Experimental Study on the Seismic Performance of Reinforced Concrete Bridge Piers with Welded Reinforcement Cages

Welded reinforcement cages (WRCs), which connect longitudinal reinforcement and stirrups through welding, have attracted increasing attention for industrialized construction of reinforced concrete (RC) structures. However, the welding process may introduce heat-affected zones, residual stresses, and local metallurgical changes in reinforcing bars, raising concerns regarding the potential influence of welded longitudinal-bar-to-stirrup connections on the seismic performance of RC bridge piers. This study experimentally investigates this issue through quasi-static cyclic tests on two large-scale RC bridge pier specimens with identical reinforcement layouts but different reinforcement connection methods. One specimen adopted conventional tied connections between longitudinal reinforcement and stirrups, whereas the other employed welded connections. The seismic responses of the specimens were evaluated in terms of failure mode, hysteretic behavior, skeleton curve, strength, ductility, stiffness degradation, energy dissipation, residual displacement, and strain development. The results showed that both specimens exhibited flexure-dominated failure with similar crack propagation and concrete-cover spalling characteristics. The differences in yield and peak strengths were within 5%, and the cumulative energy dissipation differed by only 2.1%, indicating comparable global seismic performance. The welded specimen exhibited a slightly larger ultimate displacement (12.8%) and ductility coefficient (9.4%), while the stiffness degradation characteristics remained nearly identical. Although several weld spots detached during the post-peak loading stage, no fracture or necking of the longitudinal reinforcement was observed, suggesting that the adopted welding procedure did not adversely affect the cyclic deformation behavior of the reinforcement. Within the scope of the tested specimens, the results demonstrate that welded longitudinal-bar-to-stirrup connections can maintain the seismic performance of RC bridge piers and provide experimental evidence for the potential application of WRCs in industrialized bridge construction. Further studies involving additional specimens and broader design parameters are required to validate the general applicability of these findings.