subroutine rebar_bondslip_get_force(slip,dslip,dl,force,hsv,
     .  userparm,lawid,temp)
c     include 'bk06.inc'
      real hsv
      dimension hsv(12),cm(8),userparm(*)
c
        ys=userparm(1)
        yd=userparm(2)
        dia=userparm(3)
        stiff=ys/yd
c
        pi=3.1415926
        area=pi*dia*dl
c
        pshear=hsv(1)
c
        tshear=pshear+stiff*dslip
        atshear=abs(tshear)
c
c     check if elastic or plastic
c
        if(atshear.lt.ys) then
          shear=tshear
        else
          shear=tshear*ys/atshear
        end if
c
        force=shear*area
c
        hsv(1)=shear
c
      return
      end