Left

CivilFEM Online Help

Right

CFVR1709 - Eurocode 8-2004: Horizontal type 2 elastic spectrum

Seismic Analysis on a 1 DOF beam according to Eurocode 8

This example compares spectrum accelerations given by CivilFEM to accelerations obtained when solving on a 1 DOF beam and to the correct Eurocode spectrum accelerations.
The model is a single beam element with only one degree of freedom: horizontal displacement at one of its ends. The beam has no mass. A punctual mass is applied at the free end of the beam.
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.
The spectrum is defined with the following parameters:
  • Horizontal
  • Elastic
  • Type 2
  • Soil type C
  • 7% Damping
  • Base acceleration of 1.2753 cm/s2

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
Eurocode 8

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: CFVR1709.DAT


   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR1709'
  /TITLE, %NomFile%, Eurocode 8-2004: Horizontal type 2 elastic spectrum

! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! Setup: Code & Units
~UNITS,,LENG,CM
~UNITS,,TIME,S
~UNITS,,FORC,KP
~CODESEL,EC3-92,EC2-91,,,EC8-04
/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,EXX,EX,1         		               ! Ex   : Elastic Modulus
  ~CFGET,IZZ,SECTION,1,MECHPROP,IZZ,,2   ! Izz  : Moment of inertia
  ~CFGET,IYY,SECTION,1,MECHPROP,IYY,,2   ! Iyy  : Moment of inertia

! Seismic Spectrum
  ~DEFSPEC,ALL,1.2753,C,ELASTIC,2,1,1,7

  pi=3.141592654

! ----------------------------------------------------------------------
! DATA CHECK
! ----------------------------------------------------------------------
! Data comparison 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,II,1,20
   /PREP7
   ~CFGET,Per,SEISM,,SPEC,TH,,II,2       ! Period
		 ! Labels
			LABEL(   II,1) = 'Sa(%II%)y'
			LABEL(20+II,1) = 'Sa(%II%)y'
			K=12*EXX*IZZ/L**3        ! Bending stiffness around Z axis
			Mass=K*(Per/(2*pi))**2   ! Mass applied at end
			R,2,0,Mass,0
   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,DispY,NODE,10,U,Y
 ! Correct values
   VALUE(20-II+1,1)=DispY*K/Mass ! Acceleration
 ! Obtained values
   ~CFGET,VALUE(20-II+1,2),SEISM,,SPEC,SDH,,II,2	 ! Y components of spectrum
   ~CFGET,VALUE(40-II+1,2),SEISM,,SPEC,SDH,,II,2	 ! Y components of spectrum
   ! CivilFEM gives the spectrum Normalized by gravity.
   ! To compare it must be changed to acceleration user units.
   VALUE(20-II+1,2) = VALUE(20-II+1,2)*981
   VALUE(40-II+1,2) = VALUE(40-II+1,2)*981
   /PREP7
   EDELE,2
*ENDDO

! Correct values
! ----------------------------------------------------------------------
   VALUE(21,1) = 2.2633  ! T=0.014s
   VALUE(22,1) = 2.6137
   VALUE(23,1) = 2.9641
   VALUE(24,1) = 3.3145
   VALUE(25,1) = 3.6649
   VALUE(26,1) = 4.0153
   VALUE(27,1) = 4.3657  ! TB=0.1s
   VALUE(28,1) = 4.3657  ! TC=0.25s
   VALUE(29,1) = 2.6729
   VALUE(30,1) = 1.9260
   VALUE(31,1) = 1.5054
   VALUE(32,1) = 1.2356
   VALUE(33,1) = 1.0478
   VALUE(34,1) = 0.9095  ! TD=1.2s
   VALUE(35,1) = 0.1842
   VALUE(36,1) = 0.0767
   VALUE(37,1) = 0.0418
   VALUE(38,1) = 0.0262
   VALUE(39,1) = 0.0180
   VALUE(40,1) = 0.0131  ! T=10s

! Warning and error tolerances
! ----------------------------------------------------------------------
  *DO,II,1,NComp
    TOLER(II, 1)= 1E-03 $ TOLER(II, 2)= 1E-03
  *ENDDO

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

Results

LabelTargetCivilFEMRatioTolerance
Sa(1)y 2.2633 2.26331.000 0.001
Sa(2)y 2.6137 2.61371.000 0.001
Sa(3)y 2.9641 2.96411.000 0.001
Sa(4)y 3.3145 3.31451.000 0.001
Sa(5)y 3.6649 3.66491.000 0.001
Sa(6)y 4.0153 4.01531.000 0.001
Sa(7)y 4.3657 4.36571.000 0.001
Sa(8)y 4.3657 4.36571.000 0.001
Sa(9)y 2.6729 2.67291.000 0.001
Sa(10)y 1.926 1.9261.000 0.001
Sa(11)y 1.5054 1.50541.000 0.001
Sa(12)y 1.2356 1.23561.000 0.001
Sa(13)y 1.0478 1.04781.000 0.001
Sa(14)y 0.90952 0.909521.000 0.001
Sa(15)y 0.18418 0.184181.000 0.001
Sa(16)y 0.076661 0.0766611.000 0.001
Sa(17)y 0.041764 0.0417641.000 0.001
Sa(18)y 0.026227 0.0262271.000 0.001
Sa(19)y 0.017986 0.0179861.000 0.001
Sa(20)y 0.013097 0.0130971.000 0.001
Sa(1)y 2.2633 2.26331.000 0.001
Sa(2)y 2.6137 2.61371.000 0.001
Sa(3)y 2.9641 2.96411.000 0.001
Sa(4)y 3.3145 3.31451.000 0.001
Sa(5)y 3.6649 3.66491.000 0.001
Sa(6)y 4.0153 4.01531.000 0.001
Sa(7)y 4.3657 4.36571.000 0.001
Sa(8)y 4.3657 4.36571.000 0.001
Sa(9)y 2.6729 2.67291.000 0.001
Sa(10)y 1.926 1.9261.000 0.001
Sa(11)y 1.5054 1.50541.000 0.001
Sa(12)y 1.2356 1.23561.000 0.001
Sa(13)y 1.0478 1.04781.000 0.001
Sa(14)y 0.9095 0.909521.000 0.001
Sa(15)y 0.1842 0.184181.000 0.001
Sa(16)y 0.0767 0.0766611.000 0.001
Sa(17)y 0.0418 0.0417641.001 0.001
Sa(18)y 0.0262 0.0262270.999 0.001
Sa(19)y 0.018 0.0179861.001 0.001
Sa(20)y 0.0131 0.0130971.000 0.001


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