Faculty of Mechanical and Manufacturing Engineering
Book 2.1 - Mechanical Engineering and Mechanics
FRI-1.317-1-MEMBT-09
COMPARATIVE ANALYSIS OF VARIOUS W-BEAM GUARDRAIL DESIGNS
Abstract: The structural integrity and crashworthiness of roadside W-beam guardrail systems are
essential for occupant safety during collision scenarios. Standard W-beam constructions often need vertical steel posts positioned at 2.0 metres to satisfy Test Level 3 (MASH) performance standards. Nonetheless, practical limitations, such as shallow subterranean utilities, sometimes inhibit the installation of a post, requiring alternative solutions. This
research examines the effectiveness of a modified W-beam system with double-layered rails, bolted in tandem, that extend 4.0 metres between two posts. A comprehensive finite element model was created in LS-DYNA to simulate vehicle collision dynamics and evaluate barrier deflection, energy absorption, and structural performance. Concurrent analytical computations were conducted in MATLAB employing EN 1317-1 to assess the Theoretical Head Impact Velocity (THIV) and Acceleration Severity Index (ASI). The LS-DYNA findings indicated that the redesigned barrier sustained deflection levels within permissible TL-3 limits during impact situations. The analytical results aligned well with the simulation data, validating the proposed architecture. The results validate that a twin W-beam layout may offset the absence of a post and maintain safety performance. This study offers engineers a verified, simulation-driven
option for barrier design in restricted highway settings.
essential for occupant safety during collision scenarios. Standard W-beam constructions often need vertical steel posts positioned at 2.0 metres to satisfy Test Level 3 (MASH) performance standards. Nonetheless, practical limitations, such as shallow subterranean utilities, sometimes inhibit the installation of a post, requiring alternative solutions. This
research examines the effectiveness of a modified W-beam system with double-layered rails, bolted in tandem, that extend 4.0 metres between two posts. A comprehensive finite element model was created in LS-DYNA to simulate vehicle collision dynamics and evaluate barrier deflection, energy absorption, and structural performance. Concurrent analytical computations were conducted in MATLAB employing EN 1317-1 to assess the Theoretical Head Impact Velocity (THIV) and Acceleration Severity Index (ASI). The LS-DYNA findings indicated that the redesigned barrier sustained deflection levels within permissible TL-3 limits during impact situations. The analytical results aligned well with the simulation data, validating the proposed architecture. The results validate that a twin W-beam layout may offset the absence of a post and maintain safety performance. This study offers engineers a verified, simulation-driven
option for barrier design in restricted highway settings.
Keywords: W-beam, Model, LS-DYNA, FEM, THIV, ASI, simulation, crashworthiness, modified guard, rail.
REFERENCES
- Teng, T., Liang, C., & Tran, T. (2015). Effect of various W-beam guardrail post spacings and rail heights on safety performance. Advances in Mechanical Engineering, 7. https://doi.org/10.1177/1687814015615544.
- EN 1317-1: 2010. Road restraint systems. Part 1: Therminology and general criteria for test methods.
- EN 1317-2: 2010. Road restraint systems. Part 2: Performance classes, impact test acceptance criteria and test methods for safety barriers including vehicle parapets.
- LS-DYNA support files. https://www.dynasupport.com/tutorial/ls-dyna-users-guide/time-integration
- Иванов, И., (2023). Строителна динамика и сеизмичен анализ. Лекционни записки. Русенски Университет „Ангел Кънчев“.
- Lee, R., (2019). LS-Dyna for Engineers A Practical Tutorial Book. BW Publications ISN 9781703208856
- Lewis, B., (2004). FHWA-HRT-04-095 MANUAL FOR LS-DYNA SOIL MATERIAL MODEL 147. Federal Highway Administration Research and Development Turner-Fairbank Highway Research Center 6300 Georgetown Pike McLean, VA 22101-2296.