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Re: Caissionse

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You are right, for a 12" structural flat slab, you can design the column
strip to take the compression & tension forces required, with stirrups
and continuous rebars in the column strips.

Tom Chiu, SE
Thomas Engineering

Tom Long wrote:
> 
> To All:
> 
> We are designing a USD$400 million airport in Manila.  The foundation
> system will be caissions bored into natural bedrock is about 3m.  The
> existing ground above the bedrock has a large amount a expansive
> properties.  Therefore we are using a structural slab system for thr
> first level of a five level airport.  The distancd to the bedrock from
> level 1 varies from 1/2m to 2-1/2m.  The structural slab is a two-way
> flat plate with drop panels, the thickness of the slab is 300mm (12").
> 
> The UBC94 code is concerned, Section 1807.2,  states that we will need
> tie beams for our caisson foundation scheme. The code states that:
> 
> Individual pile caps and caissons of every structure subjected to
> seismic forces shall be interconnected by ties. Such ties shall be
> capable of resisting, in tension or compression, a minimum horizontal
> force equal to 10 percent of the larger column vertical load.
> 
> EXCEPTION: Other approved methods may be used where it can be
> demonstrated that equivalent restraint can be provided.
> 
> I think that the flat slab alone on level 1 could meet the above
> restraint requirement mentioned above? What do you think? Please comment
> on this. Does anybody have any feedback.
> 
> Best Regards
> 
> Tom Long
> PCI Asia
>