C DFHARDCC  SOURCE    AM        12/02/27    23:39:36     7289           
      FUNCTION dfhardCC(rkappac,fc,fc0,rkappa1,ac,bc)

c     This subroutine calculates the derivative of the compressive 
c     hardening function with respect to rkappac

      IMPLICIT REAL*8 (A-B,D-H,O-Z)
      implicit integer (I-K,M,N)
      implicit logical (L)
      implicit character*10 (C)

      r0 = 0.
      hc = bc
   
      if (rkappac.le.rkappa1) then
        rn = (rkappac/rkappa1)
        rloc = 2.*(fc-fc0)*rn/(1.0d0+(rn*rn))
        ry = (dexp(ac*rkappac))*(fc0+rloc)
        rloc2 = 2.*(fc-fc0)*(1.0d0-(rn*rn))/
     .          (rkappa1*(1.0d0+(rn*rn))*(1.0d0+(rn*rn)))
        dry = ac*ry + (dexp(ac*rkappac))*rloc2
      else
        rloc = (1.0d0 + hc*(rkappac-rkappa1)) * 
     .    (dexp(-bc*(rkappac-rkappa1)))
        ry = (dexp(ac*rkappac))*fc*rloc
        rloc2 = fc * (hc-bc-hc*bc*(rkappac-rkappa1))
        dry = ac*ry + (dexp((ac-bc)*rkappac + bc*rkappa1)) * rloc2
      endif

      dfhardcc = dry

      RETURN
      END