A laser-based quality control of screw penetration in mass timber connections

Abstract

Mass timber is a relatively new and sustainable construction material that can carry large loads. Such loads require new connections that often use very long screws. However, ensuring their mechanical integrity against overtightening is paramount for structural safety. Traditional manual evaluations present limitations. This research employs laser scanning technology for automated evaluation of screw penetration in wood-aluminum interfaces using VGS9180 screws. By applying torque ranging from 10 to 50 Nm in 5 Nm intervals, a critical torque-penetration correlation emerged, highlighting a sensitive range between 35-40 Nm. Within this range, small overtightening can jeopardize the integrity of the connection. The study underscores laser scanning's efficacy in pinpointing improperly torqued screws, offering a potential leap in quality assurance for timber construction. The results of this study indicate a threshold-based method can detect overtightened screws on the experimental setup when the distance between two surfaces falls beyond 3.2 mm.