Dr. Lauren K. Stewart

Project Information

PI: David Scott, Co-PI: Lauren Stewart and Don White

Student: Esmaeel Bakhtiary and Joseph Lee

Dates: January 1, 2016 - Nov 22, 2017

Funding: $724,000 (Phase II and III)

Summary

Asphalt pavement mow strips, used as a vegetation barrier in guardrail systems, have typically been regarded as a rigid layer in roadside design. However, geometric parameters of the mow strip such as thickness and rear distance behind the post have a significant impact on the amount of restraint the asphalt layer provides to resist translation and rotation by the posts. In this research, a standard steel guardrail post designed with a range of asphalt mow strip dimensions is evaluated via computational and experimental methods. A survey of the use of asphalt pavement mow strips in the United States was undertaken to determine an initial set of mow strip designs for investigation. Static and dynamic tests were performed based on these designs, and finite element models were calibrated using the test data and parallel material characterization experiments. Utilizing the calibrated finite element model, simulations were performed on a wide variety of asphalt mow strip designs. Simulation and experimental results were correlated to develop a set of quantitative performance criteria. These criteria were used to assess the amount of ground-level restraint on a guardrail post caused by a given asphalt mow strip design in comparison with the existing design recommended by American Association of State Highway and Transportation Officials.

Publications

Lee, S., Bakhtiary, E., Scott, D., Stewart, L.K., White, D. (2017). Influence of geometric parameters on the restraint of guardrail posts by asphalt mow strips. Sustainable and Resilient Infrastructure, 2(1), 22-36. Link to pdf

Bakhtiary, E., Lee, S., Scott, D., Stewart, L.K., White D. (2017). Evaluation of Guardrail Posts Installed in Asphalt Mow Strips by Static Finite Element Simulation. Open Journal of Civil Engineering, 7, 141-164. Link to pdf

Lee, S., Bakhtiary, E., Stewart, L.K., Scott, D., White, D. (2016). Effect of pre-cut asphalt fracture planes on highway guardrail performance. In G. Schleyer & C.A. Brebbia. Structures Under Shock and Impact XIV. Paper presented at SUSI 2016, Crete, Greece. Wessex, UK: WIT Press. (Selected for Special Issue: International Journal of Computational Methods and Experimental Measurements, 4(3), 353-363.) Link to pdf

Lee, S. (2017). Static and dynamic assessment of the influence of asphalt layers on the structural response of steel guardrail posts. Link to dissertation

Bakhtiary, E. (2017). Assessment of guardrail systems with a stiff surficial layer via continuum and discrete simulations. Link to dissertation