The problem of optimal sensor placement plays a key role in the success of structural health monitoring (SHM) systems. In this study, a new method is presented to investigate the optimization problem of sensor placement on gantry crane structures. The method is a combination of an improved harmony search (HS) algorithm and the modal assurance criterion (MAC). Firstly, we review previous studies on setting reasonable values for HS parameters that have the most impact on the result, and highlight the lack of general rules governing this aspect. Based on more efficient HS algorithms resulting from those studies, we apply our proposed technique to the optimization problem of sensor placement on gantry crane structures. The purpose of the optimization method is to select the optimal sensor locations on gantry crane girders to establish a sensor network for an SHM system. Our results show that the HS algorithm is a powerful search and optimization technique that can lead to a better solution to the problem of engineering optimization. The mode of a crane structure could be identified more easily when different mode shape orientations are considered comprehensively.
