C RKFTCO    SOURCE    AM        12/02/28    00:28:56     7289           
        FUNCTION rkftco(t,tmax)

c       Reduction of tension strength in siliceous concrete 
c     according to 3.2.2.2 (3) of prEN1992-1-2

      IMPLICIT REAL*8 (A-B,D-H,O-Z)
      implicit integer (I-K,M,N)
      implicit logical (L)
      implicit character*10 (C)
      
      i1 = 1
      r1 = 1.0d0
      r0 = 0.0d0
      precision = 1.0d-3

      if (tmax.le.100.d0) then
        ft = 1.0d0
      else if (tmax.le.600.d0) then
        ft = 1.00d0-(tmax-100.d0)/500.d0
      else
        ft = 0.0d0
      endif               

c     Attention to the cases where T<20 C et Tmax=20 C
      if ( (t.lt.tmax) .and. (dabs(tmax-20).ge.precision) ) then
c       Cooling down
c       calculate  ft(20øc) = rmul * ft(tmax)
        if (tmax.lt.300.) then
          rmul = r1-0.1*(tmax-20.)/280.
        else
          rmul = 0.9
        endif
        ft20 = rmul*ft
c       calculate fc(t) = interpolation between fc(20) and fc(tmax)
        ft = ft20+(ft-ft20)*(t-20.)/(tmax-20)
      endif

        rkftco = ft

        return
        end