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CFVR4903 - PS 92: Seismic Analysis (elastic spectrum) Z-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: CFVR4903.DAT


   FINISH
  ~CFCLEAR,,1
   NomFile='CFVR4903'
  /TITLE, %NomFile%, PS 92: Seismic Analysis (elastic spectrum) Z-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,S2,ELASTIC,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,,ARG1,1       ! Period
  ! Labels
   LABEL(ARG1,1) = 'Sa(%ARG1%)z'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)z'

   AR25=12*AR20*AR24/L**3     ! Bending rigidity around Y axis
   AR27=AR25*(AR26/(2*pi))**2  ! Mass applied at end
   R,2,0,0,AR27
   TYPE,2
   MAT, 1
   REAL,2
   EN,2,10
   FINISH
   /SOLU

 ! Solution
 ! ---------------------------------------------------------------------
 ! Displacements
   D,1,,,,,,ALL
   D,10,,,,,UX,UY,,ROTX,ROTY,ROTZ
   ~MODLSOL,1
   ~CMBMOD,NONE,NONE,HORIZONT,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,Z
 ! Correct values
   VALUE(20-ARG1+1,1)=ARG5*AR25/AR27 ! Acceleration
 ! 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) = 5.10120
   VALUE(39,1) = 6.33291
   VALUE(38,1) = 8.07120
   VALUE(37,1) = 10.63733
   VALUE(36,1) = 14.65441
   VALUE(35,1) = 21.46462
   VALUE(34,1) = 34.39870
   VALUE(33,1) = 40.03073
   VALUE(32,1) = 47.86807
   VALUE(31,1) = 59.52135
   VALUE(30,1) = 78.67426
   VALUE(29,1) = 116.00146
   VALUE(28,1) = 220.72500
   VALUE(27,1) = 220.72500
   VALUE(26,1) = 201.80571
   VALUE(25,1) = 182.88643
   VALUE(24,1) = 163.96714
   VALUE(23,1) = 145.04786
   VALUE(22,1) = 126.12857
   VALUE(21,1) = 107.20929

! 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)z 107.21 107.211.000 0.1
Sa(2)z 126.13 126.131.000 0.1
Sa(3)z 145.05 145.051.000 0.1
Sa(4)z 163.97 163.971.000 0.1
Sa(5)z 182.89 182.891.000 0.1
Sa(6)z 201.81 201.811.000 0.1
Sa(7)z 220.73 220.721.000 0.1
Sa(8)z 220.72 220.721.000 0.1
Sa(9)z 116 1161.000 0.1
Sa(10)z 78.674 78.6741.000 0.1
Sa(11)z 59.521 59.5211.000 0.1
Sa(12)z 47.868 47.8681.000 0.1
Sa(13)z 40.031 40.0311.000 0.1
Sa(14)z 34.399 34.3991.000 0.1
Sa(15)z 21.454 21.4541.000 0.1
Sa(16)z 14.647 14.6471.000 0.1
Sa(17)z 10.632 10.6321.000 0.1
Sa(18)z 8.0673 8.06731.000 0.1
Sa(19)z 6.3299 6.32991.000 0.1
Sa(20)z 5.0987 5.09871.000 0.1
Sa(1)z 107.21 107.211.000 0.1
Sa(2)z 126.13 126.131.000 0.1
Sa(3)z 145.05 145.051.000 0.1
Sa(4)z 163.97 163.971.000 0.1
Sa(5)z 182.89 182.891.000 0.1
Sa(6)z 201.81 201.811.000 0.1
Sa(7)z 220.72 220.721.000 0.1
Sa(8)z 220.72 220.721.000 0.1
Sa(9)z 116 1161.000 0.1
Sa(10)z 78.674 78.6741.000 0.1
Sa(11)z 59.521 59.5211.000 0.1
Sa(12)z 47.868 47.8681.000 0.1
Sa(13)z 40.031 40.0311.000 0.1
Sa(14)z 34.399 34.3991.000 0.1
Sa(15)z 21.465 21.4541.000 0.1
Sa(16)z 14.654 14.6471.000 0.1
Sa(17)z 10.637 10.6321.000 0.1
Sa(18)z 8.0712 8.06731.000 0.1
Sa(19)z 6.3329 6.32991.000 0.1
Sa(20)z 5.1012 5.09871.000 0.1


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