Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Abstract

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. This paper will present results from a Pile Demonstration Program (PDP) that was conducted as part of the bridge replacement project, discuss the various aspects of the seismic design and analysis, and describe how those data were applied to optimize foundation design. The PDP included dynamic monitoring, static load tests and Statnamic load tests at several locations, to evaluate: (i) the pile driveability and associated parameters necessary for dynamic analysis; and (ii) the ultimate skin friction and end bearing values for design. The PDP provided a basis for eliminating static load tests during construction and construction quality control, and for evaluating potential settlement of the existing bridge. Although the seismicity of the region is low, considering the importance of this bridge and the consequences of potential damage during an earthquake, seismic issues were addressed thoroughly in the design of the new structure, including: (i) development of design spectra based on site-specific seismic hazard and ground motion analyses; (ii) implications of the complex soil profile and potential scour on the dynamic response of the foundations; (iii) Soil-Structure Interaction (SSI) analyses for the various foundation alternatives; and (iv) evaluation of the significance of the kinematic SSI effect on the piles. The presented case study proves how results of a pile demonstration program and extensive seismic studies can enable significant optimization of the foundation design and cost savings, and provide significant quality control during construction.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

Foundation Optimization and Design for Replacement of the Woodrow Wilson Bridge

New York, New York

The new Woodrow Wilson Bridge (WWB) will replace the existing bridge over the Potomac River to connect Alexandria, Virginia to Prince Georges County, Maryland. The new WWB will extend approximately 1.1 miles across the river, with a 367-ft long bascule span in the main river channel where the water depth is about 36 ft. The subsurface soil profile consists of up to 50 ft of a soft organic silty clay layer that is very vulnerable to scour, underlain by a deep deposit of hard sandy clay. This paper will present results from a Pile Demonstration Program (PDP) that was conducted as part of the bridge replacement project, discuss the various aspects of the seismic design and analysis, and describe how those data were applied to optimize foundation design. The PDP included dynamic monitoring, static load tests and Statnamic load tests at several locations, to evaluate: (i) the pile driveability and associated parameters necessary for dynamic analysis; and (ii) the ultimate skin friction and end bearing values for design. The PDP provided a basis for eliminating static load tests during construction and construction quality control, and for evaluating potential settlement of the existing bridge. Although the seismicity of the region is low, considering the importance of this bridge and the consequences of potential damage during an earthquake, seismic issues were addressed thoroughly in the design of the new structure, including: (i) development of design spectra based on site-specific seismic hazard and ground motion analyses; (ii) implications of the complex soil profile and potential scour on the dynamic response of the foundations; (iii) Soil-Structure Interaction (SSI) analyses for the various foundation alternatives; and (iv) evaluation of the significance of the kinematic SSI effect on the piles. The presented case study proves how results of a pile demonstration program and extensive seismic studies can enable significant optimization of the foundation design and cost savings, and provide significant quality control during construction.