Section 27-708. Precast concrete piles (including prestressed sections)

(a)
  Materials. Materials for precast concrete piles  shall  conform  to  the
  requirements of article five of subchapter ten of this chapter.
    (b) Construction.
    (1)  HANDLING.  Precast  concrete  piles  shall be proportioned, cast,
  cured, handled, and driven so as  to  resist  the  stresses  induced  by
  handling  and  driving  as  well as by loads. Handling stresses shall be
  computed on the basis of fifty per cent of the weight of the pile as  an
  allowance  for  impact. Handling equipment shall be constructed so as to
  equalize the reactions on the several lines of the pile pickups. Loading
  conditions induced by handling and driving shall  be  considered  as  of
  infrequent occurrence.
    (2) DIMENSIONS. The minimum lateral dimension of the pile shall be ten
  inches, except for the taper at the tip.
    (3)  STRUCTURAL DESIGN. Piles shall be proportioned in accordance with
  the provisions of article eight  of  this  subchapter,  subject  to  the
  following additional requirements:
    a.  For  a  length  equal  to at least three times the minimum lateral
  dimension at each end of the pile, lateral tie reinforcement  consisting
  of 0.225 in. diameter rods or larger shall be spaced not more than three
  inches  center-to-center,  or  an  equivalent  spiral shall be provided.
  Elsewhere, the spacing of the ties or the pitch of  the  spiral  may  be
  increased   to   twelve   inches  The  minimum  amount  of  longitudinal
  reinforcement shall be two per cent of the concrete section placed in  a
  symmetrical  pattern  of  at  least  four bars. If prestressed piles are
  used, the minimum residual compression in  the  pile  section  shall  be
  seven hundred psi. For piles designed with voids, the three inch spacing
  of  the  ties  or spiral at each end of the pile shall be extended for a
  distance of twelve feet or one-third the length of the  pile,  whichever
  is smaller.
    b.  For  piles  designed with voids, the minimum wall thickness of the
  concrete in any section of the piles shall be  four  inches.  Voids  may
  extend  through  either  or  both  ends of the pile. If the void extends
  through the lower end of the pile, the pile  head  shall  be  vented  to
  prevent buildup of internal hydraulic pressure during driving.
    c.  Reinforcing  steel shall be covered with at least one and one-half
  inches of concrete on the surface against the ground.
    (c)  Tolerances.  Voids,  when   used,   shall   be   located   within
  three-eighths of an inch of the position shown in the plans. The maximum
  departure of the pile axis from a straight line, measured while the pile
  is not subject to bending forces, shall not exceed one-eighth of an inch
  in  ten  feet or three eighths of an inch in forty feet, or 0.1 per cent
  of the pile length.
    (d) Installation. Precast concrete  piles  shall  not  be  handled  or
  driven  until  they  have  cured  sufficiently  to develop the necessary
  strength.