Seismic performance of an innovative steel and reinforced concrete composite bridge pier

Reinforced concrete is widely used for bridge piers in Taiwan. Due to the requirements of strength and ductility for seismic design of RC bridge pier, a large number of reinforcement is usually required. This tight arrangement of reinforcement not only complicates the construction works, it also increases the risk of construction during the erection of the large number of reinforcements. In order to reduce the construction risk due to the collapse of the large reinforcement cage, an innovative steel and reinforced concrete composite bridge pier, which replaces partial vertical reinforcement of the conventional RC pier by the H-shaped sectional steel, was proposed. For the newly developed composite pier, the sectional steel can not only provide the support for the stirrup cage and hold the longitudinal bars during construction, it can also enhance the confinement effect of the inner core concrete. Consequently, not only the construction safety can be improved, seismic performance of the proposed pier is also better than a conventional RC design. In this paper, the design of a 0.6 scaled model and the construction practice of the composite bridge column are described. In addition, experimental studies for the proposed system as well as a conventional RC column were conducted and tested at the National Center for Research on Earthquake Engineering (NCREE) in Taiwan. By comparing the experimental results of the developed system with those of the conventionally detailed one, the high seismic resistance of the proposed pier in effect of ductile steel and good confinement provided by the stirrup cage and the steel section was confirmed.