Performance-based seismic design of flexible earth-retaining structures

Performance-based design differs from conventional design in that target performance is clearly stated and explicitly checked. A faithful application of this design criterion requires refined analysis methods to quantify performance and explicit consideration of all relevant uncertainties. The paper presents a design procedure that satisfies these requirements. The procedure is presented with reference to flexible earth-retaining diaphragm walls, which represent a challenging test for such a procedure given the influence of dynamic soilstructure interaction on the response in terms of internal forces and deformations. In order to remain affordable and feasible in practice, yet accounting for the aforementioned sources of uncertainties and the important physical aspects of the system response, the procedure is based on small-sample Monte Carlo simulation and a nonlinear dynamic model of such soil-wall systems developed recently. The latter strikes a balance between model setup and analysis time on one hand and accuracy on the other, being capable of re-producing the cumulative build up of soil pressure in cyclic deformation and the accumulation of permanent displacement of the wall with an overall modeling and analysis effort in the order of few tens of minutes. Performance is measured in terms of mean annual rate of exceedance curves from which design values are obtained.