Dowells to connect a new concrete
Dowells to connect a new concrete
(OP)
I need to extend a culvert (6' each side), for that need to design a new culvert without bottom (frame) and join to the existing culvert approx. 28' long. I want to know the best way to connect the new concrete section to the existing concrete frame. The beam or slab and the walls of the frame are 8" thick. The new section will be 6' wide (each side of the existing culvert) and 28' long. Should I use dowels or some other method to connect the new concrete? How should I specify the join?






RE: Dowells to connect a new concrete
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RE: Dowells to connect a new concrete
On the other hand, Could you give me your opinion about placing the new portion of curlvert independently of the old. Is it necessary to join the old with the new frame (culvert without bottom and had no fill over the top)??
Why no make it work separetly? Are the settlements very important (I know it depend on the soil but I have no data for the soil)?. What do you think about the option of making work the culverts separetly and providing some sealants for the joints. Do you know what are the advantages of using dowells?
I am sorry If I am asking obvios things for some people, but for me this is new.
Thanks!!
RE: Dowells to connect a new concrete
1. When water flows through it, you want to minimize the chance that the water can get into the cracks between the the old & new concrete.
2. If a external load is applied to the culvert you don't want differential settlement.
Length of dowels is limited by the length of bits that are available to drill into the the existing concrete. Twelve inches is probably the MINIMUM embedment that I would consider... but that depends on the details.
You may want to go to my website (link below) and download the out-of-print document "Concrete Culverts & Conduits" on the Portland Cement Association page. Probably not a help on this problem, but a good reference if you work with these structures.
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RE: Dowells to connect a new concrete
The minimum dowel embedment depth and hole diameter are usually governed by the adhesive manufacturer's recommendations, and a consideration of how far away the dowels are from a free edge and how often spaced.
The actual embedment depth that is specified will also depend on the load that the dowel has to carry. Adhesive manufacturers such as Hilti and Powers/Rawl publish test data that indicate pullout and shear strengths for various types of dowels, base materials and substrate geometries. Suggest you get your hands on one of their catalogs.
The minimum projected length of the dowel can be determined using typical ACI data for rebar development length. Length will depend on whether you plan to resist shear or tension or both. In your case it sounds like no specific force can be calculated, you just need to tie the new and old sections well together.
Consider using a concrete bonding agent at the joint between new and old, as well as dowels. The b.a. is not expensive and can't hurt.
RE: Dowells to connect a new concrete
regards,
chichuck
RE: Dowells to connect a new concrete
If possible, I just want to know something else: Why in my case, no specific force can be calculated in order to determine the forces the dowells are going to take ?? Isn't it correct to determine the size and number of the dowells considering the shear produced at the edges of the span, at least for dawells along the leg of the frame (my frame is 9' long (span) by 6' wide, very small)?? Probably for that frame or culvert size, typical size of dawells are enough, however, I would like to know if my assumption to size the dowells is correct.
Thank you very much for all your help and time. GGC
RE: Dowells to connect a new concrete
RE: Dowells to connect a new concrete
Anyway good luck with your culvert .
RE: Dowells to connect a new concrete
These calculations will determine the maximum number of dowels that can be used... that is just the best that you can do under the circumstances. The nice thing is that it is usually "good enough".
www.SlideRuleEra.net
RE: Dowells to connect a new concrete
I read most of the referenced you recommended.
Thanks !!! GGC