Mechanism of Using L-Shaped Steel Plate and Rubber to Enhance Seismic Performance of Bridge Pier with Low Reinforcement Ratio

A railway pier with a relatively low reinforcement ratio has a high risk of collapse when subjected to an earthquake. The use of a conventional strengthening method of concrete, steel, and fiber-reinforced polymer jackets cannot effectively enhance the deformation capacity of the railway bridge pier, given the relocation of the failure position. This study proposed a novel strengthening device that consisted of L-shaped steel, rubber, stainless steel screws, and high-strength studs and investigated its effect when enhancing the cyclic behavior of a railway pier with a low reinforcement ratio of 0.2%. The experimental results showed that the proposed strengthening device enhanced the initial stiffness, loading capacity, and dissipated energy of the bridge pier without reducing the deformation capacity compared with the unstrengthened pier. The strengthening device and reinforcement were independent components to sustain loading at the failure stage. The contributions of the strengthening device and reinforcement to the total dissipated energy were 40% and 60%, respectively. Their contributions to the loading capacity were 18% and 50%, respectively, and the axial loading provided another 32% contribution. A theoretical formula that considers the contribution of each component to the loading capacity at the failure stage was established, which accurately predicts the mechanical behavior of the pier.