Eurocode 7 is law resource so access is free and i have copy and pasted the relevant clause to get some insight ;
7.5 Pile load tests
7.5.1 General (1)P Pile load tests shall be carried out in the following situations: — when using a type of pile or installation method for which there is no comparable experience; — when the piles have not been tested under comparable soil and loading conditions; — when the piles will be subject to loading for which theory and experience do not provide sufficient confidence in the design. The pile testing procedure shall then provide loading similar to the anticipated loading; — when observations during the process of installation indicate pile behaviour that deviates strongly and unfavourably from the behaviour anticipated on the basis of the site investigation or experience, and when additional ground investigations do not clarify the reasons for this deviation. (2) Pile load tests may be used to: — assess the suitability of the construction method; — determine the response of a representative pile and the surrounding ground to load, both in terms of settlement and limit load; — to allow judgement of the overall pile foundation. (3) Where load tests are not practical due to difficulties in modelling the variation in the load (e.g. cyclic loading) very cautious design values for the material properties should be used. (4)P If one pile load test is carried out, it shall normally be located where the most adverse ground conditions are believed to occur. If this is not possible, an allowance shall be made when deriving the characteristic value of the compressive resistance. (5)P If load tests are carried out on two or more test piles, the test locations shall be representative of the site of the pile foundation and one of the test piles shall be located where the most adverse ground conditions are believed to occur.
I remember one of the standard ;
-at least one pile for each case and each different diameter ;
-two piles after 200 total no. piles ,
- at least 0.5% of the total number of piles if the no of piles more than 500.
Thanks for your reply. But what I really want to know is that how much work piles should be check by static load test according American standards. For example，according Chinese standard Technical code for testing of building foundation piles cause 3.3.4: 1% but not less than 3 piles should be check by static load test in one project. Did American standards have similar requirements？
In the UK, there is no minimum standard on number of piles to be tested. For a lot of projects, static pile testing is too expensive given the size of the project and and cost of testing.
Generally it developed on a project by project basis. What HTURk proposed would be relatively standard in my experience.
Likins suggests (in perhaps this article: https://ascelibrary.org/doi/10.1061/40743(142)14) a correlation between factors of safety in the design and the quantity of piles load tested (and type of load test).
From his summary, I believe ASCE 20-96 and IBC were each non-specific when it came to a standard quantity of testing. I'm not sure if that has been changed since.
