Impact Angle-Based Section Design and Optimization of the C Post in Order to Improve the Safety and Structural Performance of Guardrails

Öz

This study focuses on enhancing the performance of the C post in H1 containment-level guardrail systems by optimizing its design to better withstand angular impacts, common in roadside safety applications. Since the post plays a crucial role in transferring impact loads to the ground, modifications were made by adjusting the angle of the post edge that aligns with the impact direction, while keeping the perpendicular side constant. Two key test angles from EN1317 standards were used: a 20-degree angle (TB11) to assess safety metrics like the Acceleration Severity Index (ASI) and theoretical Head Impact Velocity (THIV), and a 15-degree angle (TB42) to evaluate structural performance, including working width and exit angle. Finite element modelling in LS-DYNA, followed by model validation and calibration, showed that aligning the C post angle more closely with crash angles improved both safety and structural integrity, resulting in a transition of the C post design toward a Z post shape with enhanced rigidity and performance.

Anahtar Kelimeler

• Guardrail systems
• post performance
• EN1317
• finite element analysis
• LS-DYNA

Kaynakça

1. T.-L. Teng, C. Liang, C. Hsu, C. Shih, and T. Tran, “Impact Performance of W-beam Guardrail Supported by Different Shaped Posts,” International Journal of Mechanical Engineering and Applications, vol. 4, no. 2, p. 59, 2016, doi: 10.11648/j.ijmea.20160402.14.
2. EN1317-2, Road restraint systems - Part 2: Performance classes, impact test acceptance criteria and test methods for safety barriers including vehicle parapets Dispositifs. 2010.
3. American Association of State Highway and Transportation Officials, Manual for assessing safety hardware, 2009. 2009, p. 259.
4. W. Wu and R. Thomson, “A study of the interaction between a guardrail post and soil during quasi-static and dynamic loading,” Int J Impact Eng, vol. 34, no. 5, pp. 883–898, 2007, doi: 10.1016/j.ijimpeng.2006.04.004.
5. O. Prentkovskis, A. Beljatynskij, E. Juodvalkiene, and R. Prentkovskiene, “A study of the deflections of metal road guardrail post,” Baltic Journal of Road and Bridge Engineering, vol. 5, no. 2, pp. 104–109, 2010, doi: 10.3846/bjrbe.2010.15.
6. N. M. Sheikh and R. P. Bligh, “Finite Element Modeling and Validation of Guardrail Steel Post Deflecting in Soil at Varying Embedment Depths,” 11th International LS-DYNA® Users Conference, no. 4, 2011.
7. S. Ozcanan and A. O. Atahan, “Radial basis function surrogate model-based optimization of guardrail post embedment depth in different soil conditions,” Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, vol. 234, no. 2–3, pp. 739–761, Feb. 2020, doi: 10.1177/0954407019848548.
8. M. Örnek, A. O. Atahan, Y. Türedi, M. M. Erdem, and M. Büyük, “Soil based design of highway guardrail post depths using pendulum impact tests,” Acta Geotechnica Slovenica, vol. 16, no. 2, pp. 77–89, 2019, doi: 10.18690/actageotechslov.16.2.77-89.2019.

