How to set up a multi-point response spectrum (MPRS) analysis?
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Below is an ANSYS Release 10.0 input file for a multi-point response spectrum. To do a MPRS, you specify all of conditions for one excitation (type, location, direction, spectral curve, etc.) and then issue a PFACT command for that condition. You then repeat this procedure for each loading condition. After all of the loading conditions have been defined, you issue one SOLVE command. You then read the MCOM file into /POST1 to combine the results and calculate the overall response. ! Simple Three Beam Fixed-Fixed Frame ! Frame is excited at two locations (different direction each location) nmodes = 5 /prep7 et,1,188 mp,ex,1,10e6 mp,prxy,1,.3 mp,dens,1,1e-3 sectype,1,beam,rect secdata,1,1 n,1 n,2,0,10 n,3,10,10 n,4,10 e,1,2 e,2,3 e,3,4 d,all,uz,0 d,1,all,0 d,4,all,0 ! Do modal analysis and extract min and max frequecny /solu antype,modal modopt,lanb,nmodes mxpand,nmodes,,,yes solve *get,min_fr,mode,1,freq *get,max_fr,mode,nmodes,freq /post1 set,list ! list modes ! Do MPRS ! Excite N1 in the X direction and N4 in the Y direction /solu antype,spectrum spopt,mprs,nmodes,yes ! X direction excitation of N1 psdunit,1,disp ! type of response spectrum d,1,ux,1 ! location and direction of excitation psdfrq,1,1,min_fr*1/2,max_fr*2 ! frequency points for spectrum curve psdval,1,1,1 ! spectrum values (constant) pfact,1,base ! performs linear static analysis to ! calculate participation factors ! Y direction excitation of N4 psdunit,2,disp d,4,uy,1 psdfrq,2,2,min_fr*1/2,max_fr*2 psdval,2,1,1 pfact,2,base srss ! SRSS mode combination method solve ! Results are written to the mode combination file (Jobname.MCOM) ! in the form of POST1 commands. These commands calculate the overall ! response of the structure by combining the maximum modal responses. ! To calculate the overall response, execute the commands stored on ! the MCOM file. /post1 /input,,mcom prnsol,dof fini /exit ! Sample MCOM file LCOPER,ZERO LCDEFI,1, 1, 1 LCFACT,1, 0.786588E-01 LCASE,1 LCOPER,SQUARE LCDEFI,1, 1, 2 LCFACT,1, 0.774597E-01 LCOPER,ADD,1,MULT,1 LCDEFI,1, 1, 3 LCFACT,1, 0.669663E-01 LCOPER,ADD,1,MULT,1 LCDEFI,1, 1, 5 LCFACT,1, 0.236453E-01 LCOPER,ADD,1,MULT,1 LCOPER,SQRT |
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