Performance of steel dynamic message sign-support structures in extreme wind events

Abstract

With a focus on addressing the fatigue-related issues, overhead truss dynamic message sign (DMS)-support structures have witnessed a material shift from aluminum to steel, further to a shift in their connection details from welded tube to slotted tube gusset plate connections. While the effect of fatigue on this category of structures has been investigated through field monitoring programs and numerical simulations, the potential vulnerability of DMS-support structures to extreme winds has remained largely unexplored. To address this research gap, the current study aims to evaluate the structural response and assess the possibility of failure of overhead truss DMS-support structures under a wide range of wind loading scenarios. For this purpose, a representative finite-element (FE) model is developed with all the necessary details. The FE model is first validated using the data from the field-instrumented DMS-support structures. The validated FE model is then subjected to extreme wind loads of various intensities. The main structural response measures are studied, including those for the U-bolt connections that tie the horizontal truss to the vertical supports. To obtain the most realistic results, the wind simulations examine the code-specified drag coefficients in comparison to the drag coefficients refined through an advanced computational fluid dynamics study. The performance of the steel DMS-support structures is further examined considering various contributing factors, with a special attention to the loading demand experienced by connections, columns, and chords. This provides a holistic vulnerability assessment of this important category of structural systems subjected to extreme wind events.