Shake table tests of economical precast ultra-high performance concrete bridge piers with different fiber types and seismic joint materials

Ultra-high performance concrete (UHPC) is a rapidly growing solution for complex superstructures, particularly in regions susceptible to high seismic activity. However, implementing UHPC at the full structural components scale is still challenging because of the associated costs and slow development of design guidelines. Few studies in the research community focus on structural seismic applications, and none incorporate sustainable materials like recycled steel fibers, which can significantly lower the UHPC cost. Thus, this study fills a significant knowledge gap and focuses on the dynamic seismic performance of large-scale precast UHPC bridge piers that exclusively use economically scalable UHPC mixtures with recycled steel fibers. With a focus on bridge piers with accelerated bridge construction (ABC) grouted duct connections, three large-scale precast UHPC bridge piers were fabricated at an actual precast facility in California and tested on a shake table under dynamic earthquake excitations. The UHPC bridge piers varied based on the type of UHPC fibers (manufactured versus recycled steel fibers) and the grouting material in the ABC joint (conventional grout versus UHPC). The paper presents new data and knowledge on seismic response and plastic hinge behavior of UHPC from dynamic shake table tests and successfully demonstrates the viability of scalable UHPC with recycled steel fibers for seismic bridges.