Abstract Summary
Eliminating expansion joints in bridge decks is considered a good alternative to address deck joint issues, reduce maintenance, and improve bridge-deck life expectancy. Using a link-slab to make the bridge girders (partially continuous) continuous only for lateral and longitudinal load effects, provides lower cost, improved durability, longer spans, improved seismic performance, better resistance to wind loads and storm wave loads, improved structural integrity, and improved riding quality. The aim of this research paper is to monitor and investigate the performance of the link-slab of a pedestrian bridge that is reinforced with Basalt fiber reinforced bars (BFRP). The research also investigates the concrete simple-span beams that are made continuous by pouring the continuity link-slab between the beam ends. The research provided recommendations for the instrumentation of the link-slab, a suggested monitoring plan, and an instrumentation system to monitor the temperature, strain, and elongation of link-slabs. The bridge has been instrumented with embedded and surface-mounted sensors and has been monitored to evaluate the performance of the new link-slab during concrete casting and after casting. Several types of sensors were used, and a data acquisition system recorded strains/deformations at regular time intervals. The preferred sensor types for this application are vibrating wire sensors with integrated thermistors. The sensors were strategically located on both sides of the midline of the link slab to capture strains in the BFRP bars, strains in the concrete link-slab, and the gap between adjacent beams’ ends. The research team started measuring and monitoring the strains, deformations, and cracks in the link-slab. The team also investigated the performance of the link-slab, evaluated the data from installed instrumentation, analyzed the results, and provided conclusions. All measurements have been corrected for temperature changes. Data has been collected during service over two periods of approximately 3 months each. The data captured was related to the temperature and shrinkage of the concrete and did not include any significant live loading since no load testing was performed. The strains experienced by the sensors indicated small strain levels compared to the BFRP ultimate strain levels. In addition, to live load flexural effects, thermal cycling could contribute to the concrete cracking over time in the link-slab if tension stresses build up due to global shrinkage and creep restraint of the connected FSB spans. After about 90 days over the time of monitoring, the average strain in the mid-joint gauges did not change significantly indicating minimal creep and or shrinkage restraint was experienced to date by the link-slab since the initial casting date. The maximum daily strain change due to thermal effects is about 500 microstrains.
