CANTILEVER DEFLECTION 1

[PSR_1]

Am using RAM to perform LT deflection check. The attached picture is from part of the slab and it shows cantilever. The red boxes are columns. What is bugging me is that am getting the deflection to be in the direction of section 2-2 than the cantilever falling in the direction of section 1-1. Is that possible or am I making any mistake?

Column center to center is 7.5 meters.

 

[hardbutmild]

I'm not entirely sure what exactly do you mean when you say LT, but I guess it's a regular horizontal plate loaded out of plane (vertical loads).

This makes sense to me, since the area close to the column is stiffer than the area between the columns. I drew a picture to show it.

You can think of it the same way that you'd think about reinforcement layout, there'll be more reinforcement closer to the columns (we call it columns strip, versus the middle strip between the columns).

 

[PSR_1]

Thanks hardbutmild, I mean long term by LT. And u are describing what my slab is experiencing exactly.

 

[hardbutmild]

Yeah, this doesn't really have anything to do with long term, it has to do with how the flat plate works. I drew another picture to try and explain it.

Also, when I say frame action I don't necessarily mean that significant bending moment transfer occurs, just that those parts of plate are directly supported and provide a flexible support for the rest of the plate.

 

[PSR_1]

I think I got it now. thanks again hardbutmild!

 

[Enhineyero]

To put this in simpler terms, the deflection of the plate within the line of columns (direction 2-2) contributes to deflection on the cantilever (direction 1-1).

If you measure the deflection on direction 1-1 on the middle column, the cantilever deflection is around 6mm, deflection directly at the column is 0mm.

Moving further on towards the right hand side at the mid-point between column, again on direction 1-1, deflection at cantilever is around 21mm and deflection at line of columns is around 15mm (21mm-15mm= 6mm) this shows you that 15mm of the cantilever deflection comes from the support, the pure cantilever deflection, 6mm, matches the deflection above. That makes sense to me.