Abstract
Closure joints are commonly used in bridge deck to connect two adjacent prefabricated elements in accelerated bridge construction. The current practice of closure joints utilizes the use of different materials such as normal strength concrete and ultra-high performance concrete with the use of different reinforcement details such as straight bars, hooked bars, and headed bars. The design of closure joint to meet strength limit state is quite simple, however, the design for service life for these joints is quite challenging. Framework for service life design of closure joints in bridges, built using accelerated bridge construction techniques, is developed in this paper. This framework includes several steps: 1) identification of project requirements especially those influences the service life of closure joints; 2) identification and selection of feasible closure joint types suitable for the project requirements; 3) identification of factors which influence the service life of closure joints along with mode of failures and consequences; 4) identification of suitable approaches or strategies for mitigating failure modes or assessing the risk of damage; 5) modification of closure joint detail using mitigation strategies which may result in the development of several alternatives and options for each closure joint type; 6) estimation and comparison of service life for each modified alternative using finite or target service life approach; and 7) conducting life-cycle cost analysis for each modified alternative along with the selection of the optimum closure joint details to meet both strength and service life demand. This framework is used in practical design implementation example for 1400-ft long bridge in Boston, Massachusetts, US. Several closure joints details were studied under this research such as the use of normal strength concrete with straight bars, 180-degree hooked bars, 90-degree hooked bars, and headed bars along with the use of ultra-high performance concrete with straight bars. This paper summarizes the outcome of the design for service life of those closure joints comparatively.
Highlights
Accelerated bridge construction (ABC) is a construction technique that uses innovative design, materials, and construction methods to reduce construction time for both new construction and rehabilitation (Culmo et al, 2011)
The option of overlay made on normal-strength concrete (NSC) and bottom deck sealer presents the most economical initial cost for closure joint and mitigation strategies, it results in high life cycle cost due to the increased number of repair intervals
This manuscript adopts the general framework presented in a Pre-Print at http://onlinepubs.trb.org/onlinepubs/shrp2/ SHRP2prepubR19AGuide.pdf
Summary
Accelerated bridge construction (ABC) is a construction technique that uses innovative design, materials, and construction methods to reduce construction time for both new construction and rehabilitation (Culmo et al, 2011). Very narrow closure joints demand development of reinforcement in short distances and potentially use of UHPC that has a high cost of water in the field, resulting in higher water/cement ratios and overvibration that can cause aggregate segregation. Framework for service life design of closure joints is provided in a flowchart format as shown in Figures 4, 5 This framework adopts the general procedure of American Society for Testing Materials International (2017); they are specific for bridge deck closure joints. Straight bars, headed bars, 180◦ hooked bars, and 90◦ hooked bars are commercially used in bridge deck closure joint These reinforcement details are selected to develop feasible alternatives since each reinforcement detail controls the design width of FIGURE 7 | Superstructure cross-section. The joint width for this alternative is 3 ft. according to LRFD Guide Specifications for Accelerated Bridge Construction (2018)
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