Ground Beam (Concrete encased steel)

[murphyabu]

Good morning,

I am just finishing the last of the groundworks for a rear extension. This last stretch requires the installation of a concrete encased universal column to bridge between two padstones (to save excavating down to 2m in medium heave clay).

All appropriate calcs and drawings have been done by my structural engineer however I'm lacking some detail around the practical installation of the steel UC.

The detail shows 155mm celcore beneath the steel, how would you effectively lift the steel above the celcore and suspend it in a manner that won't make it collapse into the cellcore?

I need to speak to the structural engineer about how the steel will interface with the padstone to be poured at the 'southern' end of the steel to ensure their is sufficient support but thought I'd avoid one SFQ by asking you guys N gals for some insight.

Thanks

 

[^woody^]

The beam is supported within the cage, which in turn is either supported off spacers or suspended on wire, off timber above the concrete level.

The reference to bearing is on to (well, should be in to) the pad [foundation] not a padstone.

 

[murphyabu]

Sound, so either
- suspend with wire from above, (I can knock up some wooden trestles to hang it from), or
- sit the wire mesh frame on those plastic foot spacers

My only concern is those plastic spacers could puncture through the cellcore with all that weight (even if we'll distributed).

Sorry my reference to padstone was intended to mean the new concrete to be poured at either end of the steel.

I'll speak to the engineer about how the steel in the ground beam should interface with the existing foundation, while I hate over engineering something just a few h10 resin bars seems odd, but I admit, I'm not the engineer!

 

[murphyabu]

After some more advice please,
I'm pouting concrete Tuesday, I've the steel in, mesh and all approved by building control.

The finished concrete level (ground beam and footings) will be 600 below DPC, but the other end of the groundbeam will be higher (height of existing slab).

I've made up the formwork etc but want to make sure the concrete which is to be finished at the higher level doesn't keep flowing down out the other end of the formwork, is there a way to prevent that from happening?

I've put a lid on part of the ground beam but don't know if I should encase more of it.......

Any pointers, thanks

 

[phatboy]

I had no issues at all doing stepped foundations, it just sat in the correct place. This was with delivered C35 mix

The guys said they could just pump a little bit against the wood stop-end first, and while it set a bit, work on other areas, then return to do the area above.