Error during cable analysis

Can any one find the solution for this

STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 9/19/2018
JOB NAME Load at 4m from center of lifting frame
JOB NO 123
JOB REV R1
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 0.740001 0 0; 3 1.74 0 0; 4 2.74001 0 0; 5 3.74001 0 0;
7 5.68001 0 0; 8 6.68001 0 0; 9 7.68002 0 0; 10 8.68002 0 0; 11 9.42002 0 0;
13 0.740001 0 8.40002; 14 1.74 0 8.40002; 15 2.74001 0 8.40002;
16 3.74001 0 8.40002; 17 5.68001 0 8.40002; 18 6.68001 0 8.40002;
19 7.68002 0 8.40002; 20 8.68002 0 8.40002; 21 0 0 8.40002;
22 9.42002 0 8.40002; 25 0.740001 0 2; 32 8.68002 0 2; 33 0 0 2;
34 9.42002 0 2; 37 0.740001 0 6.40001; 44 8.68002 0 6.40001; 45 0 0 6.40001;
46 9.42002 0 6.40001; 48 3.56001 0 2; 49 3.56001 0 6.40001; 50 5.86001 0 2;
51 5.86001 0 6.40001; 52 4.71001 0 0; 53 4.71001 0 8.40002;
56 4.43501 5.75101 0; 57 4.43501 5.75101 8.40002; 58 4.98501 5.75101 0;
59 4.98501 5.75101 8.40002;
MEMBER INCIDENCES
1 1 33; 2 33 45; 3 45 21; 4 2 1; 5 13 21; 6 25 33; 7 37 45; 8 2 3; 9 13 14;
10 25 48; 11 37 49; 12 3 4; 13 14 15; 16 4 5; 17 15 16; 18 48 50; 19 49 51;
20 5 52; 21 16 53; 22 7 8; 23 17 18; 26 8 9; 27 18 19; 28 50 32; 29 51 44;
30 9 10; 31 19 20; 32 10 11; 33 20 22; 34 32 34; 35 44 46; 36 11 34; 37 34 46;
38 46 22; 39 52 7; 40 53 17; 45 2 56; 46 10 58; 47 13 57; 48 20 59;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 1.99947e+08
POISSON 0.3
DENSITY 76.8191
ALPHA 6.5e-06
DAMP 0.03
TYPE STEEL
STRENGTH FY 248210 FU 399894 RY 1.5 RT 1.2
END DEFINE MATERIAL
CONSTANTS
MATERIAL STEEL ALL
MEMBER PROPERTY BRITISH
1 TO 13 16 TO 23 26 TO 40 TABLE ST PIP40616.0
MEMBER PROPERTY BRITISH
45 TO 48 PRIS YD 0.08
SUPPORTS
56 TO 59 PINNED
MEMBER CABLE
45 TO 48 TENSION 1
LOAD 1 LOADTYPE Dead TITLE DL
SELFWEIGHT Y -1
PERFORM CABLE ANALYSIS BASIC
CHANGE
LOAD 2 LOADTYPE Live TITLE 4M VERTICAL
MEMBER LOAD
8 9 CON GY -1200 0
30 31 CON GY -1200 1
PERFORM CABLE ANALYSIS BASIC
CHANGE
LOAD 3 LOADTYPE Live TITLE 4M HORIZONTAL
MEMBER LOAD
30 31 CON GZ -120 1
8 9 CON GZ -120 0
PERFORM CABLE ANALYSIS BASIC
CHANGE
LOAD COMB 4 COMBINATION LOAD CASE 4
1 1.1 2 1.0 3 1.0
PERFORM CABLE ANALYSIS BASIC
CHANGE
PERFORM ANALYSIS PRINT ALL
PARAMETER 1
CODE BS5950
RATIO 1 ALL
TRACK 2 ALL
CHECK CODE ALL
FINISH

This structure is buckling even under the selfweight loading. If you run a first order analysis ( PERFORM ANALYSIS with just the selfweight ) you will see large displacements in Y. So I would suggest that you first do a basic first order analysis with the loads and ensure that displacements are within reasonable limits for all cases. You will need to add lateral supports as otherwise the structure does not have any lateral stability with the frame hanging from four pinned supports and suspended using axial only cable elements. Stabilizing the structure even against vertical loads would require addition of weak lateral springs. Try adding weak translational springs in FX and FZ at four corners. If you need to analyze this structure for lateral loads, you would definitely need to have additional lateral supports besides these springs. Also for any nonlinear type analysis you will need to use REPEAT LOADs and not LOAD COMBINATIONs.

This structure is buckling even under the selfweight loading. If you run a first order analysis ( PERFORM ANALYSIS with just the selfweight ) you will see large displacements in Y. So I would suggest that you first do a basic first order analysis with the loads and ensure that displacements are within reasonable limits for all cases. You will need to add lateral supports as otherwise the structure does not have any lateral stability with the frame hanging from four pinned supports and suspended using axial only cable elements. Stabilizing the structure even against vertical loads would require addition of weak lateral springs. Try adding weak translational springs in FX and FZ at four corners. If you need to analyze this structure for lateral loads, you would definitely need to have additional lateral supports besides these springs. Also for any nonlinear type analysis you will need to use REPEAT LOADs and not LOAD COMBINATIONs.