Selection of Optimal Sensor Locations Based on Modified Effective Independence Method: Case Study on a Gothic Revival Cathedral

Abstract

This study demonstrates a methodology for selecting optimal regions for placing vibration sensors to efficiently extract the dynamic characteristics of the nave of the Cathedral of St. John the Divine (SJD). Placing sensors at optimal regions reduces not only the cost and time demands of vibration testing but also the amount of measurement data that needs to be postprocessed. Optimal sensor locations are determined by exploiting the finite-element (FE) model of the cathedral nave, built according to available documentation and best-engineering judgment and correlated against on-site measurement and inspection data. Optimal sensor locations are determined through a modified version of the effective independence method (MEIM) using the mode shape predictions of the correlated FE model. In (MEIM), there are two conflicting objectives: maximizing the orthogonality of mode-shape vectors of interest through an information-gain-based criterion while effectively exploring the geometry of the structure and avoiding spatial aliasing through a distance-based criterion. The study investigates the tradeoff between these two objectives and determines the regions of the cathedral nave that are consistently identified as optimal for sensor placement. To ensure the validity of the findings presented, the robustness of the (MEIM) to potential inaccuracies in the FE model is also demonstrated. In the absence of prior information regarding the modal behavior of a Gothic-style cathedral, the regions identified therein can be considered plausible locations for sensor placement in future studies.