Reliability analysis of shallow foundations in reference to design codes development

Abstract In this study, FORM analysis is carried out for shallow foundation of a typical building in order to evaluate relative magnitude of uncertainties involved in the force and the resistance sides. The distinguished feature of this study is to take into account the uncertainty of the earthquake force as much as possible. Tthis is because, the seismic design dominates major part of structural design in Japan, and without referring to this problem, no useful information of practical value is gained. The results of the FORM analysis exhibited the reliability index values between 2.0 to 3.5, which is considered to be in a reasonable range. Since the 50 year maximum earthquake force is considered in the reliability calculation, calculated reliability index values are for the period of 50 years. The sensitivity factor obtained in a case more realistic ground variability is taken into account exhibited values not very different from those obtained in the upper structures.