Prefabricated Barrier System Utilizing UHPC Connections

Link to the latest: September 2020 Progress report

Background:
Barriers are one of the most important safety features in bridge construction and their main function is to keep vehicles within roadways and redirect errant vehicles passing the bridge. The philosophy of barrier design is to have a sufficiently resistant deck to force the yield line failure pattern to remain in the barrier. Therefore, the deck overhang is designed to provide a flexural resistance, acting coincidence with the tensile force, more than flexural resistance of barrier about the longitudinal axis of the bridge. One durability issue regarding cast-in-place (CIP) barriers is the early-age cracking due to temperature gradients and curing conditions which can subject them to excessive risk of corrosion, leading to costly repair projects. This undesired phenomenon can be avoided by using high-quality prefabricated barriers which can significantly reduce on-site construction time and enhances work zone safety. However, connecting prefabricated barriers to the structure may be challenging. Several attempts were taken place to develop prefabricated barriers with connection to the bridge deck using post-tensioned thread rods and stainless steel bars. However, those connections are associated with higher cost and durability issues. A new prefabricated barrier system utilizing UHPC connection to deck overhangs is proposed under this project.  A single-slope prefabricated barrier with grooves will be connected to deck overhang with dowels extended vertically from its end. The grooves in addition to 1 in. leveling pad will be filled using UHPC to connect the prefabricated barrier to bridge deck overhang. The use of UHPC allows for shorter development length of overhang extended dowels resulting in easy erection and simplification in reinforcement details of the barrier itself. Under this project, component and large scale testing will be conducted along with extensive finite element models to ensure that the proposed prefabricated barrier system with UHPC connections meets TL-4 requirements.

Objective:

1- Development of new connections utilizing UHPC to connect prefabricated barriers to bridge deck considering geometry and fit-up issues;

2- Conducting detailed finite element modeling on the proposed barrier system and connections;

3- Conducting a proof of concept experimental work on component test for the proposed prefabricated barriers with UHPC connections;

4- Conducting a proof of concept experimental work on large test for the proposed prefabricated barriers with UHPC connections;

5- Assessment of the performance of the prefabricated barriers with UHPC connections compared to the most common barrier systems; and

6- Developing detailed finite element models for the proposed prefabricated barriers with UHPC connections for better understanding of system performance, therefore, extending the study to analyze other specimens which will not be possibly tested.

Scope:
An overview of the study tasks is given below.

  • Task 1 –  Development of new connections using UHPC for Prefabricated Barrier Systems
    • In this task, a conceptual approach will be carried out to propose a different connections between prefabricated barriers and bridge deck. An example of one connection is illustrated in Figure 5.
  • Task 2– Preliminarily Finite Element Modeling for the Proposed Prefabricated Barrier System
    • In this task, numerical investigation using finite element analysis will be conducted on the proposed prefabricated barrier with UHPC connection to verify that the proposed barrier complies with TL-4 requirement. In this task, the design of test specimens will be finalized.
  • Task 3– Component Level Experimental Work
    • In this task, experimental work will be conducted on component level to verify the outcome of Task 2
  • Task 4– Large Scale Experimental Work
    • In this task, a full-scale specimen of the proposed prefabricated barrier system will be conducted to verify the outcome of tasks 2 and 3.
  • Task 5–  Assessment of the Performance of the Proposed Prefabricated Barrier System
    • In this task, full performance assessment of the proposed prefabricated barrier system will be conducted in addition, a comparison between the proposed prefabricated barrier system with the most common prefabricated barrier system.
  • Task 6 –  Final Report
    • In this Task, Full assessment of the findings from Task 1 throughout Task 5 will be conducted and a report will be published including design recommendations of the proposed prefabricated barrier system with UHPC connections.

Research Team:
Principal Investigator:  Dr. Islam M. Mantawy
Co-Principal Investigator: Dr. Atorod Azizinamini
Research Assistant:  Abbas Khodayari

 Previous Progress Reports: