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Yes, it could be done by the ‘big mass method.’ A demonstration of the big mass method is given below. The final plot in the time-history postprocessor shows that a unit acceleration time history has been produced at the beam support location. /prep7 et,1,4 r,1,.1,.01,.01,.05,.05 mp,ex,1,1e7 mp,dens,1,.00025 n,1 n,11,50 fill e,1,2 *repeat,10,1,1 et,2,21 r,2,,1250 ! big mass in y direction only type,2 real,2 e,1 d,1,all ddele,1,uy ! constrain all but y direction fini /solu antype,trans omega=100 ! 100 radians/sec *do,tval,.001,.1,.001 f,1,fy,1250*sin(omega*tval) ! to produce a(y) = 1*sin(wt) time,tval solve *enddo fini /post26 nsol,2,1,uy deriv,3,2,1 deriv,4,3,1 plva,4 ! verify s