Seismic displacement-based design of embedded retaining structures

The paper presents an application of the seismic design method named “Direct Displacement Based Design” (DDBD), first introduced in 1990s in the field of earthquake structural engineering, and gaining due attention in the recent years. The method can be applied to a wide range of structural types, including geotechnical structures. The fundamental philosophy behind DDBD is that structures should be designed to achieve a specified performance level under a certain seismic intensity. In the paper, DDBD is described with considerable discussion on its applicability to flexible earth retaining structures in coarse grained-soils. Particular attention is given to the evaluation of the equivalent damping ratio of the wall/soil system, since it sensibly affects the results of the procedure. A simplification of the design process is proposed in order to provide a seismic demand curve, in terms of active/passive thrust, which is dependent on the system ductility. A numerical example of application of the method is provided in the paper.