Moment redistribution

[GalileoG]

Hello all,

I was surprised to learn today that the Canadian Code allows for up to 20% of moment redistribution from a negative region to a positive region AND from a positive region to a negative region.

My questions are:

1. What is the rationale behind moment redistribution? Why does the code permit it?

2. When would you want to utilize moment redistribution? When would it be beneficial? When is it frowned upon?

Thanks!

 

[youngstructural]

This has been discussed in length in previous threads. Use the Google search feature.

B.Eng (Carleton)
Working in New Zealand, thinking of my snow covered home...

 

[asixth]

The Australian code allows 30% moment redistribution.

1. Moment redistribution allows for the reducancy in reinforced concrete frames and accounts for the fact that "moment redistribution" will occur before failure.

2. I would redistribute negative moment to positive moment regions. It is unacceptable to use moment redistribution for statically determinate structures such as cantilevers.

 

[statiker]

hi,

do you speak of steel structures ?

if the load is increased,
plastic hinges may occur at the most stressed area for example at the middle supports of an continuous beam.

further increases are possible because in midspan the
plastic moment is not yet reached.

if there is also a plastic hinge at midspan,
the system collapses because it is kinematic.