Sri Sritharan Department of Civil, Construction & Evnironmental Engineering
Wilkinson Chair Professor in Engineering (515)294-5238 |


Connection Details and Field Implementation of UHPC Piles - Phase II

Principal Investigator(s): Sri Sritharan
Sponsor(s): Iowa Department of Transportation
Iowa Highway Research Board (IHRB)
Start Date: 12/15/2009
End Date: 10/31/2015

Project Description:

Phase I of the research project entitled "Use of Ultra-High Performance Concrete in Geotechnical and Substructure Applications" was executed as part of the seed funding program for high-risk research ideas initiated by the Iowa Highway Research Board in 2006. The project, which was motivated by American Association of State Highway and Transportation Officials (AASHTO) call for the critical need to design durable bridges and infrastructures that can last for a minimum of 75 years with minimal maintenance, was successfully completed and the final report was presented in December 2008. In addition to the funding from Iowa Highway research Board (IHRB), the project team received in-kind contributions from the industry (namely Lafarge North America; Coreslab, Omaha; Iowa DOT; and Cramers and Associates) and accomplished the following major tasks:

(1) Designed a H-shaped cost-effective, easily constructible UHPC pile
(2) Verified the moment-curvature response of the UHPC pile cross-section through large-scale testing
(3) Performed full-scale vertical and lateral load tests on UHPC piles driven into the ground at a bridge site in Iowa

The results of the research project was very well received by researchers and practising engineers in the deep foundation community, and enabled the graduate student engaged in the project to receive major national student awards as should be expected for high-risk research projects. Research outcomes of Phase I of this project revealed several benefits of the UHPC pile including reduced risk of damage during driving, drivability with a greater range of hammers and strokes, possibility of driving the pile without any cushion, use of the existing equipment for pile handling and driving, and reduced maintenance costs compared to steel and concrete pile due to enhanced durability of UHPC. However, the research conducted in this phase did not address several other issues that need attention prior to developing a full implementation procedure for UHPC piles in Iowa and other states. With input from Technical Advisory Committee (TAC) of the Phase I study, the following tasks were identified for the future direction of the project:

(1) Establish connection details to extend piles in the field
(2) Establish connection details between the pile and pile cap and between the pile and bridge abutment
(3) Install a UHPC pile as part of a bridge foundation to compare its behavior under long-term loading condition to the behavior of steel H piles under field conditions
(4) Develop a preliminary geotechnical design methodology (displacement vs. non-displacement pile design)
(5) Drive UHPC piles in different soil conditions in Iowa to establish a driving database and finalize the pile design methodology in accordance with Load and Resistance Factor Design (LRFD)
(6) Evaluate drivability of UHPC piles into bed rock
(7) Conduct vertical and lateral load tests in different soil conditions in Iowa, and
(8) evaluate performance of battered UHPC piles

To expedite the research and implementation of UHPC piles in bridge foundation design practice, we propose to conduct Phase II of the study consisting of Tasks 1 - 4 described above. This proposal was selected for funding in 2009-2010. Described in this document is our plan to execute Phase II of the project which will focus on the connection details and field implementation of UHPC piles.