RAM SS - Response Spectrum Analysis according to AS1170.4

Also, it seems that shear distribution along the building is in different directions! See below:

Regarding the scale factor, what we usually tell people to do is scale the dynamic load by Ie/ R, then check the base shear and compare to the lower bound limit of .85* ELF approach, and re-scale if the dyn result is too low.

communities.bentley.com/.../ramss-dynamic-modal-analysis-faq.aspx

If only the dynamic loads show shear reversal (and static shears are as expected), then it's probably an issue of sign. There is an option to have the program consider sign in rsp analysis, which is based on the dominant mode, but it's sometimes simper just to ignore sign. If the shears are reversing for the static loads too, then that's another matter. 

Seth, could you respond to my query on 06/05/2016

I asked around but not many of us have experience with the Australian code for dynamic response spectrum analysis. Here are some comments from one of my colleagues:

[Regarding] AS 1170.4 Response Spectra load case in RAM Frame, I believe it should be generating the required level of design forces. AS 1170.4 does not have any discussion about scaling the results, so I assume it shouldn’t be necessary or appropriate. I can’t find any reference to the 0.85 factor to correlation between dynamic and static shear [though that concept is used in ASCE 7].

As noted the X +E case produced force in both the X and Y axis. That is not unusual. From the screen grab of the model it is apparent that this structure is very “dynamic”; no symmetry, abrupt changes in stiffness (longer walls are supported on shorter walls, walls that terminate at lower levels, etc.) This would also contribute to wall forces that are quite different from those produced by the static load cases.

That the story forces changed directions is an indication that the response by the structure is not primarily 1st mode, that the other modes are having a big impact on the response (this can be substantiated by looking at the Periods and Modes report).

Seth,

If RAM SS is capable of doing dynamic analysis according to Australian Standards then we expect to see clear procedure outlining scaling (I/R - refer my previous post) and any other adjustments of the software are specified.

Can you advise when it will be updated in the software and procedures explained?

In the Ram Frame analysis manual (RamFrameAnalysis.pdf), in section 5.3.9 AS 1170.4-2007 we cover how the program has implemented the Response Spectra analysis for that code (and also how the equivalent static lateral force method is performed). The information there seems to match whet is in AS 1170.4-2007 Section 7 - DYNAMIC ANALYSIS. I don't see anything about scaling the dynamic analysis results in the code, so it probably should not be done. 

Thanks Seth.
There is no scaling in AS1170.4 - based on that I believe the scaling in ram SS shall be = 1

Thanks Seth.
There is no scaling in AS1170.4 - based on that I believe the scaling in ram SS shall be = 1