AD.2007-09.3.6* ABS/SRSS Combination
A modification to the ABS (Absolute value) and SRSS (square root sum of the squares) results combinations methods.
Additional processing is now used so the resulting combination of results contain appropriate sign/direction as is required when used for design or code checking when used with the ASME NF or AISC 360 05/10 codes.
To instruct the analysis and design engine to automatically generate these load combinations for ABS or SRSS combinations, either:
use the new, optional GENERATE parameter in the LOAD COMBINATION command, orNote: Refer to TR.35 Load Combination Specification for additional information.
select the Generate Combination option in the Define Load Combinations dialog.
All of the permutations of positive or negative sign effects in each DOF (degree of freedom) are now considered by the analysis engine. That is, in each of the 6 DOF, both positive and negative sign are considered which results in 64 possible cases (i.e, 26). As a result of this, the SRSS and ABS combinations are now presented as load envelopes (i.e., maximum and minimum values) at each member end. This is reflected in both reports and post-processing mode tables. Similarly, in the structure view in the post-processing mode, the force diagrams are now displayed graphically as an envelope rather than a single curve.
Output from the following commands displays pairs of results rows for a load at a joint (marked by an asterisk in the output):
PRINT SUPPORT REACTION
PRINT MEMBER FORCE
PRINT SECTION FORCE
PRINT PMEMB FORCE
PRINT MEMBER STRESS