Alphatecs Presenting at the Canadian Geotechnical Conference

72nd Canadian Geotechnical Conference

St. John's, Newfoundland, Canada

September 29 - October 2, 2019

A Novel Approach for Performance-Based Design of Piles and Shafts under Liquefaction using Coupled Nonlinear Soil-Structure Interaction Analysis

Sasan Iranpour, Ph.D., P.Eng.

One of the design challenges for bridges, buildings, port and marine structures is lateral spreading and ground liquefaction. There exist various simplified methods to study the behavior of structures in such soil conditions. However, in cases with large soil forces and movements, a plastic hinge may be generated in the structure, which adds to the complexity of the system. To avoid this, the general practice is to increase the capacity of the pile and shaft, which in turn increases the soil loads. In some cases, the soil loads increase at even a faster rate than the pile capacity, which ultimately makes it impossible to design a conventional structure based on the deterministic approaches provided by design standards.

Using the complex interaction of all stresses generated in the structure, this study presents a simplified approach based on a coupled nonlinear analysis of both the soil and the structure. It is demonstrated that when the pile enters the nonlinear range of the material response, it puts a limit on the loads that can be generated in the pile. This helps the designer move beyond the boundaries of traditional force-based design method, and use the robust performance-based design approach, where a more accurate response of the system is taken into consideration.