Steel Grillage Raft Foundation

[Fontain]

Hi
I have beed tasked with designing grillage foundations for a series of slim towers to be used for rapid deployment telecom sites. Due to the base width of the towers, it is impossible to design isolated footings for each leg so I have to use a raft foundation. Unfortunately while there's alot of guidance for isolated grillage foundations, I have failed to find any text that offers guidance for a grillage raft foundation. Does anyone knowm of a reference I can use?

 

[r13]

Are you going to place more than one tower on the raft foundation? The design should be the same as raft supporting multiple columns. If only one tower, then it remains the same as spread footing design. I don't quite follow your concern though.

 

[jimstructures]

Fontain,

Are you talking about a concrete raft foundation with individual grillage on the raft at each column location or a large grillage foundation is located at grade supporting many slender columns?

It is not clear what you are asking questions about.

Jim

 

[HTURKAK]

I think you do not want to use concrete at the site. In general , to best my knowledge , pyramid type arrangements are used for each leg to transfer the horizontal shear to the base through truss action and compacted soil around , is not considered as bracing the leg.

Reference ; Design of latticed steel transmission structures-ASCE (2015)

The following snap from the above reference..