The seismic fragility of reinforced concrete (RC) bridge piers is critical for urban rail transport systems, as severe pier damage may interrupt post-earthquake operation and threaten network safety. Compared with conventional highway bridge piers, urban rail transport RC solid piers usually have lower axial load ratios, larger cross-sections, and stricter serviceability requirements. However, the combined effects of geometric parameters, reinforcement detailing, and material strength on their cyclic behavior, dynamic response, and seismic fragility remain insufficiently understood. To address this issue, seven 1/4-scale RC solid pier specimens were tested under quasi-static cyclic loading to examine the effects of pier height, transverse reinforcement ratio, and longitudinal reinforcement ratio on damage evolution, hysteretic response, skeleton curves, and energy dissipation. A fiber-based OpenSees model considering bond-slip effects was then established, validated against the tests, and extended to a full-scale prototype pier for parametric analysis. The effects of aspect ratio, axial load ratio, longitudinal reinforcement ratio, stirrup ratio, steel yield strength, and concrete strength were evaluated under cyclic loading and nonlinear dynamic time-history excitations. An incremental dynamic analysis-based probabilistic seismic demand model was further developed using 30 near-fault ground motions, with peak ground acceleration as the intensity measure and displacement ductility as the engineering demand parameter. The results showed that increasing the aspect ratio changed the failure mode from flexure-shear-dominated to flexure-dominated behavior, increasing the ultimate displacement from 122 mm to 155 mm while reducing the peak lateral strength from 263 kN to 248 kN. Increasing the longitudinal reinforcement ratio improved both peak strength and ultimate displacement, from 226 kN to 262 kN and from 120 mm to 160 mm, respectively. The numerical results indicated that aspect ratio, axial load ratio, and longitudinal reinforcement ratio had more pronounced effects on seismic demand and fragility than stirrup ratio. Increasing steel yield strength generally reduced seismic fragility, whereas increasing concrete strength enhanced lateral resistance but did not necessarily improve fragility performance. These findings suggest that the seismic performance of urban rail transport RC solid piers should be evaluated by combining cyclic response, dynamic demand, and fragility-based performance, rather than by maximizing any single design parameter.

Double-column reinforced-concrete (RC) hollow bridge piers are often assessed using flexure-dominated models, although their thin walls can develop shear-related deterioration. This study reanalyzes seven previously reported cyclic tests on scaled square hollow-pier columns and extends the assessment to a full-scale double-column system in OpenSees. The tests varied the shear-span ratio and transverse and longitudinal reinforcement. A flexure-only fiber model and an axial–flexure–shear interaction membrane–beam–truss element model (AFSI-MBTEM) were evaluated using six response indicators before cyclic and nonlinear time-history analyses of the prototype system. Lower shear-span ratios increased resistance but intensified inclined cracking, stiffness loss, and post-peak deterioration; increasing L/D from 3.9 to 7.9 reduced peak strength from 320.5 to 145.9 kN. AFSI-MBTEM reduced the mean absolute errors in peak strength, yield displacement, and effective stiffness to 3.08%, 11.83%, and 12.86%, respectively, but did not improve residual-displacement or mean hysteretic-loop-energy predictions. At the system level, shear-span ratio most strongly affected cyclic stiffness and peak base shear; wall-thickness ratio, width-to-depth ratio, and longitudinal reinforcement were also influential. Under three near-fault records, AFSI-MBTEM predicted 5.31–10.32% lower peak base shear, while displacement changes remained record-dependent. Shear-sensitive modeling improves force and deformation assessment, but the system-level trends remain conditional on the adopted prototype, parameter ranges, and records.

Rectangular reinforced concrete (RC) hollow bridge piers may exhibit significant shear participation after flexural cracking and yielding, whereas their seismic responses are commonly evaluated using flexure-dominated numerical models. This study investigates the effects of axial–flexure–shear interactions on the cyclic response and seismic fragility of rectangular RC hollow bridge piers. Cyclic loading tests on seven one-eighth-scale specimens were analyzed to characterize the effects of the shear-span ratio and reinforcement configuration. The experimental results were then used to assess a conventional flexure model and an axial–flexure–shear interaction model, denoted as AFSI–MBTEM. Full-scale piers with heights of 16, 24, and 32 m were subsequently analyzed under cyclic loading and representative near-fault ground motions. Finally, 7200 nonlinear time-history analyses were conducted using 80 records divided into non-pulse and short-, medium-, and long-period pulse-like groups, while seismic fragility curves were developed using displacement ductility as the demand parameter. The tests indicated flexure-dominated but distinctly shear-sensitive behavior, particularly for specimens with low shear-span ratios. Compared with the flexure model, AFSI–MBTEM reproduced pinching, post-peak deterioration, and hysteretic energy more accurately, reducing the mean absolute error in hysteretic energy from 23.57% to 13.29%. For the full-scale piers, model differences generally decreased as the pier height and shear-span ratio increased together, although the effects on large-deformation stability and seismic response remained configuration- and ground-motion-dependent. AFSI–MBTEM predicted higher fragility in 46 of the 48 height–motion–damage-state comparisons. At the upper analyzed intensity of PGA = 1.5 g, it also produced higher DS4 exceedance probabilities in the examined critical cases. Within the investigated section configurations, axial-load ratios, and coupled height–shear-span cases, the results indicate that neglecting axial–flexure–shear interactions may lead to nonconservative fragility estimates, particularly for configurations with greater shear participation.

