Date of Graduation

12-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Dennis, Norman D. Jr.

Committee Member

Coffman, Richard A.

Second Committee Member

Bernhardt, Michelle L.

Third Committee Member

Pohl, Edward A.

Keywords

Bayesian Updating; Bridge Foundations; Deep Foundations; Driven Piles; Load and Resistance Factor Design (LRFD); Reliability Analysis in Geotechnical Engineering; Reliability-Based Design and Acceptance Protocol for Driven Piles

Abstract

The current use of the Arkansas Standard Specifications for Highway Construction Manuals (2003, 2014) for driven pile foundations faces various limitations which result in designs of questionable reliability. These specifications are based on the Allowable Stress Design method (ASD), cover a wide range of uncertainties, do not take into account pile and soil types, and were developed for general use. To overcome these challenges it is deemed necessary to develop a new design and acceptance protocol for driven piles. This new protocol incorporates locally calibrated RLFD resistance factors for accounting for local design and construction experiences and practices, as well as specific soil conditions and pile types.

In that perspective, this dissertation focuses on the design and acceptance of driven pile foundations (predominately for bridge projects) using an LRFD protocol. A great deal of insight is gained into the factors that contribute to the performance of deep foundations by conducting an extensive literature review. The research assembled a relatively large database of pile load tests where both static and dynamic load testing was performed and sufficient soils information existed to perform static design calculations. A MATLAB® based program was developed to use the information contained in the database to compute resistance factors for driven piles using the First Order Second Moment Method (FOSM), Improved FOSM, the First Order Reliability Method (FORM), and Monte Carlo Simulations (MCS). The research also addressed a technique to update resistance factors using Bayesian techniques when new load tests are added to the database. More importantly the dissertation formulated a design and acceptance protocol that seeks to unify the level of reliability for deep foundations through both the design and construction phases.

As a verification mechanism to the developed design and acceptance protocol, a full-scale pile load testing program was recommended. The testing program would be composed of ten driven piles that had been dynamically and statically load tested. It was found that, for the same required reliability level, acceptance criteria could be lowered if more piles are tested on a jobsite. Subsequently, a non-contact instrument¬-such as Pile Driving Monitoring device-is recommended to verify in situ pile capacity of each and every pile on construction site. The results from in situ pile capacity verification could be employed to update the calibrated resistance factors and to refine future designs.

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