SACS Extreme Wind Analysis - Spectral Response Combination

Dear Bentley Staffs,

I found something strange about the extreme wind analysis executed by SACS.

Sample 12 provided an example of extreme wind analysis by using spectral approach and automatic combined the wind extreme value with static result.

The combination process between static and extreme wind response is integrated with STCMB which suppose to be "PRSC &PRST" by default similar to response spectrum analysis.

However, I did a manual combination by using combine module which is expected to get the same result. Unfortunately, the different results are found.

The top picture is the output provided by sample 12 for DIRECTION 0 only. This is original process suggested by Bentley.

The middle picture is the result of manual combine by using "PRSC &PRST".

You can see the different in result between the top and the middle picture which is expected to be the same.

Then, I did a test run with manual combination using LIN option.

It is surprisingly found that the results from LIN option are very similar to Sample 12....which should not be....

The results from spectral analysis is positive definite. Then, we should swap the sign convention when they are combined with static result i.e. like "PRSC &PRST" option.

Can Bentley check about the combination option for extreme wind analysis with STCMB option?

Regards,

Kasiphon