Document Type

Thesis - Open Access

Award Date

2017

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

First Advisor

Mostafa Tazarv

Second Advisor

Nadim Wehbe

Keywords

bridges, longitudinal joint, precast concrete, rehabilitation

Abstract

Prefabricated bridge elements have become an essential part of accelerated bridge construction (ABC), which is an emerging technology to expedite bridge construction. Among several bridge girder types, precast double-tee girders are common on county bridges in South Dakota because of the ease of construction, the reduced construction time, and the potentially lower overall cost. However, the longitudinal joints of these bridges are rapidly deteriorating with many needing replacement before the expected 75- year service life. Research was conducted at South Dakota State University (SDSU) to develop, construct, and evaluate the performance of rehabilitation methods on this type of bridge. Current detailing between adjacent double-tee bridge girders consists of discrete welded steel connections. Wehbe et al. (2016) showed that this longitudinal joint detailing is insufficient for fatigue, service, and strength loading, thereby significantly reducing the lifespan of these type of bridges. Currently, there are more than 700 doubletee girder bridges in South Dakota incorporating this joint detailing. Twenty joint detailing alternatives for the rehabilitation of the longitudinal joint of double-tee girder bridges were proposed in the present study. Of the 20 alternatives, continuous joint details were selected for further study since they offer minimal durability issues. Ultra-high performance concrete (UHPC) and latex modified concrete (LMC) were selected as the filler materials because of their improved strength and durability. Thirteen large-scale beam tests were carried out to investigate the performance of the selected joint rehabilitation details and to select the best for large-scale testing. Subsequently, two joint concepts, “pocket” and “continuous”, were developed and analytically investigated using linear finite element analyses to optimize the selected joint detailing. A full-scale 40-ft long double-tee bridge consisting of two interior girders was constructed using conventional longitudinal joint detailing then initially tested under fatigue loads. Subsequently, the bridge was rehabilitated using the two proposed details, “pocket” joint with UHPC and “continuous” joint with LMC each incorporated on half the length of the bridge. The rehabilitated specimen was first tested under 500,000 cycles of the AASHTO Fatigue II loading followed by an additional 100,000 of the AASHTO Fatigue I load cycles. Stiffness tests were performed to monitor the degradation of the bridge. Finally, the specimen was monotonically tested to failure. No significant damage beyond initial shrinkage cracks in LMC was observed throughout the fatigue testing. In addition, the stiffness of the bridge did not degrade. No damage or yielding of the reinforcement in the joint was observed throughout the strength testing. The rehabilitated bridge met all the AASHTO limit state requirements indicating sufficient performance. Overall, both rehabilitation methods are structurally viable alternatives for rehabilitation of double-tee bridge girders to extend their life for another 75 years. However, only UHPC should be used as filler material. The rehabilitation cost of a double-tee bridge with pocket detailing will be only 30% of the bridge replacement cost.

Description

Includes bibliographical references (pages 182-186)

Format

application/pdf

Number of Pages

232

Publisher

South Dakota State University

Rights

Copyright © 2017 Lucas Michael Bohn

Share

COinS