A nonlinear transient analysis is performed using the HHT time-integration method. Load steps 1 through 4 are performed statically. Transient effects are included in load step 5.

antype,trans                  ! Select transient analysis
nlgeom,on                     ! Include geometric nonlinearities 
trnopt,full, , , , ,HHT       ! Use HHT algorithm to include transient effect
tintp,0.15                    ! Specify amplitude decay factor