Moment Curvature - Rotation

Hi,

After section analysis two values are obtained, (yield and ultimate) so a bi-linear relationship is formed. Now, i want to consider strength degradation "IDUCT" so I have to use Fardis & EC8 equations to get the following limit states "yield, maximum, near collapse", but the problem is all these are in rotations and Ruaumoko only use curvatures.

How to calculate curvature ductility (IDUCT2 and IDUCT3)

Thanks.

I am not too sure to which equations of EC8 you are referring to.. However, in case they give express limit states in terms of PLASTIC rotations (such as the american codes FEMA 356, ASCE 41, etc.) you can work out plastic curvature limits as plastic rotation divided by plastic hinge length (you'll have to work out your best estimate of plastic hinge length). Then the ductility will be plastic curv/yield curv + 1. You have the yield curvature from your sectional analysis.

Cheers,

Dom

Thanks Domenico, another issue related to hinge length,

In Member hinge length, please correct me if I'm wrong, "H1&H2 is about z-z and H3&H4 is about y-y" are those hinge length are used because Ruaumoko doesn't know member geometrical properties like depth and width, because we have to input the final properties like A, I, J, ... etc. Therefore, for a rectangular section H1,H2 & H3,H4 could simply be (H/2 for y-y & B/2 for z-z).

I'm little confused! because i know that hinge length for line elements should be in the local x-x direction only.

Thanks again!

@ Domenico

Could do please explain this equation or the source of it (ductility will be plastic curv/yield curv + 1)?

tot/yield=(yield+plastic)/yield=1+plastic/yield