Slab Strengthening for Compactus Loading
Slab Strengthening for Compactus Loading
(OP)
Hi guys
I have an existing reinforced concrete that I need to design for a compactus loading which exceeds the design strength of the slab.
The compactus will be position roughly midspan of the middle span of the slab (between grids 13 and 14).
The slab is one way spanning onto the beams, I have gone through and done some calculations of this slab and I am not happy with the design of the slab in general. I do not believe that it has sufficient negative moment reinforcement over the beams (for the design load prior to the compactus).
However, I need to look at methods to strengthen this slab. Firstly I think of FRP strengthening. Primarily the slab needs to be strengthened at negative moments regions of the beams, deflections won't be excessive and the slab will be covered so any additional cracking will not be visual.
What would be other strengthening methods and how would the cost compare to that of FRP strengthening.
All help will be appreciated.
I have an existing reinforced concrete that I need to design for a compactus loading which exceeds the design strength of the slab.
The compactus will be position roughly midspan of the middle span of the slab (between grids 13 and 14).
The slab is one way spanning onto the beams, I have gone through and done some calculations of this slab and I am not happy with the design of the slab in general. I do not believe that it has sufficient negative moment reinforcement over the beams (for the design load prior to the compactus).
However, I need to look at methods to strengthen this slab. Firstly I think of FRP strengthening. Primarily the slab needs to be strengthened at negative moments regions of the beams, deflections won't be excessive and the slab will be covered so any additional cracking will not be visual.
What would be other strengthening methods and how would the cost compare to that of FRP strengthening.
All help will be appreciated.






RE: Slab Strengthening for Compactus Loading
RE: Slab Strengthening for Compactus Loading
asixth - By "compactus" are referring to a trash compactor of sorts?
You don't indicate the size of the "compactus" relative to the slab's span - this might help to provide additional insight.
You say "I do not believe that it (the slab) has sufficient negative moment reinforcement over the beams (for the design load prior to the compactus)." Then you say "...the slab needs to be strengthened at negative moments regions of the beams, ..." - don't you mean slabs?
Obviously it will be least costly if you can keep all remedial work on top of the floor structure and not have to do anything to the underside.
Ralph
Structures Consulting
Northeast USA
RE: Slab Strengthening for Compactus Loading
What is the positive reo like? Can you redistribute to the bottom reo some of the loading?
If the strengthening is for the compactus and not the original possibly inadequate design, I would look at providing beams under the wheel runs. I normally like to see if they can accept a small setup into the filling system first, if not I would either put the beams under the slab, and play with the stiffness and back jacking, to get the beam to take the loading.
Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that they like it
RE: Slab Strengthening for Compactus Loading
Unsure of the type of compactus but the max loading weight is 12t (120kN/26kips).
The bottom reinforcement is okay because there is unbalanced moment from the end-spans trying to hog the middle span.
RE: Slab Strengthening for Compactus Loading
RE: Slab Strengthening for Compactus Loading
Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that they like it