A Numerical Study of Soil Confinement Effects on the Elastic Buckling of Large-Span Soil–Steel Bridges
Received: 9 March 2026 | Revised: 5 April 2026 | Accepted: 17 April 2026 | Online: 6 June 2026
Corresponding author: Amer Wadi
Abstract
The structural performance of soil–steel composite bridges is governed by the interaction between the corrugated steel shell and the surrounding soil, with elastic buckling being a key stability limit state. This effect occurs in all buried structures but becomes increasingly significant for large-span configurations under reduced soil confinement. This paper presents a numerical investigation of how soil cover influences elastic buckling behavior, using a consistent finite element eigenvalue analysis framework. A total of 45 cases, including several large-span structural profiles with varying corrugation stiffness and soil properties, were analyzed under both deep-burial and zero-cover conditions. Soil support was represented using a Winkler-type Spring model, with uniform stiffness for deep burial and depth-dependent stiffness for the zero-cover case to capture the loss of confinement near the crown. The results show that deeply buried structures follow a clear stiffness-controlled buckling trend, whereas shallow and zero-cover conditions lead to strong dependence on structural geometry and overall system flexibility. Based on these observations, an adjustment to existing elastic buckling formulations is proposed to better capture reduced confinement effects while remaining conservative relative to current design practice. The findings provide improved insights into elastic buckling behavior and support a more reliable and conservative stability assessment in practical design under shallow cover conditions, particularly for large-span soil–steel composite bridges.
Keywords:
flexible culvert, soil–steel composite bridge, buckling, stability, soil–structure interaction, numerical analysis, large-span bridgesReferences
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Copyright (c) 2026 Amer Wadi, Sokrates Ioannou, Yousef Alqaryouti, Ahmed Alqarawi
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