Title: Simplified transverse post-tensioning construction and maintenance of adjacent box girders
Date: Spring, 2012
Volume: 57
Issue: 2
Page number: 64-79
Author(s): Jenna Hansen, Kromel Hanna, Maher K. Tadros
https://doi.org/10.15554/pcij.03012012.64.79
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Abstract
Precast, prestressed concrete adjacent box girders are regularly considered for short- to medium-span bridges on secondary roads. This corresponds to spans from 20 ft to 127 ft (6.1 m to 38.7 m), though typically no
more than 40 ft (12.2 m). Many of these projects have limited funding or require rapid construction. Secondary roads are also subject to a certain amount of public criticism, particularly with regard to cost and aesthetic appeal. Research has shown that an appealing structure can be defined as having continuously flat soffits and high span-to-depth ratios—characteristics of an adjacent box system. Proper design and detailing of the transverse connection between girders is essential to minimizing both initial cost and long-term maintenance. Typical connections include diaphragms and cast-in-place concrete toppings, which directly increase both cost and time of construction. Inadequate post-tensioning is the primary cause of reflective cracking leading to ingress of chlorides and the consequent reinforcement deterioration, excessive girder deflection, and possible unexpected failures.
This paper presents the results of testing on a post-tensioned transverse system that eliminates the need for diaphragms and a concrete overlay. Post-tensioning was determined based on previous research on a similar system that was not post-tensioned. Results indicate that the system does not exhibit strain change or cracking under fatigue loading and would be an excellent candidate for practical applications.
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