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CFVR4705 - CALTRANS: Seismic Analysis Y-axis

Seismic Analysis on a 1 DOF beam according to CALTRANS. (soil profile type D, structure within 10 miles of an active fault)

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: CFVR4705.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4705'
  /TITLE, %NomFile%, CALTRANS: Seismic Analysis Y-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,0.3,E1,1,10,0.5

! ----------------------------------------------------------------------
! 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%)y'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)y'

   AR25=12*AR20*AR23/L**3     	! Bending stiffness 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,VERTICAL,NONE,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,Y
 ! 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)=  44.2627
   VALUE(39,1)=  72.0446
   VALUE(38,1)= 132.7882
   VALUE(37,1)= 199.1822
   VALUE(36,1)= 326.7907
   VALUE(35,1)= 365.5991
   VALUE(34,1)= 369.2484
   VALUE(33,1)= 378.2736
   VALUE(32,1)= 369.8070
   VALUE(31,1)= 356.0032
   VALUE(30,1)= 320.2525
   VALUE(29,1)= 291.4225
   VALUE(28,1)= 271.0009
   VALUE(27,1)= 238.0776
   VALUE(26,1)= 214.1693
   VALUE(25,1)= 181.2322
   VALUE(24,1)= 143.2260
   VALUE(23,1)= 143.2260
   VALUE(22,1)= 143.2260
   VALUE(21,1)= 143.2260

! 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 143.23 143.231.000 0.1
Sa(2)y 143.23 143.231.000 0.1
Sa(3)y 143.23 143.231.000 0.1
Sa(4)y 143.23 143.231.000 0.1
Sa(5)y 181.25 181.251.000 0.1
Sa(6)y 214.17 214.171.000 0.1
Sa(7)y 238.07 238.071.000 0.1
Sa(8)y 270.99 270.991.000 0.1
Sa(9)y 291.44 291.441.000 0.1
Sa(10)y 320.24 320.241.000 0.1
Sa(11)y 355.99 355.991.000 0.1
Sa(12)y 369.8 369.81.000 0.1
Sa(13)y 378.27 378.271.000 0.1
Sa(14)y 369.25 369.251.000 0.1
Sa(15)y 365.6 365.61.000 0.1
Sa(16)y 326.79 326.791.000 0.1
Sa(17)y 199.18 199.181.000 0.1
Sa(18)y 132.79 132.791.000 0.1
Sa(19)y 72.045 72.0451.000 0.1
Sa(20)y 44.263 44.2631.000 0.1
Sa(1)y 143.23 143.231.000 0.1
Sa(2)y 143.23 143.231.000 0.1
Sa(3)y 143.23 143.231.000 0.1
Sa(4)y 143.23 143.231.000 0.1
Sa(5)y 181.23 181.251.000 0.1
Sa(6)y 214.17 214.171.000 0.1
Sa(7)y 238.08 238.071.000 0.1
Sa(8)y 271 270.991.000 0.1
Sa(9)y 291.42 291.441.000 0.1
Sa(10)y 320.25 320.241.000 0.1
Sa(11)y 356 355.991.000 0.1
Sa(12)y 369.81 369.81.000 0.1
Sa(13)y 378.27 378.271.000 0.1
Sa(14)y 369.25 369.251.000 0.1
Sa(15)y 365.6 365.61.000 0.1
Sa(16)y 326.79 326.791.000 0.1
Sa(17)y 199.18 199.181.000 0.1
Sa(18)y 132.79 132.791.000 0.1
Sa(19)y 72.045 72.0451.000 0.1
Sa(20)y 44.263 44.2631.000 0.1

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