Structure inspection manuals such as the Ontario Structure Inspection Manual (OSIM) mostly emphasizes on the visual inspection and physical condition of bridge structures. The visual inspection methodology in this guideline consists of close up visual assessment of defects in the superstructure and substructure. This methodology is limited to inspection of elements that are at the arms length. For elements with difficult access (i.e. long girders mid-span or deck over river or highways), the methodology is not very practical or accurate. Also, the methodology does not provide any information on how to evaluate concrete piles or foundations.
Stein and Sedmera (2006) reported that approximately 60,000 bridges throughout the US has been identified as having unknown foundations. As the author’s knowledge, this condition might be same in Canada. This is crucial because Canada owns a huge number of bridge and civil infrastructure facilities built between 1950 and 1980. These bridges and infrastructure are widely distributed across Canada, owned by counties, towns, municipalities, and provincial and federal governments. Most of these bridges and infrastructure need to be upgraded in accordance with the new code and standard requirements. To do so, it is essential to have enough information about the present condition of (unknown) foundations and piles.
How to Evaluate Concrete Piles?
A reliable condition assessment of substructures (foundations and piles) needs a basic information about type, material and as-built dimension. When foundations and piles are accessible, visual inspection, and mechanical loading of the piles is an effective option. This involves identifying the location of piles (or group of piles), and in-place static or dynamic loading tests to evaluate the reliability of piles and foundations. However, when the access to the piles is not possible, other techniques should be used. NDT methods provide a very reliable and practical alternative for testing and evaluating this group of piles.
Non Destructive Evaluation of Piles and Foundations
Different NDT methods exist for surveying foundations and piles. To select the best methodology for condition assessment of substructure, following factors should be considered:
1. Type and material of foundation (e.g. timber, reinforced concrete pile, steel pile, composite system)
2. Structural system of substructure (e.g. pile, foundation, or a combined system of foundation and pile)
3. Pile condition (exposed or covered up by pile cap)
4. Pile surrounding area
6. Pile configuration in the layout
5. Ground water level
6. Foundation geometry
The NDT methods for unknown foundation and pile survey are in two main groups as of:
A. Surface Methods; and
B. Sub-Surface Methods.
Surface Methods
Surface methods include NDT methods in which both acoustic wave source and receiver are placed at the surface. A probe signal propagates into unknown foundations, reflected off the foundation ends and boundaries. The received signal at the surface is used for post analyses.
Sub-Surface Methods
The subsurface methods mostly include a probe borehole near to unknown foundation. A borehole or a group of borehole are drilled within surrounding areas. In these methods, the probe signal emitted into unknown foundation, receiving by an adapted transducer placed within borehole.
Other NDT methods
Acoustic surface methods can obtain simultaneously the following information:
1. Pile dimension (pile length)
2. Pile stiffness variations: this parameter can be correlated to cross section variation of pile in cast in-place concrete piles
3. Crack and defect location
Hasan S Akhtar
I was expecting the article to be a bit more informative.
FPrimeC
Dear Hasan. Sorry if the article has not met your expectations.
These are not technical notes, but only brief introductory notes to the topic of NDT in concrete testing.
We appreciate if you want to contribute to our newsletter and blog.
All the best
Dipak Bhattacharya
dear FPrimeC,
Why not invite the Pile Contractors who can enrich the professional contributions as well as let the future clients know their expertise in the specific fields?
Every body cannot contribute professional expertise in every field, but may like to enrich their own knowledge on subjects they do not know much.
Thanks,
Dipak Bhattacharya.
FCO RAMIREZ
WHO SELL THIS EQUIPEMENT
Carlos Fernández
Francisco: nosotros podemos ayudarte a conseguir equipos para ensayos de integridad de pilotes.
Saludos,
Carlos Fernandez Tadeo
Stan Smith
We manufacturer NDE testing equipment that is useful in these foundation investigations. Olson Instruments has both surface and subsurface equipment. Please feel free to contact me if you would like additional information.
Best regards,
Stan Smith
Carlos Rodriguez
muy interesante el escrito
saludos
FPrimeC
Gracias Carlos
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Violette Lebrac
It's scary to think that 60,000 bridges in America have unknown foundations. I'd imagine that a bridge collapse would be really expensive and destructive. If I were having a bridge built, I'd want to make sure the pile design is evaluated by a professional service.
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Hannah Neilson
I never knew that you would want to consider things like the material that a piling is made out of. It would be smart to choose something that is durable and going to last a long time as well. I'm working on pouring the foundation for my home and need a piling contractor to help. When I find them, I'll have to consider the materials they use.
Sam Li
I like what you said about non-destructive evaluation of piles in order to check contents. I would say that piling services are essential when building a home. My friend is in need of such services, so I'll help him find the best business out there.
Kristofer Van Wagner
You make an interesting point that a reliable contractor knows the right material to use. My mother is building a new guest house and she needs to hire a piling contractor. I will remind her to hire a certified contractor.