Vibration methods are used to approach changes in natural frequencies of the intact/damaged (concrete) structures and damage detection is only possible if the damage is significant. Stress-strain characteristics seem to be more reliable approach. Is it possible to relate strain measurements with the damage detection?
In very general terms, damage detection can be evaluated from the variation of the stress-strain slope (e.g. measured in compression until breaking), actually taking into account the shape of the beam and so on. A more sensitive technique is based on acoustic emission detection. Statistical analysis of acoustic emissions allows to identify as well the damage and the whole fracture mechanic behaviour.
In attach you can find a paper, as an example, anyway in my profile (and co-authors) you can find more papers on this topic. I do hope you helps.
Thanks a bunch. Regarding AE techniques as far as I remember yes it does detect as well as locate damage. But eventually I'd apply my technique in field testing. AE techniques have noise issues and environmental influences (please correct me if i am wrong).
The paper you attached. Thanks a bunch sir. I'd pursue the research related with it. I really appreciate it. Thanks.
Dear Usman,
actually AE technique is influenced by noise, as you said, nevertheless it is possible to filter out any background noise, with the due cautions. Besides, AE technique, not only allows to locate damage, but also indicate when crack start to grow and its evolution.
For further and more detailed information you can go through the profile of my collegue Giuseppe Lacidogna (present in Researchgate). There you can find a lot of papers about AE monitoring (in relation to elastic moduli and damage detection).
If it indicates crack growth then it can be employed in real time health monitoring. As my research will focus on bridges, I will focus on AE techniques in that perspective. Thanks a bunch. I have started going into research of Mr. Lacidogna. I really appreciate your help. If you don't mind I'd come back to you after I have enough knowledge of Acoustic emissions or get any idea.
Thank you.
Dear Usman,
in order to detect damage on RC structures we are using the modal curvature variation (evaluated before, during and after an earthquake). The absolute value of the curvature variation is strictly related to the maximum interstory drift. Then, using this kind of approach, it is possible to quantify and localize the damge occurred on a framed structure. It is my pleasure, to send you some of my recent papers about this topic. For any question, do not esitate to contact me.
Sincerely,
Rocco
Article Automatic evaluation of the fundamental frequency variations...
Article Localization of Damage Occurred on Framed Structures: Analys...
Article Analysis of non-stationary structural systems by using a ban...
In the attached paper, a strain DLV method is proposed by combining DLV method with static strain measurement.
The strain DLV approach determines the set of load vectors that span the nullspace
of the change in strain flexibility. These load vectors result in the same strain fields before and after damage. To obtain the same strain field even though the structure has damage, the strain DLVs do not induce strain at the damaged members. Using
this concept, the elements, which have no internal force, when they are subjected to the strain DLV, are candidate damage elements
http://sstl.cee.illinois.edu/papers/smss07_shinae.pdf
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