Rapid Repair and Retrofit of Timber Piles Using UHPC

Link to the Latest: September 2020 progress Report

Background:
One of bridge substructure system utilizes a pier consists of a beam supported over timber piles. This substructure system is common practice in county bridges. Many reasons can lead to the deterioration of these timber piles can deteriorate over an extended period of time such as biological damage caused by fungi, termites, powderpost beetle, carpenter ants, and bacteria or physical damage due to floating in water, overload, failure of adjacent piles, and firs. Replacing the damaged timber pile may be considered an obvious option to address the damage; however, the cost of an effective repair and retrofitting of timber piles can be much cheaper. Different repair and retrofit techniques are available for the timber piles and some of the retrofit options failed to result in the expected performance levels. The best repair technique should restore the load carrying-capacity of the timber piles and at the same time should be cost-effective. The superior mechanical properties of UHPC, such as high compressive strength and high tensile strength make this material a perfect solution to repair and retrofit timber piles. This project proposes the use UHPC as repair and retrofit material for timber piles, however, many research questions should be answered such as the bond strength between timber and UHPC, the surface preparation for timber piles to enhance the bond strength with UHPC, the effect of UHPC thickness of repair/retrofit. These questions, among others, will be answered under this project.

Objective:

1-         Studying the bond strength between timber and UHPC as repair/retrofit material;

2-         Defining the best surface preparation for timber piles in order to enhance the bond strength;

3-         Studying the load-carrying mechanism of timber piles repaired or retrofitted using UHPC;

4-         Conducting small scale testing to study the bond strength and load-carrying mechanism between timber and UHPC;

5-         Conducting large scale component testing of timber piles repaired/retrofitted using UHPC under realistic axial and lateral loading schemes;

6-         Studying repair methods for in-service weathered piles; and

7-         Developing detailed finite element models for both small scale material testing and large scale component testing for better understanding of the local and global behavior of timber piles repaired/retrofitted using UHPC.

Scope:

An overview of the study tasks is given below.

  • Task 1–  Conducting literature review on current practice of repair and retrofit of timber piles
    • In this task, a comprehensive literature review will be conducted including the current repair and retrofit practices for timber piles, bond strength between timber piles and repair materials, and load carrying capacity of repaired/retrofitted timber piles.
  • Task 2– Small scale experimental work
    • In this task, experimental work will be conducted on small scale level specimens to study the bond strength of UHPC as repair/retrofit material for timber with different surface preparation. In addition, compressive tests will be conducted on cylindrical shape timber with UHPC shell to study the load carrying mechanism between timber piles and UHPC
  • Task 3– Large scale experimental work
    • In this task, full-scale specimens of repaired/retrofitted timber piles will be tested under axial and lateral load schemes.
  • Task 4–  Numerical model verification through finite element analysis
    • In this task, numerical models will be developed to calibrate the test results from Task 2 and Task 3 to better understand
  • Task 5–  Final Report
    • In this Task, Full assessment of the findings from Task 1 throughout Task 4 will be conducted and a report will be published including design recommendations of repairing and retrofitting timber piles using UHPC.

Research Team:
Principal Investigator:  Dr. Islam M. Mantawy
Co-Principal Investigator: Dr. Atorod Azizinamini
Research Assistant: Carlos Sosa

Previous Progress Reports: