Dear All,
I have analyze the model in 3d staad. it is giving me following warning
***WARNING - INSTABILITY AT JOINT 114 DIRECTION = MX
PROBABLE CAUSE SINGULAR-ADDING WEAK SPRING
K-MATRIX DIAG= 1.0838102E+04 L-MATRIX DIAG= -3.0140654E-09 EQN NO 790
***NOTE - VERY WEAK SPRING ADDED FOR STABILITY
**NOTE** STAAD DETECTS INSTABILITIES AS EXCESSIVE LOSS OF SIGNIFICANT DIGITS
DURING DECOMPOSITION. WHEN A DECOMPOSED DIAGONAL IS LESS THAN THE
BUILT-IN REDUCTION FACTOR TIMES THE ORIGINAL STIFFNESS MATRIX DIAGONAL,
STAAD PRINTS A SINGULARITY NOTICE. THE BUILT-IN REDUCTION FACTOR
IS 1.000E-09
THE ABOVE CONDITIONS COULD ALSO BE CAUSED BY VERY STIFF OR VERY WEAK
ELEMENTS AS WELL AS TRUE SINGULARITIES.
I have tried all the options which is mentioned in all previous posts. kindly help me to resolve all warnings. I have attaching the staad file for more information. JS-0103-3D-LSM--FINAL.std
You have used the following commands to define member truss in the model:MEMBER TRUSS 122 127 132 137 142 147 152 157 162 167 260 TO 269 294 297 TO 306 331 334 -335 TO 353
Instead of this use 99% partial moment release:
MEMBER RELEASE122 127 132 137 142 147 152 157 162 167 260 TO 269 294 297 TO 306 331 334 -335 TO 353 BOTH MP 0.99
You have MEMBER TENSION specification in the model and you need to use REPEAT load instead of load combination. You have the following commands:
LOAD COMB 101 DEAD + LIVE
5 1.5 7 1.5
Change them to :
LOAD 101 DEAD + LIVE
REPEAT LOAD
7522.JS-0103-3D-LSM--FINAL.std