it with steel fibers, know what I mean?
And if anyone has done this, what is the design procedure for analyzing a steel fiber concrete slab/beam?






RE: Steel Fiber STRUCTURAL Slab
RE: Steel Fiber STRUCTURAL Slab
RE: Steel Fiber STRUCTURAL Slab
AEF
RE: Steel Fiber STRUCTURAL Slab
While the increase in tensile strength (and corresponding flexural strength) from fiber addition is substantial by proportion, it is not adequate to accommodate the flexural stresses typically imposed in unsupported slab applications.
RE: Steel Fiber STRUCTURAL Slab
RE: Steel Fiber STRUCTURAL Slab
RE: Steel Fiber STRUCTURAL Slab
The first slab system (designed and built in the 1960's) lasted until the mid-80's when it was replaced with essentially the same slab with reinforcing bars. This replacement slab cracked almost immediately due to a change in the loading criteria - much heavier forklifts and a higher loading rate.
We determined that the composite beams created a very high flexibility in the floor such that, when combined with the wheel loadings, initiated cracks. The owner was adamant that the new slab not crack.
Our design included new support columns and beams to reduce both the spans of the existing steel beams as well as the slab itself. This, by itself, eliminated the cracking stresses but we went a step further by specifiying fiber reinforcing in the slab (not to replace the reinforcing bars but to supplement them).
The fiber was a combination of steel and poly material. This was intended to increase the durability of the slab and further reduce crack sizes throughout.
So far, the deck has performed well.
RE: Steel Fiber STRUCTURAL Slab
RE: Steel Fiber STRUCTURAL Slab
RE: Steel Fiber STRUCTURAL Slab
I would suggest that there is quite a good analogy between fibre reinforced concrete and fruitcake (which Ron likes, as he has told us before).
In any fruitcake the amount of visible fruit on the cut surface of any slice is quite variable (even though there is usually sufficient fruit to provide the required overall flavour).
Similarly, the proportion of fibres in the tension zone of a suspended slab is basically uncontrolled and will be quite variable. At some sections it may be dangerously low and pose a structural risk (even though the general 'flavour' of crack-resistance is quite OK).
I support all those who say 'don't even think of using it as replacement for properly design structural reinforcement'.
RE: Steel Fiber STRUCTURAL Slab
This is great. From steel fibers to flavor of fruitcake. Excellent.
A followup - After reading all your posts and doing some research, I called the contractor and left a voicemail explaining what conditions we have, what the slab is expected to do, and why steel fiber reinforcement wouldnt work in this situation. Haven't heard a peep from the guy since.