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CFVR4706 - CALTRANS: Seismic Analysis Z-axis

Seismic Analysis on a 1 DOF beam according to CALTRANS. (soil profile type B, structure with a fundamental period of vibration T>=1.5)

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

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: CFVR4706.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4706'
  /TITLE, %NomFile%, CALTRANS: Seismic Analysis Z-axis

! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! CivilFEM Setup: Code & Units
~UNITS,,LENG,CM
~UNITS,,TIME,S
~UNITS,,FORC,KP
~CODESEL,,,,,CALTRANS
/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,0.55,B2,2,5,0.75

! ----------------------------------------------------------------------
! DATA CHECK
! ----------------------------------------------------------------------
! Data comparision 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,TV,,ARG1,1   ! Period
  ! Labels
   LABEL(ARG1,1) = 'Sa(%ARG1%)z'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)z'

   AR25=12*AR20*AR24/L**3     	! Bending stiffness 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,VERTICAL,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,Z
 ! Correct values
   VALUE(20-ARG1+1,1)=ARG5*AR25/AR27 			 ! Aceleration
 ! Obtained values
   ~CFGET,VALUE(20-ARG1+1,2),SEISM,,SPEC,SDV,,ARG1,1	 ! Y components of linear horizontal spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDV,,ARG1,1	 ! Y components of linear 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)=   76.812300
   VALUE(39,1)=  122.687324
   VALUE(38,1)=  225.963741
   VALUE(37,1)=  330.116423
   VALUE(36,1)=  486.705020
   VALUE(35,1)=  618.050168
   VALUE(34,1)=  822.283999
   VALUE(33,1)=  938.720563
   VALUE(32,1)= 1033.396248
   VALUE(31,1)= 1046.243642
   VALUE(30,1)= 1029.484946
   VALUE(29,1)=  987.083063
   VALUE(28,1)=  940.402287
   VALUE(27,1)=  843.727078
   VALUE(26,1)=  754.034080
   VALUE(25,1)=  593.240748
   VALUE(24,1)=  404.846438
   VALUE(23,1)=  404.858113
   VALUE(22,1)=  404.867381
   VALUE(21,1)=  404.883225

! 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 404.88 404.881.000 0.1
Sa(2)z 404.88 404.881.000 0.1
Sa(3)z 404.85 404.851.000 0.1
Sa(4)z 404.85 404.851.000 0.1
Sa(5)z 593.24 593.241.000 0.1
Sa(6)z 754.03 754.031.000 0.1
Sa(7)z 843.72 843.721.000 0.1
Sa(8)z 940.4 940.41.000 0.1
Sa(9)z 987.08 987.081.000 0.1
Sa(10)z 1029.5 1029.51.000 0.1
Sa(11)z 1046.2 1046.21.000 0.1
Sa(12)z 1033.4 1033.41.000 0.1
Sa(13)z 938.7 938.711.000 0.1
Sa(14)z 822.31 822.311.000 0.1
Sa(15)z 618.03 618.031.000 0.1
Sa(16)z 486.69 486.691.000 0.1
Sa(17)z 330.12 330.121.000 0.1
Sa(18)z 225.98 225.981.000 0.1
Sa(19)z 122.68 122.681.000 0.1
Sa(20)z 76.812 76.8121.000 0.1
Sa(1)z 404.88 404.881.000 0.1
Sa(2)z 404.87 404.881.000 0.1
Sa(3)z 404.86 404.851.000 0.1
Sa(4)z 404.85 404.851.000 0.1
Sa(5)z 593.24 593.241.000 0.1
Sa(6)z 754.03 754.031.000 0.1
Sa(7)z 843.73 843.721.000 0.1
Sa(8)z 940.4 940.41.000 0.1
Sa(9)z 987.08 987.081.000 0.1
Sa(10)z 1029.5 1029.51.000 0.1
Sa(11)z 1046.2 1046.21.000 0.1
Sa(12)z 1033.4 1033.41.000 0.1
Sa(13)z 938.72 938.711.000 0.1
Sa(14)z 822.28 822.311.000 0.1
Sa(15)z 618.05 618.031.000 0.1
Sa(16)z 486.71 486.691.000 0.1
Sa(17)z 330.12 330.121.000 0.1
Sa(18)z 225.96 225.981.000 0.1
Sa(19)z 122.69 122.681.000 0.1
Sa(20)z 76.812 76.8121.000 0.1

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