difference on analysis occured in V14 and V8

[cprr0107]

V14 vs. V8

1.)
I modeled a simple howe truss in SAP V.14 and compared it with SAP V.8.

i only have released the moments(M2&M3) for the diagonal and vertical members of the truss, having my top and bottom cord with no moment releases.

SAP v. 8 analysis results does not show any WARNINGS.
but SAP v.14 has warnings using the standard solver.

the warning in SAP v 14 goes something like this:

"
B E G I N A N A L Y S I S 2010/08/18 18:25:13


RUNNING ANALYSIS WITHIN THE GUI PROCESS
USING THE STANDARD SOLVER (PROVIDES COMPLETE INSTABILITY INFORMATION)


E L E M E N T F O R M A T I O N 18:25:13



L I N E A R E Q U A T I O N S O L U T I O N 18:25:13

FORMING STIFFNESS AT ZERO (UNSTRESSED) INITIAL CONDITIONS

TOTAL NUMBER OF EQUILIBRIUM EQUATIONS = 63
APPROXIMATE "EFFECTIVE" BAND WIDTH = 15

NUMBER OF EQUATION STORAGE BLOCKS = 1
MAXIMUM BLOCK SIZE (8-BYTE TERMS) = 862
SIZE OF STIFFNESS FILE(S) (BYTES) = 6.996 KB

NUMBER OF EQUATIONS TO SOLVE = 63

* * * W A R N I N G * * *
NUMERICAL PROBLEMS ENCOUNTERED DURING EQUATION ASSEMBLY:

TYPE LABEL DOF X-COORD Y-COORD Z-COORD PROBLEM VALUE
----- ------- -- ----------- ----------- ----------- ------------- -----------
Joint 7 RX -2.666667 .000000 .000000 Diag = 0 --> 1.00E-10
Joint 8 RX -1.333333 .000000 .000000 Diag = 0 --> 1.00E-10
Joint 6 RX .000000 .000000 .000000 Diag = 0 --> 1.00E-10
Joint 9 RX 1.333333 .000000 .000000 Diag = 0 --> 1.00E-10
Joint 10 RX 2.666667 .000000 .000000 Diag = 0 --> 1.00E-10

* * * W A R N I N G * * *
NUMERICAL PROBLEMS ENCOUNTERED DURING EQUATION SOLUTION:

TYPE LABEL DOF X-COORD Y-COORD Z-COORD PROBLEM VALUE
----- ------- -- ----------- ----------- ----------- ------------- -----------
Joint 15 RZ -2.666667 .000000 1.000000 Lost accuracy 15.5 digits
Joint 16 RZ -1.333333 .000000 2.000000 Lost accuracy 15.8 digits
Joint 17 RZ 1.333333 .000000 2.000000 Lost accuracy 15.8 digits
Joint 18 RZ 2.666667 .000000 1.000000 Lost accuracy 15.3 digits

* * * W A R N I N G * * *
EXCESSIVE LOSS OF ACCURACY WAS DETECTED DURING THE SOLUTION OF EQUATIONS
NUMBER OF DIGITS LOST EXCEEDED 11.0


* * * W A R N I N G * * *
THE STRUCTURE IS UNSTABLE OR ILL-CONDITIONED !!
CHECK THE STRUCTURE CAREFULLY FOR:
- INADEQUATE SUPPORT CONDITIONS, OR
- ONE OR MORE INTERNAL MECHANISMS, OR
- ZERO OR NEGATIVE STIFFNESS PROPERTIES, OR
- EXTREMELY LARGE STIFFNESS PROPERTIES, OR
- BUCKLING DUE TO P-DELTA OR GEOMETRIC NONLINEARITY, OR
- A FREQUENCY SHIFT (IF ANY) ONTO A NATURAL FREQUENCY


NUMBER OF EIGENVALUES BELOW SHIFT = 0


L I N E A R S T A T I C C A S E S 18:25:13

USING STIFFNESS AT ZERO (UNSTRESSED) INITIAL CONDITIONS

TOTAL NUMBER OF CASES TO SOLVE = 1
NUMBER OF CASES TO SOLVE PER BLOCK = 1

LINEAR STATIC CASES TO BE SOLVED:

CASE: DEAD


A N A L Y S I S C O M P L E T E 2010/08/18 18:25:13"

Does how does this differ?is SAP v.14 CORRECT?
you can model it on your own.

2.)
and i have used also the multi-threaded solver and deleted the supports for this type of truss and runned the program for analysis. but SAP14 shows "NO" warnings. how does this happen?

please help.
thanks a lot in advance!!

cprr0107