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CFVR4901 - PS 92: Seismic Analysis (elastic spectrum) X-axis

Seismic Analysis on a 1 DOF beam according to PS 92

This example compares spectrum accelerations given by CivilFEM to accelerations obtained when solving on a 1 DOF beam and to the correct PS 92 spectum accelerations.
The model is 1 element beam with only 1 DOF, which direction the CivilFEM spectrum is set (the rest of the DOF are constrained). A different mass is applied at the free end of the beam for the beam period to be equal to the 20 CivilFEM spectrum points. After solving, the mass acceleration is obtained and compared to the CivilFEM spectrum acceleration and to the correct value. Therefore, this example checks the following results:

  • CivilFEM spectrum is defined correctly by comparing to the correct value
  • CivilFEM spectrum is applied correctly and response acceleration is equal to spectrum acceleration

Element types used in the model: BEAM4, MASS21

Needed CivilFEM Modules:
Geotechnical Module
Bridges and Civil Non Linearities Module
Advanced Prestressed Concrete Module

The example can be launched on an educational license.
KEYWORDS
Seismic
PS 92

Model Statistics
Number of elements 1
Number of nodes 2
Number of civil materials 1
Number of cross sections 1
Number of shell vertices 0

Log file: CFVR4901.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4901'
  /TITLE, %NomFile%, PS 92: Seismic Analysis (elastic spectrum) X-axis
! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! CivilFEM Setup: Code & Units
~UNITS,,LENG,CM
~UNITS,,TIME,S
~UNITS,,FORC,KP
~CODESEL,,,,,PS92
/PREP7
! Preprocessor
! ----------------------------------------------------------------------
! Materials: A-42
 ~CFMP,1,LIB,STEEL,EA,A42
! Modify density (Rho = 0)
 ~CFMP,1,USER
 ~CFMP,1,DatGen,RHO,,0
! Element Types
  ET,1,BEAM4   ! Type 1: 3D Beam
  ET,2,MASS21  ! Type 2: Mass
! Sections
 ~SSECLIB,1,1,1,1   !IPE 80
 ~BMSHPRO,1,BEAM,1,1,,,4,,0,,

! Nodes
  L = 10            ! L    : Bar length
  N, 1
  N,10,L

! Elements
  TYPE,1
  MAT ,1
  REAL,1
  EN,1,1,10
  EPLOT

! Parameters
  *GET,AR20,EX,1         		         ! Ex   : Elastic Modulus
  ~CFGET,AR22,SECTION,1,MECHPROP,A,,2    ! Area : Bar area
  ~CFGET,AR23,SECTION,1,MECHPROP,IZZ,,2  ! Izz  : Moment of inertia
  ~CFGET,AR24,SECTION,1,MECHPROP,IYY,,2  ! Iyy  : Moment of inertia
  pi = 3.141592654

! Seismic Spectrum
  ~DEFSPEC,ALL,0.1*981,S0,ELASTIC,1,5

! ----------------------------------------------------------------------
! DATA CHECK
! ----------------------------------------------------------------------
! Data comparison number
  NComp = 40
  NComp_ch = 0

! Marix dim.
  *DIM,LABEL,CHAR,Ncomp,1
  *DIM,LABEL_CH,CHAR,Ncomp_ch,1
  *DIM,VALUE,,Ncomp,3
  *DIM,VALUE_CH,CHAR,Ncomp_ch,3
  *DIM,TOLER,,Ncomp,2

*DO,ARG1,1,20,1
   /PREP7
   ~CFGET,AR26,SEISM,,SPEC,TH,,ARG1,1   ! Period
  ! Labels
   LABEL(ARG1,1) = 'Sa(%ARG1%)x'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)x'

   AR25=AR20*AR22/L
   AR27=AR25*(AR26/(2*pi))**2  	! Mass applied at end
   R,2,AR27
   TYPE,2
   MAT, 1
   REAL,2
   EN,2,10
   FINISH
   /SOLU

 ! Solution
 ! ---------------------------------------------------------------------
 ! Displacements
   D,1,,,,,,ALL
   D,10,,,,,,UY,UZ,ROTX,ROTY,ROTZ
   ~MODLSOL,1
   ~CMBMOD,HORIZONT,NONE,NONE,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,X
 ! Correct values
   VALUE(20-ARG1+1,1)=ARG5*AR25/AR27 			 ! Aceleration
 ! Obtained values
   ~CFGET,VALUE(20-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,1	 ! Y components of elastic horizontal spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,1	 ! Y components of elastic horizontal spectrum
   ! CivilFEM gives the spectrum Normalized by gravity.
   ! To compare it must be changed to acceleration user units.
   VALUE(20-ARG1+1,2) = VALUE(20-ARG1+1,2)*981
   VALUE(40-ARG1+1,2) = VALUE(40-ARG1+1,2)*981

   /PREP7
   EDELE,2
*ENDDO

! Correct values
! ----------------------------------------------------------------------
   VALUE(40,1)= 1.962000
   VALUE(39,1)= 2.546097
   VALUE(38,1)= 3.435884
   VALUE(37,1)= 4.888839
   VALUE(36,1)= 7.503965
   VALUE(35,1)= 12.954711
   VALUE(34,1)= 27.556180
   VALUE(33,1)= 32.340659
   VALUE(32,1)= 39.135638
   VALUE(31,1)= 49.545455
   VALUE(30,1)= 67.500000
   VALUE(29,1)= 105.863309
   VALUE(28,1)= 245.250000
   VALUE(27,1)= 245.250000
   VALUE(26,1)= 224.228571
   VALUE(25,1)= 203.207143
   VALUE(24,1)= 182.185714
   VALUE(23,1)= 161.164286
   VALUE(22,1)= 140.142857
   VALUE(21,1)= 119.121429

! Warning and error tolerances
! ----------------------------------------------------------------------
   *DO,II,1,NComp
     TOLER(II, 1)= 0.1 $ TOLER(II, 2)= 0.1
   *ENDDO

! ----------------------------------------------------------------------
! Results Comparison
! ----------------------------------------------------------------------
  COMPARA.MAC

Results

LabelTargetCivilFEMRatioTolerance
Sa(1)x 119.12 119.121.000 0.1
Sa(2)x 140.14 140.141.000 0.1
Sa(3)x 161.16 161.161.000 0.1
Sa(4)x 182.19 182.191.000 0.1
Sa(5)x 203.21 203.211.000 0.1
Sa(6)x 224.23 224.231.000 0.1
Sa(7)x 245.25 245.251.000 0.1
Sa(8)x 245.25 245.251.000 0.1
Sa(9)x 105.86 105.861.000 0.1
Sa(10)x 67.5 67.51.000 0.1
Sa(11)x 49.545 49.5451.000 0.1
Sa(12)x 39.136 39.1361.000 0.1
Sa(13)x 32.341 32.3411.000 0.1
Sa(14)x 27.556 27.5561.000 0.1
Sa(15)x 12.971 12.9711.000 0.1
Sa(16)x 7.5133 7.51331.000 0.1
Sa(17)x 4.8949 4.8951.000 0.1
Sa(18)x 3.4402 3.44021.000 0.1
Sa(19)x 2.5493 2.54931.000 0.1
Sa(20)x 1.9644 1.96451.000 0.1
Sa(1)x 119.12 119.121.000 0.1
Sa(2)x 140.14 140.141.000 0.1
Sa(3)x 161.16 161.161.000 0.1
Sa(4)x 182.19 182.191.000 0.1
Sa(5)x 203.21 203.211.000 0.1
Sa(6)x 224.23 224.231.000 0.1
Sa(7)x 245.25 245.251.000 0.1
Sa(8)x 245.25 245.251.000 0.1
Sa(9)x 105.86 105.861.000 0.1
Sa(10)x 67.5 67.51.000 0.1
Sa(11)x 49.545 49.5451.000 0.1
Sa(12)x 39.136 39.1361.000 0.1
Sa(13)x 32.341 32.3411.000 0.1
Sa(14)x 27.556 27.5561.000 0.1
Sa(15)x 12.955 12.9710.999 0.1
Sa(16)x 7.504 7.51330.999 0.1
Sa(17)x 4.8888 4.8950.999 0.1
Sa(18)x 3.4359 3.44020.999 0.1
Sa(19)x 2.5461 2.54930.999 0.1
Sa(20)x 1.962 1.96450.999 0.1


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