Connecting the Piles to Raft & Spring Constant

[bdbd]

Hello everyone,

My question is about spring constants. I know lately, a lot of discussion is going on about spring constant in this forum, but I have somehow different question.

For example, in site, after piles are constructed, they connect it to raft with reinforcements. It is the common process.

However, geotechnical engineer gives structural engineer a spring constant for pile and structural engineer calculates the system that way. Now, in spring model, spring acts only to axial load. I mean it does not carry bending moment or shear. Thus, pile in structural model does not carry too.

This means pile is hinged to raft, not fixed. But when we connect piles to raft with reinforcements, we are fixing it to the raft. Thus, pile is carrying moment.

My question is, assume that there is no soil between pile and raft, or effect of this soil is not important, is it okay to not connecting piles to raft in site, because structural engineer checks the system and says it is ok.

Because, s/he says that piles are okay with hinged connection to raft, so why the people in site should connect these to raft?

 

[KootK]

My question is, assume that there is no soil between pile and raft, or effect of this soil is not important, is it okay to not connecting piles to raft in site, because structural engineer checks the system and says it is ok.

Theoretically , yes; practically, no.

Because, s/he says that piles are okay with hinged connection to raft, so why the people in site should connect these to raft?

Because, in general, we structural engineers think that it's best to tie things together. Theoretically, it is not always necessary to tie columns into supporting footings. Would I ever actually do that? Not a chance.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.