Would you please explain the External Restraint to shrinkage? In the past the default/recommendation was 10-20%. In Version 8 Updated 2, The default is 0% and is appropriate for a typical intermediate floor in a multi-story structure. Could you explain the reason for the change? Have there been adjustments to the calculation or a change in the effect of the external restraint? Thank you.
Prior to Version 8 Update 2, the default was 20% in all models. A percentage that high is not appropriate for most cases and led to overly conservative long-term predictions. The actual calculation of shrinkage effects due to the external shrinkage restraint % has not changed from previous versions.
When the external shrinkage restraint % was introduced several versions back, the intent was for users to use engineering judgement and decide on an appropriate value for the structure that they were designing. See comments from Jonathan H. in this forum for more discussion on that and also more information on how the shrinkage restraint percentage is used by RAM Concept. Many RAM Concept users, however, were using the default and not changing the value. The end result was deflections that were significantly higher than the results obtained in other software. One example of such a comparison and a conservative result due to shrinkage restraint is discussed in this forum.
Thank you very much for the quick reply. This answers my questions and provide some background.