In reference to the X-U Universal Knurled Shank & X-P Premium concrete fasteners technical supplement (attached for reference), are the ultimate values listed in the design charts for tension and shear ultimate in the sense that they can be used with LRFD or ultimate in the sense of the average of the tested load to failure?
Hello Ryan,
The values listed in the X-U Universal Knurled Shank & X-P Premium Concrete Fasteners Technical Supplement follow the ASD methodology. This is supported by the reference of safety factors in the footnotes of the tables to go from ultimate loads to allowable loads. Additionally, depending on which exact table you may be referencing, the testing standard used to obtain the published values is noted as well (most common in this document is ICC-ES AC 70).
I hope this helps! Please reach out to hnatechnicalservices@hilti.com for any additional questions.
Kind regards,
Sinan
Hi Sinan,
Thanks for the response, but unfortunately, I don't think I asked my question correctly. Let's use table 1 and table 2 as an example. I see that below table 2 the "allowable" loads are calculated using a factor of safety equal to 5. I would use this capacity and compare it to a required demand based on ASD load combinations. What I would like to know is if the "Ultimate" capacities in Table 1 can be used with LRFD required demands?
To me that doesn't seem correct. My guess is that "ultimate" is some sort of average of value of a load test taken to failure, but I don't let me bias the response.
I don't think many people have access to ICC-ES AC 70 (myself included), so if you don't mind summarizing the results and possibly providing some background on what "ultimate" means, that would very helpful. Thank you!
Hi Ryan,
The values presented in the document all follow the ASD methodology, where the mean ultimate load is determined from a given number of individual tests. Safety factors are applied to the ultimate loads to achieve allowable loads. Some additional verbiage regarding evaluation of test data is available in Section 2.2 of the Direct Fastening Technical Guide. Reference of these values for an LRFD methodology would be at the discretion and judgement of the Engineer of Record.
Kind regards,
Sinan