Reliability Analysis for Differential Settlement of Shallow Bridge Foundations in Cohesionless Soils

Settlement of structures built on soils is a subject of considerable interest to practicing engineers since excessive settlement is one of the most important problems in soil mechanics and can lead to serviceability problems or even failure states in the structure’s foundations. A reliability-based approach can be applied for designing shallow bridge foundations considering the knowledge of the distribution of differential settlement between footings. The objective of this study is to develop the methodology for risk analysis procedures of shallow foundations. In which, it requires the development of the reliability models that can be applied to shallow foundations and involves the establishment of serviceability limit state functions. The most important part of this study is the development of statistical models for differential settlements of shallow foundations in cohesionless soils by the Monte Carlo simulations technique. The study verifies the most accurate two settlement prediction methods for calculating immediate settlement of spread footings for each site by using compiled field data from research projects. Vertical settlements were measured on 20 footings (yielding 10 measurements of differential settlement) from seven bridges in the Northeast US and one bridge in Ohio. Reliability indices are determined for differential settlement of the spread footings assigned in this study.