Waiting links

$F_1(z), F_2(z)$ - force versus length relation; $c_1(z,t), c_2(z,t)$ - damage parameters.

$$F_1(z) = Y s_1(\alpha) \left(\frac{z}{L} - 1\right)(1 - c_1)... ...$} \\ 0, & \mbox{if $z < \Delta$} \end{array} \right.$$ (2)

where

${d c_1(z,t) \over d t} = \left\{ \begin{array}{lll} v_d, \mbox{ if $z\geq z_{fail1}$ and $c_1(z,t)<1$ } \\ 0, \mbox{ otherwise } \end{array} \right.$	${d c_2(z,t) \over d t} = \left\{ \begin{array}{lll} v_d, \mbox{ if $z\ge... ...{fail2}$ and $c_2(z,t)<1$ } \\ 0, \mbox{ otherwise } \end{array} \right.$
$c_1(z,0) = 0$	$c_2(z,0) = 0$

and $z_{fail1}/L = z_{fail2}/\Delta$.

$$F(z) = F_1(z) + F_2(z)$$ (3)