The layout of structural bolts used in infrastructures are determined based on the mechanical and design requirements.Minimum spacing is set to facilitate construction and control stress concentration, and maximum spacing is set toprevent the intrusion of water between plates and provide sufficiently equal force distribution to each bolt. Ultrasonictesting is one of the most widely used and rapid in-situ inspection methods to evaluate the status of bolted connections;however, scattering from hole boundaries may mask reflections from the cracked and corroded surfaces. In currentpractice, the ultrasonic-based inspectability of bolted connections for the presence of crack and corrosion as well aspretension loss is not a design criterion. In this paper, the inspectability is added as a design variable within theboundaries of design limits that control spacing as well as distribution of bolts at the connection. The ideal spatialdistribution of different bolt groups is proposed to detect the critical crack length and area loss hidden between plates.The proposed bolt distribution is numerically tested to show the minimized influence of hole scatters to the ultrasonicinspectability of defects. The regression model is built to predict crack position and size.
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