Ground motion scaling for the assessment of the seismic response of a diaphragm wall

Nonlinear finite element analysis represents an advanced numerical approach to study the dynamic performance of geotechnical structures subjected to earthquakes. The approach requires the use of sophisticated soil constitutive assumptions and the correct definition of the bedrock input motions, opportunely selected to be representative of the site seismic hazard. Different input motion scaling methods have been proposed to minimise the bias and reduce the number of simulations needed to obtain statistically stable and robust results. These scaling methods have mainly been adopted in structural engineering, but their application in geotechnical earthquake engineering problems is still limited. The paper investigates the effect of five different earthquake scaling/matching strategies on the nonlinear dynamic response of an anchored diaphragm wall supporting a deep excavation in Boston Blue Clay. Two seismic intensity levels are considered. The results are interpreted, for each scaling/matching technique, in terms of seismic induced maximum horizontal displacements of the wall.