huangyhg

live load reduction for warehouse slab
if your slab on the ground has some stiffness and is fixed to the piles another consideration than estochastical distribution of the load intervenes, since in such in the end piled-mat piles and mat will be sharing the load.
it is typical in piled-mats to share the load in around halfs, say 40% to 60%, and the proportion even varies with time with the progressive settlement and aging of the concrete. in such case the advice of your colleague would be normally warranted even from merely a structural standpoint.
what above is merely to reckon that some loads will be passed directly to the ground through the slabs even for modest soils.
ubc 94 1606 expressly indicates that for storage areas where ll>4.79kn/m2 no ll reduction is allowed.
if some reduction is to be allowed due to the expected average allocation of the loads you should be able to ascertain of what really the project estimates the loading will be, or some code statement such that above.
argadoo (visitor)19 apr 02 13:23
thank you ishvaaag,
i have a further question, when we design flat slab,the thickness of drop panel will be about slab thickness/6. so if the flat slab is supported directly by plies, the thickness of pile cap will be slab thickness/6 or more? and how deep of pile be embedded in the slab?
argadoo
if for single piles you may add cube pile caps to widen the introduction of the forces, diminishing the punching problem.
other than that, normally you will count with just the depth of the slab aa the punching area, or the depth of the slab where it is constant. respect how much penetration is required, just enough to get bearing and leave enough cover for the bottom main rebar in the mat on the ground, say 6 to 8 cm, or the cover the specification demands.
i have practiced all that here said with in-situ augered-concreted piles with no other problem than some misplaced piles causing some additional embedded beams on the ground work.

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