Moment redistributions in RAPT 1

[Datpt]

Hi everyone,
Currently, I am using RAPT for designing beams and slabs.
I see that RAPT only allows moment redistribution for braced frames.
I think this restriction is made to prevent the redistribution of moments due to lateral loads, which can lead to the lateral instability of the frames.

What does everyone think about my explanation?
Is there any other reason for this limitation in RAPT?

Thank you so much for your discussion.

 

[rapt]

Yes, the logic is that you should not use moment redistribution in cases where the member is providing lateral stability in a sway frame.

I noticed that the old BS8110 code allows some redistribution in these cases, but reduced the maximum from 30% to 10%.

 

[Smoulder]

Is redistributing in braced frames also outlawed in As3600?

 

[rapt]

No, it is allowed.

But most times it is found to not save money on new designs as crack control normally controls and you actually can end up with more reinforcement overall.

It tends to be used more to justify existing buildings that are under strength at some sections and crack control is considered to not be an issue.

 

[Smoulder]

Thank you. I meant unbraced frames but think you understood.