Left

CivilFEM Online Help

Right

CFVR4908 - PS 92: Seismic Analysis (design spectrum) X-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: CFVR4908.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4908'
  /TITLE, %NomFile%, PS 92: Seismic Analysis (design spectrum) Z-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,S3,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%)z'
   LABEL(20+ARG1,1) = 'Sa(%ARG1%)z'

   AR25=12*AR20*AR24/L**3      ! Bending rigidity 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,HORIZONT,0,0.0001
 ! Query results
   *GET,ARG5,NODE,10,U,Z
 ! 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
   /PREP7
   ! 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
   EDELE,2
*ENDDO

! Correct values
! ----------------------------------------------------------------------
 VALUE(40,1)= 17.520919
 VALUE(39,1)= 19.485610
 VALUE(38,1)= 21.828114
 VALUE(37,1)= 24.656057
 VALUE(36,1)= 28.119357
 VALUE(35,1)= 32.432250
 VALUE(34,1)= 37.910162
 VALUE(33,1)= 45.034247
 VALUE(32,1)= 54.570420
 VALUE(31,1)= 67.545015
 VALUE(30,1)= 71.853898
 VALUE(29,1)= 76.922918
 VALUE(28,1)= 82.992125
 VALUE(27,1)= 90.419858
 VALUE(26,1)= 99.768517
 VALUE(25,1)= 111.979811
 VALUE(24,1)= 128.774274
 VALUE(23,1)= 153.712188
 VALUE(22,1)= 196.200000
 VALUE(21,1)= 196.200000

! Warning and error tolerances
! ----------------------------------------------------------------------
   *DO,II,1,NComp
     TOLER(II, 1)= 1.0 $ TOLER(II, 2)= 1.0
   *ENDDO

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

Results

LabelTargetCivilFEMRatioTolerance
Sa(1)z 196.2 196.21.000 1
Sa(2)z 196.2 196.21.000 1
Sa(3)z 154.07 154.071.000 1
Sa(4)z 129.08 129.071.000 1
Sa(5)z 112.24 112.241.000 1
Sa(6)z 100 1001.000 1
Sa(7)z 90.631 90.6311.000 1
Sa(8)z 83.186 83.1861.000 1
Sa(9)z 77.102 77.1021.000 1
Sa(10)z 72.022 72.0221.000 1
Sa(11)z 67.703 67.7031.000 1
Sa(12)z 54.489 54.4891.000 1
Sa(13)z 44.967 44.9671.000 1
Sa(14)z 37.854 37.8541.000 1
Sa(15)z 32.384 32.3841.000 1
Sa(16)z 28.078 28.0781.000 1
Sa(17)z 24.619 24.6191.000 1
Sa(18)z 21.796 21.7961.000 1
Sa(19)z 19.457 19.4571.000 1
Sa(20)z 17.495 17.4951.000 1
Sa(1)z 196.2 196.21.000 1
Sa(2)z 196.2 196.21.000 1
Sa(3)z 153.71 154.070.998 1
Sa(4)z 128.77 129.070.998 1
Sa(5)z 111.98 112.240.998 1
Sa(6)z 99.769 1000.998 1
Sa(7)z 90.42 90.6310.998 1
Sa(8)z 82.992 83.1860.998 1
Sa(9)z 76.923 77.1020.998 1
Sa(10)z 71.854 72.0220.998 1
Sa(11)z 67.545 67.7030.998 1
Sa(12)z 54.57 54.4891.002 1
Sa(13)z 45.034 44.9671.002 1
Sa(14)z 37.91 37.8541.002 1
Sa(15)z 32.432 32.3841.002 1
Sa(16)z 28.119 28.0781.002 1
Sa(17)z 24.656 24.6191.002 1
Sa(18)z 21.828 21.7961.002 1
Sa(19)z 19.486 19.4571.002 1
Sa(20)z 17.521 17.4951.002 1


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