×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Live load reduction for warehouse slab

Live load reduction for warehouse slab

Live load reduction for warehouse slab

(OP)
Hi,
        I'm working on the warehouse slab design which live load 5t/sq.m.  Due to the soil condition is not good, I decide to use piles to transmit load from slab to the good soil below and I designed the floor slab as flat slab. I got the suggestion from my senior colleague that when we design the floor slab we use 100% of live load (5t/sq.m.) but when we calculate the load on pile, we use only 75% of live load (3.75t/sq.m.). He said from statistic the warehouse has never been used their full live load so we can reduce the live load. But I think it's not consistent for the slab design and load on pile calculation. Where can I find the code or reference for this reduction or you guy has any sugeestion?
Thanks,
Argadoo

RE: 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.


RE: Live load reduction for warehouse slab

(OP)
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

RE: Live load reduction for warehouse slab

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources