My brother concreteok,
I think this cases could be your thesis or disertation on your future study.. :idea:
To prove your engineering judgement , take a deep beam theory/assumption for deep basement wall.
In my experience, I use Deep beam approach if I have problem for wall that have same condition as shown as laboratory Deep Beam test..
regards,
Robert Sasmita
Robertsas,
So how to u reckon we should do if we have a deep basement wall spanning between foundation piles? Closer supporting piles? or put up another beam below the wall to span?
(07-21-2009, 01:20 AM)concreteok Wrote: [ -> ]Robertsas,
So how to u reckon we should do if we have a deep basement wall spanning between foundation piles? Closer supporting piles? or put up another beam below the wall to span?
Dear Concreteok,
Usually, I design the basement wall as a concrete retaining wall (soil pressure, seismic and gravity loading) not design as deep beam. I used to create continous pile cap below the basement wall.
Also check the reaction of your pile, sometimes you must add your number of pile to resist the tension from uplift, seismic or the max combination of loading that you have..
Number and configuration of pile shall be resist the uplift and or tension force from overturning of your whole structure (upper and substructure as a unity)
regards,
robertsasmita
Here is my view...First we need to understand what is the behavior of the structure when all the loads are applied. We cannot just simply assumed that your wall can be designed as deep beam. We need to understand when a member is called a deep beam or a wall. If we follow ACI guidelines the assumption for deep flexural member or deep beam (good example is transfer beam and girder) is that it is loaded along the depth of the member meaning that it will have an in-plane bending but if the member will have to support an in-plane axial loading and out-of plane bending it is defined as wall thus making your case as a retaining wall with lateral and compressive load.
my two cents.
I would agree with both of u that the basement wall should be treated as wall rather a deep beam. However this wall has to span between support (in this case foundation piles) which still make it back to be like a beam set up (unless u put another beam below to transfer the wall load)and its a definately 'deep' since its a wall between floors.
After hearing from robertsas's #13, i decided i will make my foundation piles as close as possible to 'qualify' my wall support as a line support rather than point support.
I thank both of u for the precious views/comments. Thk i made 'mistakes' in my precious encounters. however, i received no complaint of the structures in distress, thanks to the safe (others may read that as conservative) design put up. I wil correct the assumption in my current project which also to be my deepest basement design so far in my career.
p/s: any1 of here is working comittee of ciria, maybe can suggest to them to take out the basement wall illustration from their deep beam design guide introduction...haha
It is not economical to put the piles on a closer distance to act like a continuous support for your wall. Number of piles is decided on the actual axial load transferred from your wall load. In any case your wall will still be supported continuously as you need to have a continuous pile cap so that all loads will be transferred correctly to your piles and eventually to your soil foundation. Even if you are just using micropiles it still need a reasonable width of pile cap that is most likely still be more than the width of your wall making it a continuously supported wall with continuous footing (pile cap) that transfers the load to your piles.