9. A. O. Atahan, M. Büyük, M. Örnek, M. Erdem, and Y. Turedi, “Determination of optimum post embedment depth for C120 steel posts using field and full scale crash test,” International Journal of Crashworthiness, vol. 24, no. 5, pp. 533–542, 2019, doi: 10.1080/13588265.2018.1479499.
10. Ozcanan S. Head-on and angular impact-based investigation of mechanical behavior of guardrail post types with finite element analysis. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 2024;238(4):1112-1124. doi:10.1177/09544062231179990
11. D. Marzougui, P. Mohan, and S. Kan, “Evaluation of Rail Heights Effects on the Safety Performance of W - Beam Barriers,” FHWA/NHTSA National Crash Analysis Center, no. November, pp. 1–30, 2007.
12. K. S. Tan, W. Tan, and S. v. Wong, “Design of motorcyclist-friendly guardrail using finite element analysis,” International Journal of Crashworthiness, vol. 13, no. 5, pp. 567–577, 2008, doi: 10.1080/13588260802293186.
13. M. R. Ferdous, A. Abu-Odeh, R. P. Bligh, H. L. Jones, and N. M. Sheikh, “Performance limit analysis for common roadside and median barriers using LS-DYNA,” International Journal of Crashworthiness, vol. 16, no. 6, pp. 691–706, 2011, doi: 10.1080/13588265.2011.623023.
14. Z. Li, H. Fang, J. Fatoki, M. Gutowski, and Q. Wang, “A numerical study of strong-post double-faced W-beam and Thrie-beam guardrails under impacts of vehicles of multiple size classes,” Accid Anal Prev, vol. 159, no. June, p. 106286, 2021, doi: 10.1016/j.aap.2021.106286.
15. H. A. Whitworth, R. Bendidi, D. Marzougui, and R. Reiss, “Finite element modeling of the crash performance of roadside barriers,” International Journal of Crashworthiness, vol. 9, no. 1, pp. 35–43, 2004, doi: 10.1533/ijcr.2004.0270.
16. C. E. Hampton and H. C. Gabler, “Crash performance of strong-post W-beam guardrail with missing blockouts,” International Journal of Crashworthiness, vol. 17, no. 1, pp. 93–103, 2012, doi: 10.1080/13588265.2011.626931.
17. M. Klasztorny, D. Nycz, and R. Romanowski, “Rubber / Foam / Composite Overlay Onto Guide B of Barrier Located on Road Bend,” Archiwum Motoryzacji, vol. 69, no. November, pp. 65–86, 2015.
18. S. Ozcanan and A. O. Atahan, “RBF surrogate model and EN1317 collision safety-based optimization of two guardrails,” Structural and Multidisciplinary Optimization, vol. 60, no. 1, pp. 343–362, Jul. 2019, doi: 10.1007/s00158-019-02203-z.
19. S. Ozcanan and A. O. Atahan, “Minimization of Accident Severity Index in concrete barrier designs using an ensemble of radial basis function metamodel-based optimization,” Optimization and Engineering, vol. 22, no. 1, pp. 485–519, Mar. 2021, doi: 10.1007/s11081-020-09522-x.
20. İ. Yılmaz, İ. Yelek, S. Özcanan, A. O. Atahan, and J. M. Hiekmann, “Artificial neural network metamodeling-based design optimization of a continuous motorcyclists protection barrier system,” Structural and Multidisciplinary Optimization, 2021, doi: 10.1007/s00158-021-03080-1.
21. M. Y. Apak et al., “Finite element simulation and failure analysis of fixed bollard system according to the PAS 68:2013 standard,” Eng Fail Anal, vol. 135, no. February, p. 106151, 2022, doi: 10.1016/j.engfailanal.2022.106151.
22. H. I. Yumrutas, S. Ozcanan, and M. Y. Apak, “Experimental and numerical comparative crashworthiness analysis of innovative renewable hybrid barrier with conventional roadside barriers,” International Journal of Crashworthiness, vol. 0, no. 0, pp. 1–17, 2022, doi: 10.1080/13588265.2022.2075124.
23. Yorur, H., Ozcanan, S., Yumrutas, H. I., and Birinci, E. "Renewable hybrid roadside barrier: Optimization of timber thickness," BioResources 18(1), 2023, 804-82. DOI: 10.15376/biores.18.1.804-826
24. S. Ozcanan and O. Ozcan, “Criteria inadequacy of the vehicles used for the calculation of safety parameters in the EN1317-TB11 test,” 2022, doi: 10.1177/09544070221115010.
25. Ozcanan, S. (2023). Finite Element Analysis and Investigation of Critical Impact Point of Steel Guardrails Affecting Safety and Structural Performance. Turkish Journal of Civil Engineering, 34(2), 125-144. https://doi.org/10.18400/tjce.1238657
26. NCAC (2008) Finite element model archive, George Washington University FHWA/NHTSA National Crash Analysis Center, http:// www.ncac.gwu.edu/vml/models.html, Virginia (Accessed 2008)
27. Europan Norm, “BS EN 16303:2020 BSI Standards Publication Road restraint systems - Validation and verification process for the use of virtual testing in crash testing against vehicle restraint system,” 2020.
28. CSI (2017) Crash testing of H1 and H2 guardrails systems. 0021\ME\HRB\17, Bollate, Italy