Project 2d: Calibration of Load and Resistance Factors in LRFD Foundation Design Specifications

Status

Sequential Number

Identification Number

Matching Research Agency

Missouri Department of Transportation (MoDOT) and Missouri University of Science & Technology (Missouri S&T)

Principal Investigator

Student Involvement

Project Objective

The objectives of this project include:

1)  Develop a new design methodology for drilled shaft foundations to allow for limited displacements under gravity loads,

2)   Analyze representative highway bridges to understand the effect of foundation displacements on the design loads and strength requirements of the bridge superstructure, and

3)  Calibrate the load and resistance factors in LRFD design specifications.

An additional objective of this project is to provide a mechanism for the Structures Thrust Area to interact and collaborate with the Geotechnical Thrust Area. The PI of this project will serve as a liaison between the two thrust areas.

Project Abstract

The AASHTO LRFD Design Specifications for drilled shaft foundations are yet to be calibrated with test data in Missouri sites. Foundation is a critical part of a bridge system. It not only affects the stability of the overall system, but also constitutes a significant portion of the bridge construction costs. Therefore, better calibrations with field tests are imperative. Additionally, foundation design calibrations warrant the consideration of a bridge system and thus require a close collaboration between geotechnical and structural engineering. Typical bridges will be analyzed to understand the demand (load factor) on drilled shaft foundations and the required strength (resistance factor) given a certain allowable displacement. Both load and resistance factors will be calibrated with the Missouri environment and traffic condition using a reliability-based approach. 

Task Description

N/A

Anticipated Benefits

The anticipated deliverables from this project include:

• A rational framework for the development of performance-based design methodology with permissible foundation displacements, and

• New LRFD Specifications that have been calibrated with test data in Missouri.

Milestones

Relationship to other Research/Projects

A project under the Missouri S&T-UMC-UMKC MoDOT Structures Program Initiative.

Technology Transfer Activities

The technology transfer activities will include a final research report and dissemination of the findings through a national conference via technical presentation and publication(s).

Transportation Research Board Keywords

Performance-based design, LRFD specifications, drilled shaft foundation, load and resistance factor calibration.