section deformation

[liujinlong]

hi everyone, i have a question about the fiber section deformation of a RC column, when the column subject to a axial force and a moment, the steel in the tension side is yield, but in compression side the steel and the concrete is in elastic still. at this state reduce the moment to zero but the axial force is invariable, i am puzzled whether the tension steel have residual strain? and the plane cross-section assumption is ever on work now?

[jwaugh]

Okay, the tension steel will have some residual strain, use a stress-strain recorder to confirm this. But if you take it back to zero displacement you will see the column has some displacement when it passes through zero force.

Plane sections remain plane is in effect through ALL stages of the analysis. As long as you are using a fiber section this is true, it is how the program is calculating strains from curvatures.

[lish hit]

hi everyone, i have a question about the fiber section deformation of a RC column, when the column subject to a axial force and a moment, the steel in the tension side is yield, but in compression side the steel and the concrete is in elastic still. at this state reduce the moment to zero but the axial force is invariable, i am puzzled whether the tension steel have residual strain? and the plane cross-section assumption is ever on work now?

This is the same question that confusing me for a long time. I hope someone known it!