Design Guidance for UHPC Connections of Precast Girders Made Continuous for Live Load

Project Information
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Use of continuous bridge spans can reduce the required section size and can improve bridge durability by reducing the number of deck joints. If not detailed and constructed properly, continuity connections for precast concrete girders using conventional concrete tend to crack from the bottom due to moments resulting from creep and shrinkage effects in the girders. Ultra-high performance concrete (UHPC) has been successfully used in multiple applications related to connection of precast concrete bridge components and is frequently used in accelerated bridge construction In general, joints replaced or connections made using UHPC will have better durability and will allow for a smaller quantity of material to be used while still obtaining adequate load transfer between connected components. Previous research has shown that connections of precast girders for live load continuity using UHPC are a promising alternative to conventional connections. However, more comprehensive design guidance for continuity connections made with UHPC is needed for a variety of precast concrete bridge configurations.

The objectives of the proposed research are to synthesize existing data and research on UHPC and UHPC connections to develop design guidance for UHPC connections of precast bridge girders made continuous for live load and to produce training materials for UHPC continuity joints.

Task 1 – Literature Review

A comprehensive literature review including U.S. and international sources will be conducted to identify previous research on precast girders made continuous for live load, UHPC material properties relevant to continuity connection design, performance of different UHPC mixtures, and other types of UHPC connections.

Task 2 – Examination of Current Design Practice

Current practice by U.S. state DOTs and in other countries relative to precast bridge girders made continuous for live load will be examined utilizing publicly available standard drawings and project information along with contacting representative state DOTs where this type of connection is used frequently.

Task 3 – Synthesis of Available Data and Current Design Practice for Design Guidance

Information identified in Tasks 1 and 2 will be used to reconcile differences between AASHTO LRFD design provisions for continuity joints, current construction practice, results from completed structural testing, and material behavior of UHPC.

Task 5 – Development of Design Examples and Training Materials

Two design examples will be prepared for two different bridge configurations that will discuss selection of the connection system used along with detailed design. Voice-over PowerPoint presentations will be created summarizing the proposed design guidance and the design examples.

Task 6 – Reports and Guide for Design of UHPC Continuity Connections

Quarterly progress reports and a final report in Microsoft Word and ADA compliant Adobe Acrobat pdf will be provided at the end of the project year. The proposed guide will summarize design guidance synthesized as part of Task 3.

Research Team:
Principal Investigator: Royce Floyd, Ph.D., P.E., S.E.
Co-Principal Investigator: Jeffery S. Volz, Ph.D., P.E., S.E.
Research Assistant: Dip Banik