Structural Analysis of Liquefaction Using SAP2000: Integrated Deformation-Based Downdrag Analysis

The Municipality of Skagway (MOS) undertook the Ore Peninsula Redevelopment project as part of ongoing efforts to revitalize the Skagway waterfront with the installation of a floating cruise dock, an industrial wharf, and a Roll-On Roll-Off (RORO) dock. The seismic liquefaction potential of the soils at the project site created the design challenge of integrating downdrag loading into a global structural model. This paper describes the Integrated Deformation-Based Downdrag Analysis (IDDA) method, which represents a further development of the deformation-based techniques used during the Ore Peninsula Redevelopment project. Examples of implementation using SAP2000 are included, showing potential IDDA results in different soil conditions, as well as a comparison to traditional force-based downdrag methods described in design codes.