A nonlinear transient analysis is performed to 3.35E-4 seconds. Large-deflection effects are enabled (NLGEOM,ON). Because the problem undergoes a large plastic deformation, a large plastic limit is introduced as a cutback factor (CUTCONTROL) to reduce the step size when the solution encounters convergence difficulties during the nonlinear analysis.

antype,4                  ! Analysis type is transient
nlgeom,on                 ! Include geometric nonlinearities 
trnopt,full,,,,,hht       ! HHT time integration method
tintp,0.1                 ! Numerical Damping
cutcontrol,plslimit,.9    ! Cutback criterion