Deep beam as retaining wall
Current time: 10-27-2021, 06:15 PM
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Author: concreteok
Last Post: dynamics
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Deep beam as retaining wall
Currently i am working on a 3 level basement wall (cut and cover method). I am trying to use the last level wall as a deep beam to take vertical load and to span across foundation piles and serving as retaining wall spanning between floors. I would like to know anyone has done something similar. Any relevant reference to this? I am quite confident it can be done this way as this application is shown in CIRIA guide on deep beam but not guidance given.
concrete solution advocate
I have used that solution considering the lateral push generated by the Earth like a torsion load throughout the beam, and restricting the deflection on it, designing like a beam over an elastic support, where the piles are the absolute restrictions in the vane of the beam. The model has worked until the previous moment as in calculation...

can u elaborate more? do not quite get it. for my case the torsion is not substantial as the whole wall will be strutted by building floor.
concrete solution advocate
oanm2000, if you could describe your basement wall configuration with more details, forum members will have better idea on issue(s) and give you some ideas. Anyways, thanks for posting your concern and I am guessing other members will be interested on this.

The wall had a height of 2,80 meters, and had to cover a 14 metres length overall.
The model that I established was a beam of 3,15 meters high by 0,30 meters of thickness (the slab superior was 25 cm), with two intermediate supports on small caps for a single pile.
On the face of the beam that received the push of the embankment, I placed a lateral load equivalent to the load of the land, to a height of a third of the base of the beam. Like the model it was to solve it like a simple beam, like a simplified model, I replaced the lateral load by a equivalent torsion load.
When I calculating the beam of the indicated section, I had values of reinforcement similar to the obtained ones later, with the use of a software for retainin walls.
Until the moment neither cracks neither problems of deformation in that beam have been reported, almost six years later.
my case will be predominant taking a 12m deep earth lateral load and the same time 3 level carpark load. i need to design and detail it as deep beam and retaining structure. torsion should not be critical here as this beam top and bottom will be strutted against stiff floors structures. any opinion from others?
concrete solution advocate
The wall dimensions are considerable. The stresses due to the pressures behind the wall are difficult to simplify with a view to calculate the wall like a beam. I consider that the best thing is to calculate the wall like so, modeling it with support embedded in the points of the piles caps or with continuous support, following the final building model, I think
The case that you present is very interesting to discuss. I had already discussing with other colleagues
Thanks a lot
The book "Reinforced Concrete Deep Beams" by Prof FK Kong, that I downloaded from this forum is excelent. Is a good idea review it first to attack your problem.
I did a skimming of the text and I found two suggestions (about the model basically). I recommended this reading to you
Dear concreteok, why you design your basement wall with deep beam assumption? Is it for the wall on middle section of your basement or for the edge wall ? In deep beam theory, the beam only support with simple support or continous support as laboratory tested. They are no supported/restrained by soil and have no lateral load like soil pressure or seismic. If you have a big vertical load from column above, you can assumption a part of the wall below the load as column for example 1 meter width, still check dimension requirement. And calculate the number of pile below.

I normally assume the last wall between the last two floors as a deep beam (as ilustrated in ciria publication of deep beam, but unfortunately it did not address this type of design) spanning across piles. I have completed a few project with the same assumption but those are less critical ( and i was very conservative at those time). The current one, i have 3 floors basement, i.e., 4 floors loading going into the deep beams. Hope my explanation is clear here. if not, i can elaborate. thks for showing interest.
concrete solution advocate

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