The overall goal of this research is to improve the seismic safety and resiliency of highway bridges in the Pacific Northwest during earthquakes. Past earthquakes have shown that liquefaction-induced lateral spreading can be a major cause of collapse for pile foundations. Bridge engineers generally agree that pile foundations must be designed for: (a) lateral spreading loads caused by liquefaction of soils adjacent to piles, and (b) inertial loads during shaking resulting from the superstructure mass. However, there is no consensus in design codes and standards on how to combine these inertial and kinematic loads, as evidenced by varying recommendations from transportation agencies including AASHTO, ODOT, WSDOT, and Caltrans. The absence of consensus in design codes and standards has resulted in significant confusion among foundation designers. Consequently, there is a pressing need to develop design guidelines for piles in laterally spreading ground that are practical and supported by experimental data.

The objective of this project is to develop practical and evidence-based methodologies to predict satisfactory versus unsatisfactory (collapse) performance of bridge foundations subjected to lateral spreading during earthquakes. To achieve this objective, we will use data from a 1-g shake table test conducted at UC San Diego’s Powell facility by Professor Elgamal and his team (Ebeido and Elgamal 2019). Professor Elgamal has kindly shared the shake table test data with the PI for this research effort. This shake table test is distinct in that it resulted in the collapse of the pile foundation toward the end of shaking. This offers a unique opportunity to develop design procedures capable of predicting such failures. Numerical models will be calibrated and validated using the shake table test data and will subsequently be used in a parametric study to provide practice-oriented design recommendations.