CFVR4201 - GB50011: Seismic Analysis X-axis

Seismic Analysis on a 1 DOF beam according to GB 50011

This example compares spectrum accelerations given by CivilFEM to accelerations obtained when solving on a 1 DOF beam and to the correct GB 50011 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

GB 50011

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: CFVR4201.DAT

   FINISH
  ~CFCLEAR,,1
  NomFile='CFVR4201'
  /TITLE, %NomFile%, GB50011: Seismic Analysis X-axis

! ----------------------------------------------------------------------
! Model definition
! ----------------------------------------------------------------------
! CivilFEM Setup: Code & Units
  ~UNITS,,LENG,CM
  ~UNITS,,TIME,S
  ~UNITS,,FORC,KP
  ~CODESEL,,,,,GB50011
/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,0.15,FREC,I,1,0.05,0.7

  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%)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

 ! 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,,ARG1,1  ! Y components of frequent horizontal spectrum
   ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,1  ! Y components of frequent 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) = 16.47
  VALUE(39,1) = 20.20
  VALUE(38,1) = 23.93
  VALUE(37,1) = 27.66
  VALUE(36,1) = 31.46
  VALUE(35,1) = 36.56
  VALUE(34,1) = 43.80
  VALUE(33,1) = 54.91
  VALUE(32,1) = 74.33
  VALUE(31,1) = 117.7
  VALUE(30,1) = 117.7
  VALUE(29,1) = 111.2
  VALUE(28,1) = 104.8
  VALUE(27,1) = 98.30
  VALUE(26,1) = 91.82
  VALUE(25,1) = 85.35
  VALUE(24,1) = 78.87
  VALUE(23,1) = 72.40
  VALUE(22,1) = 65.92
  VALUE(21,1) = 59.45

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

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

Results

Label	Target	CivilFEM	Ratio	Tolerance
Sa(1)x	59.449	59.449	1.000	1
Sa(2)x	65.923	65.923	1.000	1
Sa(3)x	72.398	72.398	1.000	1
Sa(4)x	78.872	78.872	1.000	1
Sa(5)x	85.347	85.347	1.000	1
Sa(6)x	91.822	91.822	1.000	1
Sa(7)x	98.296	98.296	1.000	1
Sa(8)x	104.77	104.77	1.000	1
Sa(9)x	111.25	111.25	1.000	1
Sa(10)x	117.72	117.72	1.000	1
Sa(11)x	117.72	117.72	1.000	1
Sa(12)x	74.334	74.334	1.000	1
Sa(13)x	54.913	54.912	1.000	1
Sa(14)x	43.797	43.797	1.000	1
Sa(15)x	36.56	36.56	1.000	1
Sa(16)x	31.457	31.456	1.000	1
Sa(17)x	27.655	27.655	1.000	1
Sa(18)x	23.927	23.927	1.000	1
Sa(19)x	20.2	20.2	1.000	1
Sa(20)x	16.472	16.472	1.000	1
Sa(1)x	59.45	59.449	1.000	1
Sa(2)x	65.92	65.923	1.000	1
Sa(3)x	72.4	72.398	1.000	1
Sa(4)x	78.87	78.872	1.000	1
Sa(5)x	85.35	85.347	1.000	1
Sa(6)x	91.82	91.822	1.000	1
Sa(7)x	98.3	98.296	1.000	1
Sa(8)x	104.8	104.77	1.000	1
Sa(9)x	111.2	111.25	1.000	1
Sa(10)x	117.7	117.72	1.000	1
Sa(11)x	117.7	117.72	1.000	1
Sa(12)x	74.33	74.334	1.000	1
Sa(13)x	54.91	54.912	1.000	1
Sa(14)x	43.8	43.797	1.000	1
Sa(15)x	36.56	36.56	1.000	1
Sa(16)x	31.46	31.456	1.000	1
Sa(17)x	27.66	27.655	1.000	1
Sa(18)x	23.93	23.927	1.000	1
Sa(19)x	20.2	20.2	1.000	1
Sa(20)x	16.47	16.472	1.000	1

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CivilFEM Online Help

CFVR4201 - GB50011: Seismic Analysis X-axis

Seismic Analysis on a 1 DOF beam according to GB 50011

Results