- Journal Article
The paper revisits the notorious collapse of 18 spans of the elevated Route No. 3 of Hanshin Expressway during the 1995 Kobe earthquake. The overturned deck was monolithically connected to 3.1 m diameter piers, which failed dramatically. In stark contrast, the massive 17–pile groups survived the earthquake and are still in use, supporting the new bridge. The scope of the study is dual. Initially, the actual pile group–bridge–soil system is investigated employing the finite element (FE) method, accounting for material and geometric nonlinearities. Reinforced concrete (RC) members (pier and piles) are modelled using the Concrete Damaged Plasticity (CDP) model, while a kinematic hardening model is employed for the soil. The numerical simulation reproduces the observed shear-dominated failure at the region of reinforcement cut-off. The analysis reveals that the pile group sustains non-negligible rocking during shaking (despite being over-designed), leading to alternating tension and compression of the edge piles, combined with shear-moment loading. The resulting stiffness reduction of the cracked under tension piles leads to load redistribution towards the stiffer compressed piles, preventing plastic hinging of the weaker piles (under tension). These findings are consistent with post-earthquake in-situ testing, qualitatively verifying the numerical analysis technique. Subsequently, alternative foundation concepts are explored, starting with the pilecap of the original configuration acting as a shallow footing, provoking nonlinear rocking response. It is shown that soil yielding acts as a “fuse”, preventing collapse at the cost of increased settlements and limited residual foundation rotation. The benefits and limitations of such a shift towards nonlinear soil–foundation response are further explored, studying four intermediate foundation schemes. Show more
Journal / seriesSoils and Foundations
Pages / Article No.
SubjectKobe earthquake; Bridge collapse; Nonlinear analysis; Soil-structure interaction
Organisational unit02607 - Institut für Geotechnik / Institute for Geotechnical Engineering
09569 - Anastasopoulos, Ioannis / Anastasopoulos, Ioannis
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