EXPERIMENTAL. MODAL. ANALYSIS OF REINFORCED CONCRETE STRUCTURES

Experimental modal analysis techniques have been shown to be applicable to both laboratory test specimens and in situ test structures made of reinforced concrete. These techniques, in general, apply only to linear structures; however, many concrete structures are designed to remain in the linear, uncracked response region during dynamic excitation (nuclear power plant structures, for example). Data from the experimental analyses agreed well with finite-element modal analysis results, and the numerical models were further refined based on the experimental results. Because of the relatively low excitation levels required, these methods provide engineers with techniques for assessing the as-built condition of a structure without introducing damage into the structure. If a concrete structure is damaged, the experimental modal analysis methods could possibly be used to monitor its deterioration.
Further investigations are needed to evaluate the sensitivity to damage of the experimentally determined modal properties. Also, methods must be found to determine, without prior modal data, if an in-situ structure is in a damaged state. These topics are being pursued by other researchers in the experimental modal analysis field.⁶
In its current form, experimental modal analysis methods can provide both practicing and research engineers with a valuable tool for verifying dynamic properties of reinforced concrete structures.