Theoretical Calculation and the Design Method of Tall Dual-Column Bents With Shear Beams Validated by Simulations and Tests

Dual-column bents with energy dissipation components represent one structural type of seismic resilient bridge bents. However, there have been few dynamic analyses and shaking table tests to validate the theoretical formulas, design methodology, and the seismic effects of the energy dissipation elements on dual-column bents, particularly for the tall dual-column bents. Thus, the study aims to derive theoretical formulas for calculating the yield strength, yield displacement, and elastic stiffness of tall dual-column bents with and without shear beams (SBs). This enables a more comprehensive understanding of structural performance and allows for more accurate predictions of the seismic behavior of these novel bents during seismic events compared to existing studies. A structural fuse-based design methodology for tall dual-column bents was developed and validated through verified finite element models and shaking table tests. Both numerical and experimental analyses were conducted to evaluate the effectiveness of SBs in mitigating seismic damage and responses in tall dual-column bents. The displacements and curvatures of the tall dual-column bents with and without SBs were analyzed. The results show that SBs enhance the seismic resilience and decrease the seismic responses of tall dual-column bents by strategically yielding first to dissipate energy, achieving up to 69.5% displacement reduction under E1-level earthquakes (PGA = 0.40 g) and 77.6% curvature reduction under E2-level earthquakes (PGA = 0.68 g) compared to tall dual-column bents without SBs. Crucially, this prioritized yielding mechanism enables SBs to function as structural fuses, suppressing structural responses below critical yield thresholds and safeguarding columns. Consequently, the tall dual-column bent without SBs undergoes seismic damage under E1-level earthquakes, while the tall dual-column bent with SBs does not suffer any damage. SBs enable the tall dual-column bent to meet performance targets. This suggests that SBs notably enhance the seismic resilience of tall dual-column bents, and the proposed design method can be used to design actual engineering structures.