huangyhg

precast pile cap
in order to achieve shortest down time, project engineers are requesting to explore the possibility of installing precast pile cap on a group of piles. pile cap size will be quite large - over all size may be 3m x 14m.
i designed pile caps before but never used a precast pile cap. a theoretical solution may be possible, but installation of the concept in real life could be a real challenge.
any suggestion / advise on this matter will be of immense help to me.

possible but not much potential savings in cost, some savings in time is possible. the amount cost for formwork, concrete and rebar installation is similar whether or not done in the factory of in the field. prestressing can be easily done in the field.
ask the project engineers for their ideas/design and assess if it will work.
the difficulty is not on the cap design, is at the pile-cap interface. connection details (such as special reinforcing/embedments/grouting) and feasibility/ease of construction are the keys. if there is no one in the company has done it before, suggest to talk to a few experienced contractors during the project development stage.
i have a drawing that i can post when i get back to the office in a day or so. it's a precast cap beam for a pile bent. it's been a while but i'd say it's about 5' wide x 4' deep x about 70' long - it two pieces. it sits on 5' diameter drilled shafts.
it's for a bridge over a waterway; it you think it'll be useful let me know.
anyway, if your cap is 3 x 14 x d, it's not exactly the easiest thing to ship and lift. on my bridge job, everything is shipped by barge from fabricator to erector.
thank you all for your suggestions. i am not very keen to do this before getting a complete brief. my biggest concern is the connection, as kslee1000 has commented.
bridgebuster, any reference drawing will be very important for my design development and discussion. please forward me the copy of the drawing you mentioned. yes, the size is a problem for lifting. if this concept really goes ahead, i will be inclined to split the raft in 3 sections and design the connection(s)separately. just a thought.
here they are; the file contains three drawings.
good luck.
bridgebuster - thanks a lot for the information. i will study them now.
you're welcome.

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