Steel Sheet Slab with Concrete-Check in Concentrated Load 1

[ITV]

Dear Sir,
i would like to check a steel sheet slab that has concrete above for concentrated big load. Load is 60kN in an area of 0,1x0,1m2. The total slab thickness is 16cm (from down part of steel sheet to top of concrete layer).
Steel sheet thickness is 1,25mm. (image linked)

 

[jayrod12]

that's only 0.6 kN using those units. Or is it 60 kN over 0.1mx0.1m? That is far different.

 

[ITV]

You have right, 60 kN in a small area of 0,1 x 0,1 m2. I corrected it
In fact its a Pallet racking system above a steel sheet and concrete slab.
It has 2 feet of 0,1x0,1m2 area each (that are very close one to another). So we have (to be more exact and sincere) 60kN that is distributed to 2 very close areas of 0,1x0,1m.
I was thinking to have a very big reinforcement: one layer of bars Φ14/10cm to each direction X and Y

 

[BAretired]

Draw a sketch. Your verbal description leaves much to be desired.

 

[ITV]

Thank you! Here you are!

 

[dik]

Thanks, is that a total of 40kN per pair of legs. and what is the supporting structure like? Where are the joists/purlins and where are the girders?

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[BAretired]

Please indicate what the red, gray, blue and green rectangles represent in the sketch below.
Also, what are dimensions A and B?

It appears to me that the area supporting three 60 kN loads is much larger than you have indicated.
It also appears that the flutes of the deck are spanning from left to right. I don't believe that the deck supports any of the 60kN loads.

 

[BAretired]

More exact? It's entirely different, and inconsistent. It's also incomplete. What type of floor exists outside the area of the steel deck?

i would like to check a steel sheet slab that has concrete above for concentrated big load. Load is 60kN in an area of 0,1x0,1m2. The total slab thickness is 16cm (from down part of steel sheet to top of concrete layer).
Steel sheet thickness is 1,25mm. (image linked)

There is no area of 100x100mm with a 60kN load. It isn't possible. If such a concentrated load existed on a slab, the pressure would be 60,000/10,000N/mm^2 or 6N/mm^2 or 6MPa, which is ridiculous.

Your latest sketch indicates 6x20 = 120 kN in an area of 2.37x2.97m^2 or 17kN/m^2, which is still a pretty heavy load for a slab.

You appear to have no idea what you are doing, and you are wasting our time by providing such a crappy description of your structure.

 

[ITV]

You have understood very well, my friend. You are an angel, THANK YOU for helping me. Yes. This is a 17kN/m^2. I STRONGLY APPOLOGISE for not providing you with a good sketch.

All i want you to see is the only the "detail part" in the following file i upload, and according to which Eurocode you would examine a concentrated load in a slab that is steel-sheet and concrete filling:
*see detail*

 

[BAretired]

You have understood very well, my friend. You are an angel, THANK YOU for helping me. Yes. This is a 17kN/m^2. I STRONGLY APPOLOGISE for not providing you with a good sketch.

All i want you to see is the only the "detail part" in the following file i upload, and according to which Eurocode you would examine a concentrated load in a slab that is steel-sheet and concrete filling:

Please remember that 17kN/m2, or 17kPa, is the value when the Racking palette load is spread uniformly over the entire area. Applying the load on separate feet is too much of a concentration and should not be considered.

You have not indicated the floor construction where there are no Racking palettes. I suggest you run the same system over the entire floor. As noted in the sketch below, you may even save money by using a lighter Symdeck 73, and spreading the load to reduce bending moment.

You might consider re-spacing columns and beams to take advantage of modularity with the Racking palettes. If the Racking palettes do not relate in a consistent way to the spacing of support beams, it seems to me to be a missed opportunity to simplify site placement. But that's just me!

PS I'm no angel!

 

[ITV]

PS you are!

 

[BAretired]

I have given names A to F to the gridlines which may or may not correspond with those used by the Architect, if there is one.

I suggest moving the racking structures horizontally (not vertically) to the locations shown by the red rectangles. That way, the racks align with the building columns and the beams align in a consistent way with the rack feet (columns). I can see no valid reason why the racks at A and F need access on both sides; the interior double racks don't have it.

 

[rapt]

If the metal decking is being considered to act as reinforcement, the published bond/strength of metal decking is often based on tests using distributed loads.

In that case it would be necessary to do special testing using concentrated loads to determine the decking performance under those loads.

 

[BAretired]

The only bottom steel in the slab is Symdeck 73, a 1.25mm thick composite steel deck. Bond may be a problem, but there are other issues as well. The photo below illustrates a similar racking system found on the internet.

The racking load is said to be 17kPa, a healthy floor load even when applied uniformly, but in our case, it is applied as a number of point loads. Dimension A, parallel to the deck flutes, is known but dimension B, the spacing of the supports is unknown, so the magnitude of the concentrated loads is unknown. Also, rack supports do not necessarily align with the steel floor beams.

Punching shear is going to be a problem wherever a rack support occurs over a hollow part of the deck flute.

Composite deck is essentially a one-way system, so it is not clear how large point loads can be distributed in the weak direction.

Some serious thought is required before this design is finalized.

 

[ITV]

Using company's software i can calculate Vrd1 .
Using Eurocode 2, Fig.6.13 i can calculate Vsd

I think and hope that problem is solved! Love you guys and thanks!!!!

 

[BAretired]

Yes ITV, thickening the slab in the racking bays is the best solution.