Shear strength of steel fiber reinforced lightweight self-consolidating concrete joints under monotonic and cyclic loading

The shear behavior of precast concrete segmental bridges depends on the type of joints between the segments. However, there are few studies evaluating the shear strength of steel fiber reinforced lightweight self-consolidating concrete for application to precast concrete bridges. The purpose of this study is to compare the shear behavior of joints made of general concrete with developed concrete that includes lightweight aggregate and steel fiber under monotonic and cyclic loading. In this study, the push-off shear test was performed in accordance with experimental parameters of different concrete mixtures, key type, confining stress, and application of epoxy between the segments. The tests were carried out to assess the shear strength, shear behavior, crack propagation and failure mode of joints. The test results represented shear capacity of joints decreased 15.2% by replacing normal coarse aggregates with lightweight aggregates but could be enhanced through the incorporation of hooked-end steel fibers. The shear capacities of joints fabricated using developed mixture tended to be underestimated compared to analytically calculated strengths. Furthermore, the normalized stiffness of the joint was decreased with an increased number of load cycles under high-amplitude low-cycle load. The shear resistance through aggregate interlock may gradually decrease with increasing number of cycles resulting in failure at 85% of the failure load of the monotonically tested specimen. An appropriate level of confining stress and application of epoxy shall be considered to prevent sudden failure of joints at high amplitude cyclical loading conditions.