Prior to the B31.3-2012 introduction of the sustained stress equation, there were differing opinions on the application of the SIF in this sustained stress – apply the SIF, ignore the SIF, or use 0.75 times the SIF. Users specified their choice through a configuration file setting – Set Sustained SIF Multiplier. The CAESAR II default was to apply the full SIF with an entry of 1.0 for this configuration setting.
The sustained stress equation in the 2012 Edition of B31.3 defines the moment multiplier as 0.75 times the SIF. Accordingly, the configuration file setting was altered to reflect this change, but the configuration file setting saved during the program installation, is incorrectly stored as 1.0. This means that sustained stresses apply a fully intensified moment rather than applying three quarters of the SIF to the bending moments. In this situation, the CAESAR II calculated sustained stresses are overly conservative.
The correction described on Intergraph’s Smart Support (https://smartsupport.intergraph.com) will correct this error. It is necessary to repair the configuration file (CAESAR.CFG) in each folder where CAESAR II 2014 has been executed AND in the program’s SYSTEM directory. After making this change and rerunning models that were reported as overstressed, results may now show that there is no sustained stress problem. Keep in mind also, that a higher sustained stress will reduce the (Equation 1b) allowed stress range for expansion loads.