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  • 1.  Fencing foundation design - ideas

    Posted 10-16-2017 03:29 PM
    Hello all,

    I am trying to get critical design inputs for security fence foundation design.

    I see that the current design is a cuboid 35x35x 65 cm height. 

    I am looking at a conical shape with 25 cm Dia at the top and 35,cm at the bottom with the same height. (similar to a inverted a bucket) 

    There is a 40% saving in concrete. The shuttering is simpler. Installing is easier. 

    I wonder if there is any design impact. 

    Looking for inputs from fellow engineers. 

    Kalyan Emandi C.Eng, M.ASCE
    Sr Project Engineer

  • 2.  RE: Fencing foundation design - ideas

    Posted 10-17-2017 02:21 PM
    Hi, have you considered short piling instead? Manual labor is reduced to the minimum, no shuttering, no backfiling, good moment-resisting capacity and improved resistance to flood-induced scour. Productivity can easily increase ten-fold.

    Joram Amir P.E., D.GE, F.ASCE
    Herzlia, Israel

  • 3.  RE: Fencing foundation design - ideas

    Posted 10-17-2017 02:21 PM
    Construction is not simpler, when you have dig a hole that is wider at the bottom then on the top.

    Robert Scancella P.E., M.ASCE
    Chief Engineer CEI
    Bayville NJ

  • 4.  RE: Fencing foundation design - ideas

    Posted 10-17-2017 04:26 PM
    Your design seems to require backfilling over the foundation.  I'm wondering if the backfill material will have the same resistance capacity as undisturbed earth such as would be achieved in short piling.  The backfill compaction requirement will cause you to lose much of your concrete saving vs. short piling which requires no backfill.

    James Anderson P.E., M.ASCE
    Project Engineer
    North Richland Hills TX

  • 5.  RE: Fencing foundation design - ideas

    Posted 10-17-2017 03:45 PM
    ​Hi Kalayan:
    You have not mentioned what kind of soil you have over there as you will need to accommodate any proposed solution to the soil condition.
    One suggested method would be to have he foundations pre-cast (either cuboid or conical or cylindrical and checked for bearing capacity, overturning moments etc), dig the hole in the ground, drop the foundations, plumb and aligned etc. backfill holes with selected backfill, compact and then insert the posts in the holes of the foundation, and grout the posts in the foundation hole after the posts are plumbed and heights checked.

    Abdul Muqtadir P.E., M.ASCE
    Monroe Township NJ

  • 6.  RE: Fencing foundation design - ideas

    Posted 10-18-2017 02:25 PM

    I am pleasantly surprised at the number of options and ideas suggested. I need to thank you before I go any further on this .

    I've recently moved to Senegal (West Africa). The purpose of sharing is to invite ideas from different perspective. while I do believe that there are better options available, I do have constraints.

    Hence, I need to find the best possible solution to deliver with available resources within the shortest possible time. 

    . Information /materials at hand:
    1. Terrain : Silty Sand CBR Value 20
    2. Backfill material : Laterite (locally available) 
    3. Fencing post : 2inch GI Pipe (Locally available) (1.8m  in total , 1.5 above ground  and 30 cm embedded )
    4. Fencing Mesh : Diamond mesh (locally Available)
    5. Fence foundation : under discussion
    6. Equipment Available : JCB ( Backhoe)

    Joram Amir & James Anderson :

    Thank you for the suggestion. I would definitely consider it. I do have a constraint, the equipment is not available in the local market. its only 60 cm deep, can I buy an Auger instead ?

    Terrain is characteristics :
    1) Clay (1st location)
    2) sand (2nd Location)

    I do need backfill, Laterite is an amazing material available locally which can be used for backfill. When I calculated the budget , backfill is turning out to be a cheaper option than concrete.

    Robert Scancella:

    Dear Robert, 
    Yes, the bottom is wider than the top. Standard fencing is 60 cm long (30 X 30) cm wide column. I have reduced the top width and changed it into conical shape. ( No edges ! )

    Top of concrete  diameter is  20 cm, bottom diameter is 35 cm. The bucket width of the backhoe is 40 cm. There is no effect on the excavation.

    Abdul Muqtadir

    Dear Abdul,

    Absolutely! agree with you. That's the concept I am proceeding with! . will update the progress as it takes shape. 

    Thanks for the suggestions!!! Its a pleasure, will be back with more discussions.

    Kalyan Emandi
    Sr.Project Engineer