Improved Method for the Seismic Design of Anchored Steel Sheet Pile Walls

This paper describes a new pseudostatic approach for an efficient seismic design of anchored steel sheet pile (ASSP) walls supported by shallow passive anchorages. As for other retaining structures, energy dissipation during strong earthquakes leading to reduced inertia forces can be achieved by allowing the activation of ductile plastic mechanisms. To this end, a robust method is required to identify all the possible yielding mechanisms and to guarantee the desired strength hierarchy. It is shown that dissipative mechanisms for ASSP walls correspond either to the local attainment of the soil shear strength in the supporting soil and around the anchor, or in the activation of a log-spiral global failure surface. A new limit equilibrium method is proposed to compute the critical acceleration of the system, corresponding to the actual mobilization of its strength, and the maximum internal forces in the structural members. Theoretical findings are validated against both existing dynamic centrifuge data and the results of original pseudostatic and fully dynamic numerical analyses

Theoretical framework for the seismic design of anchored steel sheet pile walls

Anchored Steel Sheet Pile (ASSP) walls are widely used as retaining structures in wharves and quays as an alternative to gravity concrete walls due to their ease of installation. Their seismic design is based on conventional pseudo-static approaches, often leading to uneconomic solution in high seismic areas. This paper addresses the dynamic behaviour of ASSP walls retaining dry cohesionless backfills, in order to investigate the possible failure mechanisms of the soil-wall system and the resulting permanent displacements. Simple limit equilibrium methods are developed to predict the internal forces in the structural members and to compute the critical acceleration of the soil-wall system, corresponding to which the strength of the soil is completely mobilised. Theoretical predictions are compared with the results of an extensive numerical study, including both pseudo-static and dynamic analyses. The key role of the critical acceleration for the structural and the geotechnical design of ASSP walls is highlighted, controlling both the maximum internal forces and the magnitude and trend of displacements

Physical modelling of anchored steel sheet pile walls under seismic actions

This paper describes an experimental investigation of the behaviour of anchored Steel Sheet Pile (SSP) walls under seismic actions. Dynamic centrifuge tests on reduced scale models of anchored SSP walls in dry medium dense sand were carried out on the Turner beam centrifuge at the Schofield Centre, Cambridge University. In order to be able to observe the failure mechanism, the tests were carried out in a rigid container with a Perspex viewing window. A layer of Duxseal© was placed on the lateral boundaries of the container to minimise reflections. The amplitude of the earthquakes was increased up to a peak acceleration significantly higher than critical, in order to trigger failure of the soil-wall-anchor system. In this paper the experimental results are presented in terms of bending moments along the retaining wall, anchor forces and displacement fields of both the retaining wall and the soil behind it. Displacement field and hence soil strains were obtained by particle image velocimetry analyses