Horizontal Base Shear on a Piled Raft Footing for a Building??

[gmannix1000]

Hi All,


I have a building above grade (no basement) that is piled, three cores so no stability issues. Each core is on a piled raft foundation and takes roughly 1000kN base shear at the raft.

My question is, how do I take the horizontal shear from the lateral loads out on this, each pile has little horizontal load capacity (say 40kN/pile) and probably 15 piles/raft. Can I say that the cores are tied to the ground floor and for horizontal base shear force is transmitted through the ground floor slab to ALL the piles in the building (roughly 150 piles total) or how is this typically designed out?

Friction between base of raft foundation slab/ground floor slab and subgrade ever come into play or should this be ignored?

Thanks in advance.

 

[slickdeals]

There's a few ways to do this.
1. Check the passive resistance of the pile cap, based on the width and depth of the pile cap
2. Use grade beams to push the load out to adjacent piles/pile groups. You can use slab on grade as a structural diaphragm to do this as well, but I would be cautious doing it depending on what the usage of the 1st level is. There is a good chance that these slabs could be ripped out etc. if it's a retail space.

What are your seismic design parameters?