Study on the impact of vehicle-induced vibration on the flexural behavior of UHPC joints in widened bridges

Abstract Bridge widening involves phased construction of adjacent structures to maintain uninterrupted traffic flow. This process exposes freshly placed longitudinal joints between staged deck constructions to vehicle-induced vibrations, potentially compromising their mechanical integrity. This study investigates the flexural behavior of ultra-high-performance concrete (UHPC) longitudinal joints under such vibrations through model tests. To simulate actual site conditions, we developed a novel vibration test setup that replicates the dynamic environment experienced by these joints during construction. Micro- and meso-scale tests were conducted to examine the flexural behavior of longitudinal joints following vibration exposure. Results revealed that vibration amplitude significantly influences fiber orientation and flexural strength of ultra-high-performance concrete (UHPC) wet joint specimens. Low-amplitude vibrations (3 Hz at 1 mm and 3 mm) enhanced fiber orientation, increasing flexural strength by 11.5% to 19.8% and ultimate load capacity by 17% compared to non-vibrated specimens. Conversely, high-amplitude vibrations (3 Hz at 5 mm) adversely affected fiber orientation, decreasing flexural strength by 23.9% and ultimate load capacity by 19% relative to non-vibrated specimens.