To enhance the understanding of the seismic behavior of reinforced concrete (RC) hollow piers, a sensitivity analysis of design parameters is conducted. A novel analytical model named the Axial–Flexure–Shear-Interaction-Membrane-Beam-Truss-Element-Model (AFSI-MBTEM) is proposed to account for the flexure–shear coupling. To avoid size effects, three full-scale rectangular RC hollow piers are simulated and validated using the AFSI-MBTEM. Based on a benchmark model, the influence of parameters on seismic responses is explored under cyclic loading, earthquakes, and different PGAs. The AFSI-MBTEM can efficiently and accurately capture the symmetric and asymmetric hysteretic curves of RC hollow piers. The influence of parameters under cyclic loading is generally consistent with that under strong earthquakes. The aspect ratio, width-to-depth ratio, wall thickness ratio, axial load ratio, and longitudinal rebar ratio have a significant influence under cyclic loading, earthquakes, and different PGAs. The influence of stirrup ratio, concrete strength, and longitudinal rebar strength becomes clear under earthquakes, especially for residual deformation. The suggested parameter values for hollow piers are as follows: aspect ratio of 4–6, width-to-depth ratio of 1.0–2.0, wall thickness ratio of 20–40%, axial load ratio of 0.05–0.10, longitudinal rebar ratio of 1.2–2.2%, stirrup ratio of 0.8–1.2%, concrete strength of C40, and longitudinal rebar strength of 400 MPa and 500 MPa.

Rapid post-earthquake assessment of urban rail viaducts requires nonlinear pier models that capture cyclic deterioration at manageable computational costs. This study calibrates and evaluates the established Ibarra–Medina–Krawinkler (IMK) formulation for reinforced-concrete solid piers rather than proposing a new hysteretic law or experimental database. Seven previously reported quarter-scale tests are reused for direction-specific parameter identification and calibration-set assessment. The new contribution is a multilevel accuracy–efficiency evaluation covering cyclic metrics, a scaled 12 m Fiber benchmark, nonlinear dynamics, incremental dynamic analysis (IDA), computational cost, and fragility. For the specimens, final secant stiffness achieved R² = 0.891 and a 9.93% mean absolute percentage error; cumulative energy achieved R² = 0.893 but a 27.79% error. For the prototype, the intermediate-backbone force difference was 3.83%. Under eight representative records, mean differences were 2.64% for peak base shear and 4.15% for peak displacement. Across 60 records scaled from PGA = 0.1 to 1.5 g, peak–displacement and peak–base–shear comparisons yielded R² values of 0.854 and 0.931. The corresponding mean absolute percentage errors were 15.95% and 11.32%. The IMK model reduced wall-clock time by 96.37%, a 27.55-fold speed-up. Paired fragility curves differed by 3.14 percentage points on average, and median PGA capacities differed by 11.23%; Sa(T1) and capacity-dispersion checks preserved the main comparison. Because the record groups were not matched in spectral amplitude or velocity, their ranking is interpreted as an association rather than a causal pulse-period effect. The calibrated IMK model is therefore suitable for rapid global demand and fragility assessment within its calibration domain, whereas Fiber models remain preferable for local damage, residual deformation, and detailed energy dissipation.

The longitudinal seismic response of a high-pier long-span stiff-skeleton arch bridge is spatially asymmetric because unequal pier heights, the fixed–movable bearing arrangement, and arch–pier interaction create nonuniform force transfer paths, even when the installed fluid viscous dampers (FVDs) obey a symmetric velocity-dependent law. This study evaluates that response redistribution and the mitigation achieved by longitudinal FVDs under near-fault motions. A three-dimensional SAP2000 model was established using elastic beam elements for the girder, arch ribs, cap beams, and piers, Plastic (Wen) links for spherical steel damping bearings, foundation springs for pile–soil interaction, and Maxwell-type FVD links. Thirty combinations of damping coefficient and velocity exponent were first screened under an El Centro record scaled to 0.64 g. The selected case (α = 0.3 and C = 2000 kN·${\left(s/m\right)}^{\alpha }$) was then evaluated by paired analyses of models with and without FVDs under 15 records grouped descriptively as short-, medium-, and long-period pulse-like motions and non-pulse motions. Across the paired record set, the mean record-wise reductions were 21.34% for bridge-wide maximum bearing displacement, 27.56% for P2 pier-top displacement, 9.73% for bridge-wide maximum pier-base shear force, and 12.62% for bridge-wide maximum pier-base bending moment. Mean arch rib reductions ranged from 10.00% for axial force to 25.00% for bending moment. Seven of the eight monitored response metrics decreased under all 15 records; arch rib axial force decreased under 14 records and was unchanged under 1. Local force increases nevertheless occurred at several arch-supported piers in the spatial El Centro comparison, demonstrating that global mitigation does not imply spatially symmetric or uniformly beneficial component response. Within the selected record set, the medium-period group produced the largest average demands for several response measures, but this is a sample-specific observation rather than a resonance inference. Removing the extracted velocity pulse component reduced most responses, although the nonlinear original-versus-residual comparison cannot be interpreted as an additive pulse contribution. The paired record set check supports the robustness of the selected FVD case for the investigated sample, but does not establish record-independent optimality.