Robertson Q Decking NKX 18-18 1

[NativeEngineer]

I'm evaluating a Robertson Decking system that is about 30 years old. HH Robertson doesn't have, or didn't look very hard for, the load tables. Does anyone have on hand the load tables for the Robertson Q decking type NKX 18-18? If so could you provide the capacity for an 11' span and a 12' span? Thanks.
I'm aware of the property tables for this type of decking and have used that to calculate capacity, but the numbers seem low or high. Not what would be expected

 

[msquared48]

Interesting point.

I looked thru my old Robertson catalogues and found the deck mentioned with section properties, some diaphragm shear values, but no span/load tables.

I also searched the ICBO reports 2739, and 1388, finding what you are looking for in 1388, page 15 of 28, Section D. The report is dated November 1980.

For the spans you mentionfor the QL-NKX 18-18 the superimposed loads with a 2.5" concrete fill are:

11' - 203 psf, and
12' - 186psf.

Get a copy of the ICBO report for your calcs. I could fax you a copy of the particular page if there were some way for us to communicate outside of this forum. Maybe thru the administrator?

Mike McCann
McCann Engineering

 

[NativeEngineer]

Mike,
thanks for the information. The deck i have has a 2" concrete fill, sorry for not providing all the information. I'm not able to find the ICBO 1388 online or through the icc-es website.

 

[msquared48]

I believe that the Robertson manual has the section properties of the deck though. I realize this may be complicated, but you might to be able to see what the capacity would be with the 2" infill if you calc'd by hand. Could justify your method with the 2.5" infill table values, then recalc for the 2" infill. Just a thought.

Let me know what you want to do.

Mike McCann
McCann Engineering

 

[msquared48]

I did notice too in the Q-Lock Floors Technical Data Book, that it does have a design example on pages 8 and 9 you might be able to use as a model. Do you have a copy of this publication?

The Q-Floor/Taproute System Technical Data Guide has the section properties listed. Do you have a copy of this?

Mike McCann
McCann Engineering

 

[NativeEngineer]

I don't have either the technical data book or the technical data guide. I will check with my supervisors if either has them.
A quick question about the superimposed loads you provided. Are those the allowable Live Loads with a 2.5" concrete fill?
If so then backing that out for 2" of fill shouldn't be too difficult. Basically what i'm analyzing is the capacity of the decking subtracting the concrete since it is 30 years old and has subsequent cracking and spalling.

 

[msquared48]

Yes, it is 2.5" of concrete.

Mike McCann
McCann Engineering

 

[msquared48]

Remember that the deck and concrete were originally a composite structural entity. The loads I quoted you are based on that composite action still existing. Are you saying the composite action has been compromised? If so, then you can only rely on the deck as you suggest, but backing off the figure with the lesser concrete figure will not give you what you are looking for if the composite action has been lost. You will need to work off the deck section properties alone,figuring the concrete infill as a live load to the deck.

Mike McCann
McCann Engineering

 

[NativeEngineer]

Thanks Mike, i have a request in with the system administrator to provide you with my fax number. The numbers you provided will help me in the meantime though.