Although fiber-reinforced composites have the potential to enhance the seismic performance of bridge columns, their use has been hampered by their poor workability and inadequate compaction for cast-in-place applications. To address this issue, this study developed a self-compacting hybrid fiber reinforced concrete (SC- HyFRC) composite. Optimized specifically for bridge columns, this composite flows under its own weight, completely filling the formwork and achieving full compaction without internal or external vibration. In addition, this SC-HyFRC provides enhanced ductility, shear resistance, and damage
tolerance compared to conventional fiber-reinforced composites.
To investigate the seismic performance and post-earthquake damage resistance of bridge columns composed of SC-HyFRC , two 1:4.5 scale column specimens were built and tested statically under uni-directional cyclic loading. In both specimens the volumetric transverse reinforcement was 0.37%, which is two to three times less than that of typical Caltrans bridge columns. Both test specimens had the same longitudinal steel ratio of 1.2%.
The design of the two specimens differed in terms of the location where the nonlinear deformations were accommodated. The first specimen was designed to rock at the column’s base–foundation interface. Incorporating stainless steel bars as longitudinal reinforcement, the second specimen was designed to form a flexural plastic hinge at its base. Both specimens attained large drift ratios of up to 11% without losing axial load carrying capacity and were successful in resisting damage due to spalling of concrete up to drift ratios of 3.6%. Compared to a conventional reinforced concrete column of same dimensions,
longitudinal steel ratio, and axial load ratio, the SC-HyFRC columns exhibited superior damage resistance and better load carrying capacity despite a 50% reduction in transverse reinforcement.
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