Material Design and Structural Configuration of Link Slabs for ABC Applications

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Final Report

Background:
Application of ABC techniques has been significantly increased over the past ten years owing to the unique advantages of the bridges built with ABC, including short duration of construction and high quality of prefabricated bridge elements. By decreasing the construction time from months to days, the ABC techniques contribute to the safety of work zones by minimizing the on-site activities that can cause accidents for construction workers and motorists. On the other hand, with improved product quality, which can be achieved in prefabricated bridge elements built under controlled environmental conditions, the durability and performance of bridges are enhanced during the design life. Despite major advances in the design and construction of the main bridge elements for ABC applications, the joints that connect the bridge spans are still in need of improvement and further investigation. The expansion joints play a critical role in accommodating unrestrained deformations of adjacent spans due to thermal expansion and traffic loads. The existing joints, however, deteriorate rapidly and require major maintenance efforts. To address this issue, the idea of using link slabs to eliminate the joints has been explored to a limited extent for conventional bridges. There is, however, no study available in the literature on how link slabs can be properly utilized for ABC applications.

Objective:
The proposed research project aims to investigate various aspects of this subject through a comprehensive set of experimental tests and numerical simulations.

Scope:
The following tasks will be performed to achieve the project goals.

  • Task 1 – Literature Review – As the first task of this project, the research team will compile all related information available in journals, conference proceedings, and technical reports in a concise summary usable by the involved researchers and engineers. The main objective of this task is to obtain a comprehensive understanding of the existing practices for the construction of jointless bridges with a special focus on ABC applications.
  • Task 2 – Experimental Tests on Link Slab Materials – To evaluate if the proposed material is capable of providing a satisfactory performance, dog-bone shaped specimens are constructed and tested under direct tension. The outcome of this test provides the stress-strain relationship further to the patterns of crack initiation and development. In addition to stress-strain characteristics, the criteria to choose appropriate materials for reinforcement will be developed through this task.
  • Task 3 – Experimental Tests on Bridge Joints – To investigate the performance of the link slabs constructed with materials identified in the previous task, full-scale experimental tests will be conducted. The test model is expected to be a single girder system with necessary support conditions. To understand the structural behavior of the link slab in the real condition, two loading cases will be applied:  (1) with constantly increasing static load to obtain load-deformation response and (2) with cyclic loads to examine the long-term performance of the system under traffic loads. The full-scale experimental tests are also used to evaluate some of the current construction practices, especially in terms of debonded length.
  • Task 4 – Parametric Studies and Design Recommendations – Based on the outcome of the previous tasks, a set of numerical simulations will be performed to develop the models that can properly capture the structural response of the link slabs in various structural configurations and loading cases. The obtained information from experimental tests and parametric studies will be utilized to examine the current design recommendations and make the required modifications. A special effort will be made to adjust the design guidelines based on the practical considerations demanded by ABC applications.
  • Task 5 – Final Report – A detailed final report will be prepared to document the activities of the project further to all the main observations and findings.

Research Team:
Principal Investigators: Dr. Behrouz Shafei, Dr. Brent Phares, and Dr. Peter Taylor
Research Assistant:

Previous Progress Reports: