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CFVR4905 - PS 92: Seismic Analysis (design 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: CFVR4905.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4905'
  /TITLE, %NomFile%, PS 92: Seismic Analysis (design 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

! Spectrum definition
  ~DEFSPEC,ALL,0.1*981,S0,DESIGN,1,5
  pi = 3.141592654

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

! Matrix 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
   /PREP7
   ~CFGET,AR26,SEISM,,SPEC,TH,,ARG1,2   ! 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 ! Acceleration
 ! Obtained values
   ~CFGET,VALUE(20-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,2	 ! Y components of design horizontal spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,2	 ! Y components of design 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) = 6.31937
   VALUE(39,1) = 7.28055
   VALUE(38,1) = 8.49901
   VALUE(37,1) = 10.07990
   VALUE(36,1) = 12.18995
   VALUE(35,1) = 15.10731
   VALUE(34,1) = 19.32710
   VALUE(33,1) = 25.80753
   VALUE(32,1) = 36.62556
   VALUE(31,1) = 57.08818
   VALUE(30,1) = 61.18004
   VALUE(29,1) = 66.09377
   VALUE(28,1) = 72.12987
   VALUE(27,1) = 79.76396
   VALUE(26,1) = 89.80155
   VALUE(25,1) = 103.73756
   VALUE(24,1) = 124.73837
   VALUE(23,1) = 161.08066
   VALUE(22,1) = 245.25000
   VALUE(21,1) = 245.25000

! 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 245.25 245.251.000 0.1
Sa(2)x 245.25 245.251.000 0.1
Sa(3)x 161.13 161.131.000 0.1
Sa(4)x 124.78 124.781.000 0.1
Sa(5)x 103.77 103.771.000 0.1
Sa(6)x 89.83 89.831.000 0.1
Sa(7)x 79.789 79.7891.000 0.1
Sa(8)x 72.153 72.1521.000 0.1
Sa(9)x 66.115 66.1141.000 0.1
Sa(10)x 61.199 61.1991.000 0.1
Sa(11)x 57.106 57.1061.000 0.1
Sa(12)x 36.642 36.6421.000 0.1
Sa(13)x 25.819 25.8191.000 0.1
Sa(14)x 19.336 19.3361.000 0.1
Sa(15)x 15.114 15.1141.000 0.1
Sa(16)x 12.195 12.1951.000 0.1
Sa(17)x 10.084 10.0841.000 0.1
Sa(18)x 8.5028 8.50281.000 0.1
Sa(19)x 7.2838 7.28381.000 0.1
Sa(20)x 6.3222 6.32221.000 0.1
Sa(1)x 245.25 245.251.000 0.1
Sa(2)x 245.25 245.251.000 0.1
Sa(3)x 161.08 161.131.000 0.1
Sa(4)x 124.74 124.781.000 0.1
Sa(5)x 103.74 103.771.000 0.1
Sa(6)x 89.802 89.831.000 0.1
Sa(7)x 79.764 79.7891.000 0.1
Sa(8)x 72.13 72.1521.000 0.1
Sa(9)x 66.094 66.1141.000 0.1
Sa(10)x 61.18 61.1991.000 0.1
Sa(11)x 57.088 57.1061.000 0.1
Sa(12)x 36.626 36.6421.000 0.1
Sa(13)x 25.808 25.8191.000 0.1
Sa(14)x 19.327 19.3361.000 0.1
Sa(15)x 15.107 15.1141.000 0.1
Sa(16)x 12.19 12.1951.000 0.1
Sa(17)x 10.08 10.0841.000 0.1
Sa(18)x 8.499 8.50281.000 0.1
Sa(19)x 7.2805 7.28381.000 0.1
Sa(20)x 6.3194 6.32221.000 0.1


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