Integral Abutment Details for ABC Projects, Phase II

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Final Report

ABC-UTC Guideline for Integral Abutment Details for ABC Projects, Phase II

Background:
Reduction of road closure times, traffic disruption and user costs, in addition to improvements in construction quality utilizing prefabricated elements, are all qualities of Accelerated Bridge Construction (ABC) that transportation organizations throughout the country find attractive.  Taking ABC a step further requires finding means and methods to improve the quality, performance and durability of bridges constructed using ABC.  Implementation of quality semi-integral and integral abutment designs in ABC projects is one example.  These types of abutments have been used for many years in traditional construction but have seen very limited use in ABC projects.  The purpose of this research is to expand the development of integral abutment designs for ABC projects utilizing grouted rebar couplers, and other alternative methods, and evaluate the strength and durability performance of the details in the laboratory.

Objectives:
Accelerated bridge construction technology, initially reserved for routes with large AADT’s and/or critical thoroughfares, has significantly improved and increased in popularity.  As a result, the benefits and economics of these techniques have gained traction in nearly all avenues of bridge replacement.  However, one area of ABC technology in need of additional research is the development of integral abutment designs that function as intended while also allowing for rapid, efficient construction.  These details will allow the ABC product, which is already of high quality and constructed under exceptional quality control, to further extend its service life and reduce maintenance cost by eliminating the expansion joints at the ends of the bridge.  To fully understand the strength, durability, and construction limitations of an ABC integral abutment connection, and to meet the complete objectives of this work, a three-step process will be required.  In short, the three steps include: 1) development of design details for integral abutments for ABC projects, 2) evaluation of the strength and durability characteristics of the integral abutment details, and 3) laboratory testing of two or three of the most promising prototype designs.

Scope:
The proposed research will develop integral abutment details utilizing different connection details (some modified from Phase I as well as other new details) for use in ABC projects and conduct laboratory testing on three of the most promising concepts.  The following tasks will be performed to achieve the project goals.

  • Task 1 – A detailed review of scientific papers focusing on previous uses of integral abutments in ABC projects will be conducted.  In addition, all relevant developments and design details/requirements for integral abutments used in typical bridge construction will be collected and examined.
  • Task 2 – Based on the outcome of Task 1, several details for an integral abutment will be developed for review by the TAC, beginning with the following: 1) modified grouted rebar coupler connection with reduced number of coupled bars; 2) modified HP coupler connection with increased moment capacity ; 3) joint detail utilizing ultra-high performance concrete (UHPC) for the connection grout detail.  Building upon comments from the TAC and contractors familiar with ABC practices/projects, these conceptual designs will be refined, modified and/or eliminated, if needed.  Once final designs of the conceptual integral abutment details are drafted, the TAC committee will select three of the most promising concepts for evaluation and testing in the laboratory, see Task 4.
  • Task 3 – As in Phase I, this project will commence further testing and evaluation of the strength and durability characteristics of integral abutment connection in ABC projects, see Task 4.  Given the accelerated pace of these ABC projects, construction defects and errors in tolerance are sometimes unavoidable.  Therefore, Task 3 will investigate and evaluate the constructability aspects of the connection details during the specimen fabrication and erection process.
  • Task 4 – Using the results from Task 3, the integral abutment detail(s) selected in Task 2 will be fabricated in the laboratory for full-scale testing and evaluation.  Laboratory testing will resolve to determine the following: 1) constructability (tolerance) issues, if any, related to the integral abutment joint construction, 2) the structural performance of the integral abutment in terms of strength, and 3) the structural performance of the integral abutment in terms of durability.
  • Task 5 – A final report will be developed that documents the entire project with a special emphasis on the results of Task 4.  More importantly, recommendations for integral abutment details for use in ABC projects will be made.

Research Team:
Principal Investigator:  Travis Hosteng
Co-Principal Investigator:  Dr. Behrouz Shafei
Research Assistant:  Austin DeJong

Previous Progress Reports: