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CFVR4906 - PS 92: Seismic Analysis (design spectrum) Y-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: CFVR4906.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4906'
  /TITLE, %NomFile%, PS 92: Seismic Analysis (design spectrum) Y-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,S1,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%)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

 ! Solution
 ! ---------------------------------------------------------------------
 ! 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) =  9.17259
  VALUE(39,1) = 10.45580
  VALUE(38,1) = 12.05241
  VALUE(37,1) = 14.07821
  VALUE(36,1) = 16.70950
  VALUE(35,1) = 20.22629
  VALUE(34,1) = 25.09696
  VALUE(33,1) = 32.15781
  VALUE(32,1) = 43.03412
  VALUE(31,1) = 61.43859
  VALUE(30,1) = 65.77397
  VALUE(29,1) = 70.96501
  VALUE(28,1) = 77.31839
  VALUE(27,1) = 85.31547
  VALUE(26,1) = 95.76242
  VALUE(25,1) = 110.13248
  VALUE(24,1) = 131.47536
  VALUE(23,1) = 167.46200
  VALUE(22,1) = 245.25000
  VALUE(21,1) = 245.25000

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

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

Results

LabelTargetCivilFEMRatioTolerance
Sa(1)y 245.25 245.251.000 1
Sa(2)y 245.25 245.251.000 1
Sa(3)y 167.12 167.121.000 1
Sa(4)y 131.21 131.211.000 1
Sa(5)y 109.91 109.911.000 1
Sa(6)y 95.566 95.5661.000 1
Sa(7)y 85.14 85.141.000 1
Sa(8)y 77.16 77.161.000 1
Sa(9)y 70.819 70.8191.000 1
Sa(10)y 65.639 65.6391.000 1
Sa(11)y 61.313 61.3131.000 1
Sa(12)y 43.065 43.0651.000 1
Sa(13)y 32.181 32.1811.000 1
Sa(14)y 25.115 25.1151.000 1
Sa(15)y 20.241 20.2411.000 1
Sa(16)y 16.721 16.7211.000 1
Sa(17)y 14.088 14.0881.000 1
Sa(18)y 12.061 12.0611.000 1
Sa(19)y 10.463 10.4631.000 1
Sa(20)y 9.1791 9.17911.000 1
Sa(1)y 245.25 245.251.000 1
Sa(2)y 245.25 245.251.000 1
Sa(3)y 167.46 167.121.002 1
Sa(4)y 131.48 131.211.002 1
Sa(5)y 110.13 109.911.002 1
Sa(6)y 95.762 95.5661.002 1
Sa(7)y 85.315 85.141.002 1
Sa(8)y 77.318 77.161.002 1
Sa(9)y 70.965 70.8191.002 1
Sa(10)y 65.774 65.6391.002 1
Sa(11)y 61.439 61.3131.002 1
Sa(12)y 43.034 43.0650.999 1
Sa(13)y 32.158 32.1810.999 1
Sa(14)y 25.097 25.1150.999 1
Sa(15)y 20.226 20.2410.999 1
Sa(16)y 16.709 16.7210.999 1
Sa(17)y 14.078 14.0880.999 1
Sa(18)y 12.052 12.0610.999 1
Sa(19)y 10.456 10.4630.999 1
Sa(20)y 9.1726 9.17910.999 1

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