For my requirement , i tried for natural frequency analysis of a cantilever beam.
While analysis the model its generates the warning message, " Instability at Joint" , How does it can be rectified?
Pls. find the below the model. I would appreciate any assistance anyone could give me with this.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 09-Sep-14
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 0 0.04 0; 3 0 22 0; 4 0 11.02 0; 5 0 16.51 0; 6 0 5.53 0;
7 0 19.255 0; 8 0 13.765 0; 9 0 8.275 0; 10 0 2.785 0; 11 0 1.4125 0;
12 0 4.1575 0; 13 0 6.9025 0; 14 0 9.6475 0; 15 0 12.3925 0; 16 0 15.1375 0;
17 0 17.8825 0; 18 0 20.6275 0; 19 0 21.3138 0; 20 0 19.9412 0; 21 0 18.5687 0;
22 0 17.1963 0; 23 0 15.8237 0; 24 0 14.4513 0; 25 0 13.0788 0; 26 0 11.7063 0;
27 0 10.3337 0; 28 0 8.96125 0; 29 0 7.58875 0; 30 0 6.21625 0; 31 0 4.84375 0;
32 0 3.47125 0; 33 0 2.09875 0; 34 0 0.72625 0; 35 0 0.02 0; 36 0 0.03 0;
37 0 0.01 0;
MEMBER INCIDENCES
1 1 37; 2 2 34; 3 4 26; 4 5 22; 5 6 30; 6 7 20; 7 8 24; 8 9 28; 9 10 32;
10 11 33; 11 12 31; 12 13 29; 13 14 27; 14 15 25; 15 16 23; 16 17 21; 17 18 19;
18 19 3; 19 20 18; 20 21 7; 21 22 17; 22 23 5; 23 24 16; 24 25 8; 25 26 15;
26 27 4; 27 28 14; 28 29 9; 29 30 13; 30 31 6; 31 32 12; 32 33 10; 33 34 11;
34 35 36; 35 36 2; 36 37 35;
DEFINE MATERIAL START
ISOTROPIC STEEL1
E 2.05e+008
POISSON 0.3
DENSITY 325.3
ALPHA 1.2e-005
DAMP 0.03
ISOTROPIC STEEL
E 2.05e+008
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-005
DAMP 0.03
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
2 TO 33 PRIS AX 0.56 AZ 0.56 IX 1.30415 IY 1.30415 IZ 1.30415
1 34 TO 36 PRIS AX 14.75 AZ 14.75 IX 17.32 IY 17.32 IZ 17.32
CONSTANTS
MATERIAL STEEL1 MEMB 2 TO 33
MATERIAL STEEL MEMB 1 34 TO 36
SUPPORTS
3 FIXED
CUT OFF MODE SHAPE 20
CUT OFF FREQUENCY 10000
LOAD 1
SELFWEIGHT X -1
SELFWEIGHT Y -1
SELFWEIGHT Z -1
MODAL CALCULATION REQUESTED
PERFORM ANALYSIS
PERFORM ANALYSIS PRINT MODE SHAPES
FINISH