Seismic design of timber structure with steel braces

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Hi, I have a timber post and beam structure with steel braces (tension only) in both X and Y directions. There is also one wall as beam panel and one CLT wall. I need to perform a response spectrum analysis. I have already set up modal analysis where I deactivated steel braces in compression (half of them in both directions). Then I have set up a seismic load case, then a seismic design situation, everything as in webinars I found online.

Is it possible to create several load cases based on several modal analyses where different tension braces are deactivated based on direction, and then combine them in design situation? Would that make sense? I’m not sure how to properly consider tension braces in seismic design.

Another question is when I perform Timber Design I get a warning: lines will not be calculated for loading with envelope results. What does that mean?

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Hi wolfram,

First of all, it’s worth checking whether nonlinear effects really need to be considered in the response spectrum analysis, or if a linear approach would already be sufficient.

In the following Knowledge Base article, you’ll find how structural modifications or the use of pre-deformations can be applied to simulate the failure of tension members: Using Nonlinearities in Response Spectrum Analysis in RFEM 6

:globe_showing_europe_africa: Combination of Earthquake Load Cases

It is generally possible to combine multiple earthquake load cases within one design situation (DS). However, please note:

For each involved load case (LC) or load combination (CO) individual structural modifications must be defined to properly simulate the failure of tension members.

You can find more details here:

:wood:Timber Design – Error Message

To analyse the problem more precisely, the model file would be very helpful:

:right_arrow: Click on File → Save as and choose the following settings to reduce the file size:

image
image467×393 7.53 KB

:right_arrow: Then upload the file here (e.g. *.rf6, *.rs9) – this way, the community can also contribute to the solution.

:owl: Prefer not to share the file publicly? No problem – send it to me via direct message: click on my profile picture or user name → Message.

Best regards
Marco Nikoleizig