Exist. Concrete Floor Slab
Exist. Concrete Floor Slab
(OP)
We're replacing a mechanical unit in a second story mechanical room at a school built in the late 1950s.
According to the existing drawings, the floor construction is "2.5 inch concrete slab on Steeltex Floor Lath". The floor framing below this slab is SJ146 joists spaced not to exceed 2.5 feet.
Although my first concern was the allowable capacity of the existing floor joists, I am not wondering about the span of the floor slab between the joists. Is there any way to determine the capacity of this unreinforced floor?
According to the existing drawings, the floor construction is "2.5 inch concrete slab on Steeltex Floor Lath". The floor framing below this slab is SJ146 joists spaced not to exceed 2.5 feet.
Although my first concern was the allowable capacity of the existing floor joists, I am not wondering about the span of the floor slab between the joists. Is there any way to determine the capacity of this unreinforced floor?






RE: Exist. Concrete Floor Slab
"Is there any way to determine the capacity of this unreinforced floor?" Try Chapter 22: Structural Plain Concrete of the ACI or a comparable present day form deck capacity (assuming the depth and spacing of flutes are known).
RE: Exist. Concrete Floor Slab
RE: Exist. Concrete Floor Slab
RE: Exist. Concrete Floor Slab
SO if there is no existing equipment pad, you could add a 6" pad on to the existing slab, and reinforce your pad to span from joist to joist. Then the strength of the slab is not relevant for the wieght of the unit.
RE: Exist. Concrete Floor Slab
BA
RE: Exist. Concrete Floor Slab
If it helps avoid the need for joist strenghtening then you may want to look at providing a steel spreader beam above the joists that transfers the load to as many joists as necessary. It is often possible to do this without taking up too much space or creating a great deal of trip hazards.
RE: Exist. Concrete Floor Slab
Are you certain the floor is unreinforced? There are a lot of 2 1/2" floor slabs around, placed on non-composite corrugated deck and reinforced with light wire fabric. It alway was difficult to justify their behaviour based on normal reinforced concrete design practice, but most have performed satisfactorily.
RE: Exist. Concrete Floor Slab
http://www.ivysteel.com/lathing_products.htm
It looks as though it is normally used in swimming pools. Legally, I would think the mesh is worthless because of lack of code bond. I could understand if there was a structural element underneath, and the concrete for finishing.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Exist. Concrete Floor Slab
BA
RE: Exist. Concrete Floor Slab