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CFVR4802 - UBC 97: Seismic Analysis (maximum spectrum) Y-axis

Seismic Analysis on a 1 DOF beam according to UBC 97

This example compares spectrum accelerations given by CivilFEM to accelerations obtained when solving on a 1 DOF beam and to the correct UBC 97 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
UBC 97

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: CFVR4802.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4802'
  /TITLE, %NomFile%, UBC 97: Seismic Analysis (maximum spectrum) Y-axis

! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! CivilFEM Setup: Code & Units
~UNITS,,LENG,CM
~UNITS,,TIME,S
~UNITS,,FORC,KP
~CODESEL,,,,,UBC97
/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

! Seismic Spectrum
  ~DEFSPEC,ALL,2A,B,MAXIMUM,B,5,2/3

  pi = 3.141592654

! ----------------------------------------------------------------------
! 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
   /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 maximum spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,2	 ! Y components of maximum 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) = 136.11375
   VALUE(39,1) = 149.39314
   VALUE(38,1) = 165.54375
   VALUE(37,1) = 185.60966
   VALUE(36,1) = 211.21099
   VALUE(35,1) = 245.00475
   VALUE(34,1) = 291.67232
   VALUE(33,1) = 360.30110
   VALUE(32,1) = 471.16298
   VALUE(31,1) = 680.56875
   VALUE(30,1) = 680.56875
   VALUE(29,1) = 639.73463
   VALUE(28,1) = 598.90050
   VALUE(27,1) = 558.06638
   VALUE(26,1) = 517.23225
   VALUE(25,1) = 476.39813
   VALUE(24,1) = 435.56400
   VALUE(23,1) = 394.72988
   VALUE(22,1) = 353.89575
   VALUE(21,1) = 313.06163

! 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 313.06 313.061.000 0.1
Sa(2)y 353.9 353.91.000 0.1
Sa(3)y 394.73 394.731.000 0.1
Sa(4)y 435.56 435.561.000 0.1
Sa(5)y 476.4 476.41.000 0.1
Sa(6)y 517.23 517.231.000 0.1
Sa(7)y 558.07 558.071.000 0.1
Sa(8)y 598.9 598.91.000 0.1
Sa(9)y 639.74 639.731.000 0.1
Sa(10)y 680.57 680.571.000 0.1
Sa(11)y 680.57 680.571.000 0.1
Sa(12)y 471.16 471.161.000 0.1
Sa(13)y 360.3 360.31.000 0.1
Sa(14)y 291.67 291.671.000 0.1
Sa(15)y 245 2451.000 0.1
Sa(16)y 211.21 211.211.000 0.1
Sa(17)y 185.61 185.611.000 0.1
Sa(18)y 165.54 165.541.000 0.1
Sa(19)y 149.39 149.391.000 0.1
Sa(20)y 136.11 136.111.000 0.1
Sa(1)y 313.06 313.061.000 0.1
Sa(2)y 353.9 353.91.000 0.1
Sa(3)y 394.73 394.731.000 0.1
Sa(4)y 435.56 435.561.000 0.1
Sa(5)y 476.4 476.41.000 0.1
Sa(6)y 517.23 517.231.000 0.1
Sa(7)y 558.07 558.071.000 0.1
Sa(8)y 598.9 598.91.000 0.1
Sa(9)y 639.73 639.731.000 0.1
Sa(10)y 680.57 680.571.000 0.1
Sa(11)y 680.57 680.571.000 0.1
Sa(12)y 471.16 471.161.000 0.1
Sa(13)y 360.3 360.31.000 0.1
Sa(14)y 291.67 291.671.000 0.1
Sa(15)y 245 2451.000 0.1
Sa(16)y 211.21 211.211.000 0.1
Sa(17)y 185.61 185.611.000 0.1
Sa(18)y 165.54 165.541.000 0.1
Sa(19)y 149.39 149.391.000 0.1
Sa(20)y 136.11 136.111.000 0.1


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