Erciyes Üniversitesi Fen Bilimleri Enstitüsü Fen Bilimleri Dergisi 1012-2354 Erciyes Üniversitesi 10.65520/erciyesfen.1791972 Numerical Modelization in Civil Engineering Transportation Engineering İnşaat Mühendisliğinde Sayısal Modelleme Ulaştırma Mühendisliği Dönemeç İçine İnşa Edilen Çelik Otokorkulukların Konkav ve Konveks Durumlarının En 1317 Standardındaki Güvenlik Parametrelerine Etkisinin Sonlu Elemanlar Analizi ile Araştırılması Investigation of the Effects of Concave and Convex Conditions of Steel Guardrails Installed Inside Curves on the Safety Parameters According to the EN 1317 Standard Using Finite Element Analysis https://orcid.org/0000-0002-8504-7611 Ozcanan Sedat SIRNAK UNIVERSITY https://orcid.org/0000-0001-5039-2477 Özcan Özgür ŞIRNAK ÜNİVERSİTESİ https://orcid.org/0000-0002-6858-1521 Acar Zeynel ŞIRNAK ÜNİVERSİTESİ 03 26 2026 42 1 09 26 2025 02 09 2026 Copyright © 1985, Erciyes Üniversitesi Fen Bilimleri Enstitüsü Fen Bilimleri Dergisi 1985 Erciyes Üniversitesi Fen Bilimleri Enstitüsü Fen Bilimleri Dergisi

Çelik otokorkuluk sistemleri, özellikle kaza oranlarının yüksek olduğu yatay kurplarda meydana gelen yoldan çıkma kazalarında yaralanma şiddetinin azaltılmasında kritik bir rol oynamaktadır. Ancak EN 1317 standardında tanımlanan doğrulama prosedürleri ağırlıklı olarak düz yol kesitlerinde gerçekleştirilen çarpışma testlerine dayanmaktadır ve eğrisel yol geometrilerinin etkisi yeterince dikkate alınmamaktadır. Bu çalışmada, konkav ve konveks yatay kurpların çelik otokorkuluk sistemlerinin güvenlik performansı üzerindeki etkileri sonlu elemanlar analizi (SEA) kullanılarak sayısal olarak incelenmiştir. EN 1317 ile uyumlu H1W4-A çelik otokorkuluk sistemi, TB11 çarpışma testi koşulları altında LS-DYNA yazılımı kullanılarak modellenmiş ve doğrulanmıştır. Doğrulanan model, 30 m ile 210 m arasında değişen yarıçaplara sahip konkav ve konveks kurp konfigürasyonlarına uyarlanmış ve toplam 14 adet sayısal çarpışma simülasyonu gerçekleştirilmiştir. Çalışmada, Hızlanma Şiddet İndeksi (ASI) ve Teorik Baş Çarpma Hızı (THIV) gibi yolcu güvenliğine ilişkin parametreler ile çalışma genişliği (W) ve çıkış açısı (α) gibi yapısal performans ölçütleri sistematik olarak değerlendirilmiş ve düz yol referans koşulları ile karşılaştırılmıştır. Elde edilen sonuçlar, konkav otokorkuluk sistemlerinin düz yol koşullarına kıyasla daha düşük ASI ve THIV değerleri sergileyerek daha az darbe şiddeti oluşturduğunu göstermektedir. Buna karşılık, konveks otokorkuluk sistemlerinin özellikle küçük yarıçaplı kurplarda daha yüksek ve kritik güvenlik seviyelerine yol açtığı belirlenmiştir. Çoğu konfigürasyon EN 1317 sınır değerleri içinde kalmasına rağmen, R30 konkav durumunda izin verilen çıkış açısı ve çalışma genişliği limitlerinin aşıldığı tespit edilmiştir. Bu bulgular, otokorkuluk güvenlik değerlendirmelerinde yol geometrisinin etkisinin mutlaka dikkate alınması gerektiğini ortaya koymaktadır.

Steel guardrail systems play a critical role in reducing injury severity during run-off-road crashes, especially on horizontal curves where accident rates are high. However, validation procedures defined in the EN 1317 standard are predominantly based on crash tests performed on straight road sections, and the influence of curved geometries is not sufficiently considered. This study numerically examines the effects of concave and convex horizontal curves on the safety performance of steel guardrails using finite element analysis (FEA). An EN 1317-compliant H1W4-A steel guardrail system was developed and validated under TB11 crash test conditions using LS-DYNA. The validated model was subsequently applied to concave and convex curve configurations with radii between 30 m and 210 m, resulting in a total of 14 numerical crash simulations. Key occupant safety parameters, namely the Acceleration Severity Index (ASI) and Theoretical Head Impact Velocity (THIV), together with structural performance measures such as working width (W) and exit angle (α), were systematically evaluated and compared with straight-road reference conditions. The results indicate that concave guardrails generally exhibit reduced impact severity, reflected by lower ASI and THIV values, compared to straight-road cases. In contrast, convex guardrails lead to higher and more critical safety indices, particularly at smaller radii. Although most configurations remain within EN 1317 limits, the R30 concave case exceeds allowable exit angle and working width thresholds. These findings highlight the necessity of incorporating road curvature effects into guardrail safety assessments.

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