CFVR4806 - UBC 97: Seismic Analysis (design spectrum) Z-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: |
|
| 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: CFVR4806.DAT
FINISH ~CFCLEAR,,1 NomFile='CFVR4806' /TITLE, %NomFile%, UBC 97: Seismic Analysis (design spectrum) Z-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 ! Spectrum definition ~DEFSPEC,ALL,4,A,DESIGN,A,7.5,2/3 pi=3.141592654 ! ---------------------------------------------------------------------- ! DATA CHECK ! ---------------------------------------------------------------------- ! Data comparision 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,,ARG1,1 ! 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 ! 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,,ARG1,1 ! Y components of design horizontal spectrum ~CFGET,VALUE(40-ARG1+1,2),SEISM,,SPEC,SDH,,ARG1,1 ! 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)= 172.65600 VALUE(39,1)= 189.50049 VALUE(38,1)= 209.98703 VALUE(37,1)= 235.44000 VALUE(36,1)= 267.91448 VALUE(35,1)= 310.78080 VALUE(34,1)= 369.97714 VALUE(33,1)= 457.03059 VALUE(32,1)= 597.65538 VALUE(31,1)= 863.28000 VALUE(30,1)= 863.28001 VALUE(29,1)= 811.48321 VALUE(28,1)= 759.68641 VALUE(27,1)= 707.88961 VALUE(26,1)= 656.09281 VALUE(25,1)= 604.29600 VALUE(24,1)= 552.49920 VALUE(23,1)= 500.70240 VALUE(22,1)= 448.90560 VALUE(21,1)= 397.10880 ! Warning and error tolerances ! ---------------------------------------------------------------------- *DO,II,1,NComp TOLER(II, 1)= 0.1 $ TOLER(II, 2)= 0.1 *ENDDO ! ---------------------------------------------------------------------- ! Results Comparison ! ---------------------------------------------------------------------- COMPARA.MAC |
Results
| Label | Target | CivilFEM | Ratio | Tolerance |
| Sa(1)z | 397.11 | 397.11 | 1.000 | 0.1 |
| Sa(2)z | 448.91 | 448.91 | 1.000 | 0.1 |
| Sa(3)z | 500.7 | 500.7 | 1.000 | 0.1 |
| Sa(4)z | 552.5 | 552.5 | 1.000 | 0.1 |
| Sa(5)z | 604.3 | 604.3 | 1.000 | 0.1 |
| Sa(6)z | 656.09 | 656.09 | 1.000 | 0.1 |
| Sa(7)z | 707.89 | 707.89 | 1.000 | 0.1 |
| Sa(8)z | 759.69 | 759.69 | 1.000 | 0.1 |
| Sa(9)z | 811.48 | 811.48 | 1.000 | 0.1 |
| Sa(10)z | 863.28 | 863.28 | 1.000 | 0.1 |
| Sa(11)z | 863.28 | 863.28 | 1.000 | 0.1 |
| Sa(12)z | 597.66 | 597.66 | 1.000 | 0.1 |
| Sa(13)z | 457.03 | 457.03 | 1.000 | 0.1 |
| Sa(14)z | 369.98 | 369.98 | 1.000 | 0.1 |
| Sa(15)z | 310.78 | 310.78 | 1.000 | 0.1 |
| Sa(16)z | 267.91 | 267.91 | 1.000 | 0.1 |
| Sa(17)z | 235.44 | 235.44 | 1.000 | 0.1 |
| Sa(18)z | 209.99 | 209.99 | 1.000 | 0.1 |
| Sa(19)z | 189.5 | 189.5 | 1.000 | 0.1 |
| Sa(20)z | 172.66 | 172.66 | 1.000 | 0.1 |
| Sa(1)z | 397.11 | 397.11 | 1.000 | 0.1 |
| Sa(2)z | 448.91 | 448.91 | 1.000 | 0.1 |
| Sa(3)z | 500.7 | 500.7 | 1.000 | 0.1 |
| Sa(4)z | 552.5 | 552.5 | 1.000 | 0.1 |
| Sa(5)z | 604.3 | 604.3 | 1.000 | 0.1 |
| Sa(6)z | 656.09 | 656.09 | 1.000 | 0.1 |
| Sa(7)z | 707.89 | 707.89 | 1.000 | 0.1 |
| Sa(8)z | 759.69 | 759.69 | 1.000 | 0.1 |
| Sa(9)z | 811.48 | 811.48 | 1.000 | 0.1 |
| Sa(10)z | 863.28 | 863.28 | 1.000 | 0.1 |
| Sa(11)z | 863.28 | 863.28 | 1.000 | 0.1 |
| Sa(12)z | 597.66 | 597.66 | 1.000 | 0.1 |
| Sa(13)z | 457.03 | 457.03 | 1.000 | 0.1 |
| Sa(14)z | 369.98 | 369.98 | 1.000 | 0.1 |
| Sa(15)z | 310.78 | 310.78 | 1.000 | 0.1 |
| Sa(16)z | 267.91 | 267.91 | 1.000 | 0.1 |
| Sa(17)z | 235.44 | 235.44 | 1.000 | 0.1 |
| Sa(18)z | 209.99 | 209.99 | 1.000 | 0.1 |
| Sa(19)z | 189.5 | 189.5 | 1.000 | 0.1 |
| Sa(20)z | 172.66 | 172.66 | 1.000 | 0.1 |
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