Foundation Analysis First Street Viaduct
over the Los Angeles River
City of Los Angeles, California

Hushmand Associates, Inc. (HAI) provided geotechnical design parameters (settlements, bearing capacities, and stiffness coefficients) and recommendations for seismic retrofit of the existing First Street Viaduct over Los Angeles River located in the City of Los Angeles, California, and for design and construction of an approximately new 24-foot wide bridge parallel and adjacent to the existing one, based on the results of field and laboratory tests performed by others and the previous geotechnical investigations at the site.

HAI's scope of services for this project consisted of the following tasks: Generate site horizontal Peak Bedrock Acceleration (PBA) and Acceleration Response Spectra (ARS); Develop site soil profiles (layering and properties) using boring logs and blow counts; Evaluate bearing capacities and settlements for spread footings; Provide axial and lateral capacities for deep foundations; Provide elastic spring constants for spread footings, single piles, and pile groups; Provide elastic spring constants for abutment walls; Generate nonlinear P-Y curves for pier walls; and Prepare reports and attend meetings. HAI is currently providing monitoring and data analysis during Static Axial Tensile Load Tests performed by the project contractor in general accordance with Caltrans foundation Manual (Chapter 8) and ASTM D3689-07 (Standard Test Methods for Deep Foundations Under Static Axial Tensile Load) as well as Pile Dynamic Analysis (PDA) tests performed on the same pile. The PDA test results were used in CAPWAP analysis to compute frictional resistance portion of the axial compressive capacity of the pile. Results of the static axial tensile pile load and PDA tests were processed and compared against each other to calibrate the PDA method, which is currently used to measure axial tensile capacity of more piles during construction. HAI is providing onsite observations during PDA tests performed at various piles in order to evaluate in-situ pile capacities.