Jerko Kocijan Presented on the Efficacy of the Cone Penetration Test in Estimating the Capacity of Driven Piles at The Western Bridge Engineers’ Seminar
Jerko Kocijan, Ph.D., P.E., G.E., M.ASCE (California) presented "Axial Pile Capacity Predictions using CPT Direct Method and Comparison with PDA Test Results" at The Western Bridge Engineers' Virtual Seminar in at 11 a.m. PDT on September 13, 2021.
Jerko's co-presenters were Farid Motamed, Fugro USA Land, Inc.; Hossein Rashidi, EarthSpectives, Inc.; Samar Saad, OC405 Partners; Medji Sama, Fugro USA Land, Inc.; Curt Scheyhing, Group Delta Consultants, Inc.; and Amiri Sharid, Caltrans.
Jerko Kocijan is a Principal Engineer based in California with more than 15 years of experience focused on nearshore infrastructures and energy projects, with project components ranging from aspects of site characterization, seismic hazard assessment, geotechnical foundation feasibility assessments, and development of final designs. His expertise also includes advanced soil-structure assessment using numerical modeling. As part of the value creation approach to design, he is experienced in cost-benefit foundation system selection approach which is based on stakeholder input, subsurface risk assessment, risk mitigation and risk management, and use of latest ground modification and ground improvement techniques.
The Western Bridge Engineers' Seminar is a biennial cooperative effort by the Federal Highway Administration and the Transportation departments of Alaska, Arizona, California, Idaho, Nevada, Oregon, and Washington. Its purpose is to facilitate the exchange of information between government agencies, consultants, contractors, educators, and suppliers on subjects of current interest to the design, construction, and maintenance of bridges.
Axial Pile Capacity Predictions using CPT Direct Method and Comparison with PDA Test Results
Prediction of axial pile capacity and confirmation of the predicted values by field testing are key elements of geotechnical design of bridge pile foundations. Construction and performance challenges can occur when field exploration or subsurface interpretation issues result in overestimation of the capacities. Similarly, underestimating pile capacities will result in schedule delays and additional cost for more or longer piles. An optimum methodology for estimating axial pile capacity would satisfy two criteria: repeatability of predictions, and consistent track record of predictions matching the results of field verification tests. The cone penetration test (CPT), with its nearly continuous information on the soil profile, is a near perfect subsurface characterization tool for use in estimating capacity of driven piles. The CPT is like a small scale instrumented driven (or pushed) pile of small diameter. Data collected by the CPT include tip resistance and sleeve friction. Historically, as the use of CPT grew, several methods were developed to predict end bearing and shaft friction of driven piles capacity directly from CPT field data. While previous non-CPT methods required multiple steps, including identifying soil type, selecting soil strength parameters using field and laboratory testing, and then performing calculations, CPT based methods effectively convert CPT data into predicted axial capacity through an Excel spreadsheet. Use of CPT improves repeatability of predictions, and significantly reduces the dependence on individual designers' interpretation of subsurface conditions and of soil strength parameters for use in calculations. I-405 Improvement Design-Build Project in Southern California involves construction of about 20 new bridges or bridge widenings and dozens of new retaining walls supported on driven piles. A CPT direct method was used to predict axial pile capacities during the project design stage. The presentation will present a general description of typical subsurface conditions and design approach for prediction of axial pile capacity using direct CPT methodology. The design predictions will be compared with the results of the PDA tests, providing discussion on the ability of the CPT direct method to predict pile capacity. The majority of the piles evaluated are 24‑inch open ended steel pipe piles.
About the event: Western Bridge Engineers Seminar
Learn more about Jerko: Jerko Kocijan – LinkedIn