Evaluate the performance of closure joints for side-by-side accelerated bridge construction (ABC) superstructure systems by using field instrumentation methods

Date
2022-07-13
Authors
Shah, Niyam A.
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Abstract

The main problem facing engineers and contractors today is devising a plan to fix deteriorating bridges while also accommodating vehicles on the roadway and keeping workers safe. One way to do this is through the use of accelerated bridge construction (ABC), which accomplishes the goal of minimizing traffic disruptions and construction time by utilizing prefabricated elements and systems. In order to provide continuity between these prefabricated elements, a connection known as a closure joint must be used. Closure joints are critical in ABC and help transfer shear and moment between prefabricated deck panels. However, there has been concern regarding the long-term durability of closure joints due to their cast-in-place nature. This thesis provides an overview into the instrumentation program carried out at two bridges in Texas – the Navasota River Bridge in the TxDOT Bryan District and the Farwell Creek Bridge in the TxDOT Amarillo District. The instrumentation of these TxDOT bridges was intended to provide the researchers an indication of how close the strain values of the closure joints were to design assumptions. The Navasota River Bridge used RSFRC as its closure joint material, while the Farwell Creek Bridge utilized a proprietary UHPC mix known as SmartUP®. The Navasota River Bridge, which has 20 strain gauges installed, was monitored for approximately one year while the Farwell Creek Bridge, which has 26 total gauges installed, was monitored for approximately seven months, with the data summarized herein. Monitoring of these bridges will continue beyond this thesis submittal, and all data collected under this project will be included in the final project report to TxDOT. The primary objective of the instrumentation program was to capture the strain in both the longitudinal and transverse direction within the closure joint connections and convert them into the structural behavior parameter of engineering strain. Through the use of equations previously derived at the University of Texas at Austin, the researchers were able to process the data to provide a meaningful and coherent interpretation. The instrumentation confirmed that concrete volume shrinkage was present throughout the monitoring period. Specifically, autogenous shrinkage was dominant for the first three or four days followed by drying shrinkage becoming dominant after seven days. Ultimately, the researchers found the recorded field strain data was not significant to the point of concern for structural behavior.

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