On stick–slip phenomenon as primary mechanism behind structural damping in wind-resistant design applications

Structural damping, particularly in wind-resistant design applications where the main structure is desired to generally remain within linear-elastic limits, has been widely attributed to a stick–slip mechanism occurring at material interfaces between primary structural members and secondary components. However, no one has yet proven this analytically using an appropriate mathematical model and probabilistic considerations. A theoretical expression for damping due to one stick–slip component (SSC) in a simple linear 1DOF system is thus first derived. In actual structures, there can be a very large number of SSCs, so theoretical expressions are then derived to pursue the study for a number of different cases, also considering different probability distributions to characterize the large number of unknown parameters. One apparent result from all analyses carried out is found: damping increases but eventually decreases with amplitude due to these SSCs. This amplitude dependency of structural damping can be observed in measurements on actual structures, demonstrating that the stick–slip phenomenon can indeed be a primary mechanism behind structural damping in wind-resistant design applications. Finally, the implication on the design wind loads of using the derived model in contrast to current models is discussed, illustrating a limitation in these damping models.