NYC Building Code Presumptive Load Bearing Values

[DTS419]

The NYC Building code gives presumptive load bearing values for soil types that are considerably higher than the presumptive bearing values of the IRC/IBC codes. The Data Book for Civil Engineers by Elwyn E. Seele cited these values from the NYC code back in the 1940s-1950s in a manner that seemed to suggest they were more widely applicable.

Can anyone pride any insight in to why these values are so much higher in the NYC code, and to what extent can they be used beyond NYC? Not looking at this from a code jurisdiction point of view, but rather practically speaking, is it realistic to expect similar bearing capacities elsewhere?

Chapter 18 Soils and Foundations: Soils and Foundations, New York State Building Code 2020 | UpCodes

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[DTS419]

Just realized I copied the link for the NY State building code by mistake above. Here is the link to the NYC code, page 257...

https://www.nyc.gov/html/dob/downloads/bldgs_code/bc27s11.pdf

 

[DTS419]

No thoughts on this??

 

[CarlB]

It appears the NYC code goes into quite a bit more detail on soil types, variations in density, etc. than the IBC. And cautions that in addition to meeting the bearing values, designer needs to ensure that settlement will be withing acceptable ranges. So perhaps geotechnical engineers and their reports to not rely on the presumptive values provided.

The IBC values appear to be based on more of worse case/conservative approach, where the soil may be loose, and also consider limiting settlement in setting the values.