Response reconstruction based on substructural condensation and modal-group superposition

Abstract

Abstract Increasingly complex civil structures result in an enormous consumption of computational resources in response reconstruction. Moreover, common closely spaced modes (CSMs) also impair reconstruction performance. This study proposed an improved approach that incorporated substructural condensation and modal-group superposition. This method efficiently extrapolated the desired response by dividing the entire finite element model into multiple manageable substructures, which were then condensed and assembled into a super-element model with fewer degrees of freedom (DOFs). The reconstruction response was directly performed on the condensed model by selectively retaining the physically measured DOFs during the condensation process. To address the challenges posed by CSMs, defined modal group responses (MGRs) were extracted from dynamic measurements using empirical mode decomposition. Based on these results, the corresponding MGRs at inaccessible locations were extrapolated using a condensed model. Finally, all the MGRs are superposed to form the desired response. Numerical and experimental tests were conducted to demonstrate the efficiency and accuracy of the proposed approach. The effects of substructural division, measurement noise, and measurement locations on the reconstruction were studied in detail.