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CFVR4605 - EAK 2000: Seismic Analysis (design spectrum) Y-axis

Seismic Analysis on a 1 DOF beam according to EAK 2000

This example compares spectrum accelerations given by CivilFEM to accelerations obtained when solving on a 1 DOF beam and to the correct EAK 2000 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
EAK 2000

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: CFVR4605.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4605'
  /TITLE, %NomFile%, EAK 2000: Seismic Analysis (design spectrum) Y-axis
! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! CivilFEM Setup: Code & Units
~UNITS,,LENG,CM
~UNITS,,TIME,S
~UNITS,,FORC,KP
~CODESEL,,,,,EAK2000
/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,I,A,DESIGN,1,5,1.3,0.9

  pi=3.141592654

! ----------------------------------------------------------------------
! DATA CHECK
! ----------------------------------------------------------------------
! Data comparision 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%)y'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)y'

   AR25=12*AR20*AR23/L**3      ! Bending rigidity around Z axis
   AR27=AR25*(AR26/(2*pi))**2  ! Mass applied at end
   R,2,0,AR27
   TYPE,2
   MAT, 1
   REAL,2
   EN,2,10
   FINISH
   /SOLU

 ! Displacements
   D,1,,,,,,ALL
   D,10,,,,,UX, ,UZ,ROTX,ROTY,ROTZ
   ~MODLSOL,1
   ~CMBMOD,NONE,HORIZONT,NONE,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,Y
 ! 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) =  74.18386513
  VALUE(39,1) = 117.75954554
  VALUE(38,1) = 154.30865778
  VALUE(37,1) = 186.93162647
  VALUE(36,1) = 216.91493752
  VALUE(35,1) = 244.94972569
  VALUE(34,1) = 271.46144124
  VALUE(33,1) = 296.73546050
  VALUE(32,1) = 320.97494280
  VALUE(31,1) = 344.33100000
  VALUE(30,1) = 344.33100000
  VALUE(29,1) = 325.21871827
  VALUE(28,1) = 306.07200000
  VALUE(27,1) = 286.90234010
  VALUE(26,1) = 267.79004919
  VALUE(25,1) = 248.68350000
  VALUE(24,1) = 229.55400000
  VALUE(23,1) = 210.43023942
  VALUE(22,1) = 191.29500000
  VALUE(21,1) = 172.16550000

! 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)y 172.17 172.171.000 0.1
Sa(2)y 191.29 191.291.000 0.1
Sa(3)y 210.42 210.421.000 0.1
Sa(4)y 229.55 229.551.000 0.1
Sa(5)y 248.68 248.681.000 0.1
Sa(6)y 267.81 267.811.000 0.1
Sa(7)y 286.94 286.941.000 0.1
Sa(8)y 306.07 306.071.000 0.1
Sa(9)y 325.2 325.21.000 0.1
Sa(10)y 344.33 344.331.000 0.1
Sa(11)y 344.33 344.331.000 0.1
Sa(12)y 320.98 320.971.000 0.1
Sa(13)y 296.74 296.741.000 0.1
Sa(14)y 271.46 271.461.000 0.1
Sa(15)y 244.95 244.951.000 0.1
Sa(16)y 216.92 216.911.000 0.1
Sa(17)y 186.93 186.931.000 0.1
Sa(18)y 154.31 154.311.000 0.1
Sa(19)y 117.76 117.761.000 0.1
Sa(20)y 74.184 74.1841.000 0.1
Sa(1)y 172.17 172.171.000 0.1
Sa(2)y 191.29 191.291.000 0.1
Sa(3)y 210.43 210.421.000 0.1
Sa(4)y 229.55 229.551.000 0.1
Sa(5)y 248.68 248.681.000 0.1
Sa(6)y 267.79 267.811.000 0.1
Sa(7)y 286.9 286.941.000 0.1
Sa(8)y 306.07 306.071.000 0.1
Sa(9)y 325.22 325.21.000 0.1
Sa(10)y 344.33 344.331.000 0.1
Sa(11)y 344.33 344.331.000 0.1
Sa(12)y 320.97 320.971.000 0.1
Sa(13)y 296.74 296.741.000 0.1
Sa(14)y 271.46 271.461.000 0.1
Sa(15)y 244.95 244.951.000 0.1
Sa(16)y 216.91 216.911.000 0.1
Sa(17)y 186.93 186.931.000 0.1
Sa(18)y 154.31 154.311.000 0.1
Sa(19)y 117.76 117.761.000 0.1
Sa(20)y 74.184 74.1841.000 0.1


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