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CFVR1813 - NCSE 02: Seismic Analysis (Linear spectrum) Z-axis

Seismic Analysis on a 1 DOF beam according to NCSE 02

This example compares spectrum accelerations given by CivilFEM to accelerations obtained when solving on a 1 DOF beam and to the correct NCSE 02 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 iqual 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
NCSE 02

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: CFVR1813.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR1813'
  /TITLE, %NomFile%, NCSE02: Seismic Analysis (Linear spectrum) Z-axis

! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! CivilFEM Setup: Code & Units
  ~UNITS,,LENG,CM
  ~UNITS,,TIME,S
  ~UNITS,,FORC,KP
  ~CODESEL,,,,,NCSE02
/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,,Steel

! 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 definition
  ~DEFSPEC,ALL,0.13,I,ELASTIC,1,1,4,4

  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,,ARG1,1   ! 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

 ! 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 ! Aceleration
 ! Obtained values
   ~CFGET,VALUE(20-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,1	 ! Y components of elastic horizontal spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,1	 ! Y components of elastic 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) =  28.58
   VALUE(39,1) =  57.16
   VALUE(38,1) =  85.76
   VALUE(37,1) = 114.32
   VALUE(36,1) = 142.92
   VALUE(35,1) = 171.52
   VALUE(34,1) = 200.08
   VALUE(33,1) = 228.68
   VALUE(32,1) = 257.24
   VALUE(31,1) = 285.84
   VALUE(30,1) = 285.84
   VALUE(29,1) = 267.71121
   VALUE(28,1) = 249.58464
   VALUE(27,1) = 231.45806
   VALUE(26,1) = 213.33149
   VALUE(25,1) = 195.20492
   VALUE(24,1) = 177.07834
   VALUE(23,1) = 158.95177
   VALUE(22,1) = 140.82520
   VALUE(21,1) = 122.69862

! Warning and error tolerances
! ----------------------------------------------------------------------
   *DO,II,1,40
     TOLER(II, 1)= 1.0 $ TOLER(II, 2)= 1.0
   *ENDDO

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

Results

LabelTargetCivilFEMRatioTolerance
Sa(1)z 122.7 122.71.000 1
Sa(2)z 140.83 140.831.000 1
Sa(3)z 158.95 158.951.000 1
Sa(4)z 177.08 177.081.000 1
Sa(5)z 195.21 195.21.000 1
Sa(6)z 213.33 213.331.000 1
Sa(7)z 231.46 231.461.000 1
Sa(8)z 249.58 249.581.000 1
Sa(9)z 267.71 267.711.000 1
Sa(10)z 285.84 285.841.000 1
Sa(11)z 285.84 285.841.000 1
Sa(12)z 257.25 257.251.000 1
Sa(13)z 228.67 228.671.000 1
Sa(14)z 200.09 200.091.000 1
Sa(15)z 171.5 171.51.000 1
Sa(16)z 142.92 142.921.000 1
Sa(17)z 114.34 114.341.000 1
Sa(18)z 85.751 85.7511.000 1
Sa(19)z 57.168 57.1681.000 1
Sa(20)z 28.584 28.5841.000 1
Sa(1)z 122.7 122.71.000 1
Sa(2)z 140.83 140.831.000 1
Sa(3)z 158.95 158.951.000 1
Sa(4)z 177.08 177.081.000 1
Sa(5)z 195.2 195.21.000 1
Sa(6)z 213.33 213.331.000 1
Sa(7)z 231.46 231.461.000 1
Sa(8)z 249.58 249.581.000 1
Sa(9)z 267.71 267.711.000 1
Sa(10)z 285.84 285.841.000 1
Sa(11)z 285.84 285.841.000 1
Sa(12)z 257.24 257.251.000 1
Sa(13)z 228.68 228.671.000 1
Sa(14)z 200.08 200.091.000 1
Sa(15)z 171.52 171.51.000 1
Sa(16)z 142.92 142.921.000 1
Sa(17)z 114.32 114.341.000 1
Sa(18)z 85.76 85.7511.000 1
Sa(19)z 57.16 57.1681.000 1
Sa(20)z 28.58 28.5841.000 1


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