Static‐Strain Level Change Together with Detection of Transient Signal as Damage Indicator for Truss and Frame Structures

Abstract

ABSTRACTThe lifetime prolongation of the old industrial structures is an important economic issue. Damage detection techniques can be helpful to warn about any structural deterioration and to assure sufficient time for counteraction activities. In the paper, the results of strain measurements on scaled leg model of offshore oil platform with different damage cases are presented. The considered damage cases were yielding, chord cutting and brace–chord detachment located in the bottom part of the model. Yielding was detected mainly by the sensors located in the lower part of the structure. On the other hand, brace–chord detachment was detected by all sensors on the structure. Therefore, the global character of the considered damage indicator is proven at least for some important class of damage cases. Due to transient response during brace–chord detachment and interpretation problems of results for partial chord cutting, the necessity of continuous monitoring was evident. The time point of detachment occurrence can be easily detected using difference or cross‐correlation technique. The change in static‐strain levels together with the detection of transient signal seems to be a simple and an effective damage indicator based on interrogation of thermo‐mechanical strains.