Left

CivilFEM Online Help

Right

CFVR4801 - UBC 97: Seismic Analysis (maximum spectrum) X-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: CFVR4801.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4801'
  /TITLE, %NomFile%, UBC 97: Seismic Analysis (maximum spectrum) X-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
  pi = 3.141592654

! Seismic Spectrum
  ~DEFSPEC,ALL,1,A,MAXIMUM,A,7.5,2/3

! ----------------------------------------------------------------------
! 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,TH,,ARG1,2   ! Period
  ! Labels
   LABEL(ARG1,1) = 'Sa(%ARG1%)x'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)x'

   AR25=AR20*AR22/L
   AR27=AR25*(AR26/(2*pi))**2  	! Mass applied at end
   R,2,AR27
   TYPE,2
   MAT, 1
   REAL,2
   EN,2,10
   FINISH
   /SOLU

 ! Solution
 ! ---------------------------------------------------------------------
 ! Displacements
   D,1,,,,,,ALL
   D,10,,,,,,UY,UZ,ROTX,ROTY,ROTZ
   ~MODLSOL,1
   ~CMBMOD,HORIZONT,NONE,NONE,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,X
 ! Correct values
   VALUE(20-ARG1+1,1)=ARG5*AR25/AR27 			 ! Aceleration
 ! Obtained values
   ~CFGET,VALUE(20-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,2	 ! Y components of maximum horizontal spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,2	 ! Y components of maximum 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)=  77.759946
   VALUE(39,1)=  85.346282
   VALUE(38,1)=  94.572907
   VALUE(37,1)= 106.036290
   VALUE(36,1)= 120.661985
   VALUE(35,1)= 139.967903
   VALUE(34,1)= 166.628456
   VALUE(33,1)= 205.835151
   VALUE(32,1)= 269.169044
   VALUE(31,1)= 388.799730
   VALUE(30,1)= 388.799734
   VALUE(29,1)= 365.471750
   VALUE(28,1)= 342.143766
   VALUE(27,1)= 318.815782
   VALUE(26,1)= 295.487797
   VALUE(25,1)= 272.159813
   VALUE(24,1)= 248.831829
   VALUE(23,1)= 225.503845
   VALUE(22,1)= 202.175860
   VALUE(21,1)= 178.847876

! 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)x 178.85 178.851.000 0.1
Sa(2)x 202.18 202.181.000 0.1
Sa(3)x 225.5 225.51.000 0.1
Sa(4)x 248.83 248.831.000 0.1
Sa(5)x 272.16 272.161.000 0.1
Sa(6)x 295.49 295.491.000 0.1
Sa(7)x 318.82 318.821.000 0.1
Sa(8)x 342.14 342.141.000 0.1
Sa(9)x 365.47 365.471.000 0.1
Sa(10)x 388.8 388.81.000 0.1
Sa(11)x 388.8 388.81.000 0.1
Sa(12)x 269.17 269.171.000 0.1
Sa(13)x 205.84 205.841.000 0.1
Sa(14)x 166.63 166.631.000 0.1
Sa(15)x 139.97 139.971.000 0.1
Sa(16)x 120.66 120.661.000 0.1
Sa(17)x 106.04 106.041.000 0.1
Sa(18)x 94.573 94.5731.000 0.1
Sa(19)x 85.346 85.3461.000 0.1
Sa(20)x 77.76 77.761.000 0.1
Sa(1)x 178.85 178.851.000 0.1
Sa(2)x 202.18 202.181.000 0.1
Sa(3)x 225.5 225.51.000 0.1
Sa(4)x 248.83 248.831.000 0.1
Sa(5)x 272.16 272.161.000 0.1
Sa(6)x 295.49 295.491.000 0.1
Sa(7)x 318.82 318.821.000 0.1
Sa(8)x 342.14 342.141.000 0.1
Sa(9)x 365.47 365.471.000 0.1
Sa(10)x 388.8 388.81.000 0.1
Sa(11)x 388.8 388.81.000 0.1
Sa(12)x 269.17 269.171.000 0.1
Sa(13)x 205.84 205.841.000 0.1
Sa(14)x 166.63 166.631.000 0.1
Sa(15)x 139.97 139.971.000 0.1
Sa(16)x 120.66 120.661.000 0.1
Sa(17)x 106.04 106.041.000 0.1
Sa(18)x 94.573 94.5731.000 0.1
Sa(19)x 85.346 85.3461.000 0.1
Sa(20)x 77.76 77.761.000 0.1


Contains proprietary and confidential information of Ingeciber, S.A.