Moment vs rigid zone 1

[dccd]

https://teklastructuraldesigner.sup...2_-_pin_ended_beam.htm#XREF_60955_Rigid_Zones

Why for pinned end continuous beams subjected to UDL, the sagging moment tend to decreases when rigid zone is applied ?

My thought is when rigid zone = 0 applied, no part of the beam assumed to rigid, the stiffness of beam is still similar to beam when no rigid zone applied. It’s just that when rigid zone = 0 applied, moment was taken at the column face, hence moment at the column face is generally smaller than moment taken at the center node.


Since stiffness of beam is not affected, why the sagging moment is lower when rigid zone = 0 applied?

 

[Celt83]

the page you linked to explains why, the hinge location offsets to the end of the link.

My Personal Open Source Structural Applications:

https://github.com/buddyd16/Structural-Engineering

Open Source Structural GitHub Group:

https://github.com/open-struct-engineer

 

[dccd]

the hinge location offsets to the end of the link.

I just don't understand why the hinge location offsets to the end of the link, moment will decrease

 

[BAretired]

I don't quite understand it either. The central reaction is not a concentrated load. It spreads out over the width of the support, which is deemed a "rigid zone". In that way, it reduces the effective span of the beam, which reduces the moments, both positive and negative.

The exterior supports are a different matter. If there is no continuity at the exterior support, there seems to be no justification for saying that the hinge moves to the edge of the "rigid zone". But if that is the case, the support would need to be reinforced for the eccentric moment. If the exterior supports are a wall, it would be normal practice to consider the hinge to be located at the center of the wall.

If the exterior supports are columns, the moment would more likely be in the order of wL²/24 and top bars would be needed in the beam and developed into the column. Also the inflection point would be further into the span.

I find the article fails to provide a clear understanding of the author's intent.

BA

 

[dccd]

It spreads out over the width of the support, which is deemed a "rigid zone". In that way, it reduces the effective span of the beam, which reduces the moments, both positive and negative.

Thanks for the point