Study on Seismic Performance of Steel Fiber Reinforced Concrete Pier Under Bending–Torsion Coupling

To systematically study the mechanical behavior of a steel fiber-reinforced concrete (SFRC) pier under bending–torsion coupling, three pier specimens with a clear height of 1200 mm, a diameter of 300 mm, and an SFRC height of 300 mm in the plastic hinge region were designed and fabricated. Quasi-static tests were carried out to observe the damage patterns and failure modes of the specimens. On this basis, multiple finite element models were established using the ABAQUS 2018 software to study the influence of the torsion–bending ratio and SFRC height on the seismic performance of the pier. The results show that the bending–torsion coupling effect leads to a decrease in the bending and torsion capacities of the pier. The presence of torque causes the plastic hinge position to move up and the plastic hinge area to expand. Adding SFRC at the bottom of the pier can effectively improve the bearing capacity of the pier under earthquake action. The optimal height of SFRC is half of the clear height of the pier under the common torsion–bending ratio, which can not only improve the seismic performance of the structure but also avoid material waste.