2006 New York Code - Composite Piles.

 
    §  27-714 Composite piles. Composite piles include those consisting of
  two types of pile joined together. The maximum allowable load  shall  be
  that  allowed  for  the component of lesser strength used to make up the
  full pile length. The connection or joint  between  the  two  components
  shall  be  constructed  so as to prevent the separation of the upper and
  lower components during construction and  thereafter.  The  details  and
  methods of making joints shall be designed.