Problem $6\mathrm{.}8$

A structure modeled as spring$-$mass shown in Fig. P$6\mathrm{.}8$b is subjected to the loading force depicted in

Fig. P$6\mathrm{.}8$a$.$ Assume elastoplastic behavior of Fig. P$6\mathrm{.}8$c$.$ Determine the response.

$6\mathrm{.}10$

Fig. P$6\mathrm{.}8$

Problem $6\mathrm{.}9$

Repeat Problem $6\mathrm{.}8$ assuming damping in the system equal to $20\%$ of the critical damping.