Transferring load from old to new structure

[ukciv]

I'm working on a project where the existing substructure is in poor condition, but everything from the deck beams up is ok.

We are designing/installing new piles and a new steel frame to support the deck beams so the existing substructure can be removed.

Currently for the load transfer we intend to install the new structure and then 'jack up' under the existing beams to take the load before the existing substructure is removed (alternatively we may drive in & weld wedges/packers between old & new). We'll be locally strengthening the existing beams with plates above the new supports.

Its on my list to look at later this week - I was wondering whether people had any clever methods they've used for ensuring load transfer in the past, or whether there was any particular 'bear in mind' issues people would like to flag up?

Cheers.

ukciv

 

[Ron]

I prefer screw jacks as they are much more controllable than other methods.

Is there no way to remediate the substructure in place?

 

[ukciv]

Sadly not, the existing piles in particular are in a bad condition.

 

[hokie66]

Permanent or temporary flat jacks are normally at least part of the solution to preloading the new structure.

 

[Den32]

This can be complex. What type of structure is it and how many stories?

Are the 'new piles' being installed the 'temporary' foundations or 'permanent'? I assume they are the 'temporary', else why are you removing the existing foundations?

Another side note - note sure what is specifically wrong with the exsting piles - but make sure the 'Geotech' has properly spec'd the 'new' piles......is it a pile damage issue? or soil support issue? I assume the new piles will be installed close to the exsting ones. And also, if the existing ones are being removed, how does this affect the new piles (voids? effect of skin friction on adjacent piles).

My 2 cents