Abstract Segmental column–supported bridges (SCSBs) are being adopted more widely in the construction industry owing to their various benefits, e.g., better quality control, shorter construction time, less environmental impact, and smaller residual displacement. With the growing applications of SCSBs, they are more likely to be constructed across active fault rupture zones. However, the behavior of SCSBs during fault rupture events is rarely understood. This paper conducts numerical studies on the seismic responses of SCSBs under across-fault ground motions induced by a strike–slip fault. The seismic responses are evaluated for both SCSBs and the reference monolithic column–supported bridges (MCSBs). Three-dimensional explicit finite-element models are established in LS-DYNA (version R7) for the two bridge configurations. The SCSB and MCSB models are validated by the previous experimental results. The calibrated segmental column model is then assembled within the full bridge framework to investigate its seismic responses. The seismic responses of SCSBs and MCSBs are evaluated by varying fault crossing location, permanent ground displacement, and fault crossing angle, and the corresponding trends are discussed. Numerical results show that SCSBs have superior performance compared to the MCSBs.
Abstract Although numerous studies have focused on vehicle impacts on bridge piers, the effects of direct collisions on stay cables in cable-stayed bridges remain relatively underexplored. To address this gap, this study investigated the dynamic responses of stay cables under vehicular impact through a combination of scaled physical tests and numerical simulations. Inclined scaled cable specimens were tested to replicate realistic collision conditions, capturing dynamic responses such as impact force evolution, cable deformation, and localized damage. The test results indicated pronounced plastic deformation and slippage near the anchorage zones, but no complete cable failure was observed. A finite-element model was developed and calibrated based on the experimental data, and then extended to simulate vehicle-to-cable impacts on a representative bridge at various collision angles. The numerical results showed that guardrails could reduce peak impact forces by up to 84.7% under small-angle impacts. However, as the collision angle increased, the redirection effectiveness of the guardrail was diminished, resulting in a higher probability of direct vehicle–cable contact and increased impact severity. The magnitude of the impact force also increased notably with larger collision angles.
This study aims to demonstrate the feasibility of using cost-effective, freely available satellite imagery to achieve reliable, long-term bridge health monitoring. A three-span Warren through truss bridge (IL-251) in Peru, Illinois, is selected as a case study, in which Multi-Temporal Interferometric Synthetic Aperture Radar (MT-InSAR) analysis is integrated with finite-element analysis (FEA) to monitor line-of-sight displacements over 9 years. A total of 223 freely available Sentinel-1A satellite images, acquired across three intervals (2015-2017, 2019-2021, and 2022-2024), are processed using permanent scatterer interferometry to extract midspan displacements. Furthermore, a detailed FEA of the bridge is conducted to predict the bridge's thermal displacements. The MT-InSAR results demonstrate strong seasonal thermal deformation trends, with displacements ranging from approximately -6 mm during summer to +4 mm during winter, confirming the structural stability of the bridge over a 9-year monitoring period. While both the MT-InSAR and FEA capture the general seasonal trend, deviations up to 6.7 mm between MT-InSAR and thermal-only FEA results are observed under certain conditions. To investigate these discrepancies, the effect of vehicular live load is considered. Additional FEA simulations incorporating estimated live loads based on traffic volume explain the remaining differences. Furthermore, classifying MT-InSAR measurements by traffic conditions improved the correlation between displacement and temperature, reaching R values up to 0.89. The findings demonstrate that freely available satellite imagery offers a scalable and low-cost method for reliable long-term bridge health monitoring under both environmental and operational loads.
The diaphragms in a T-girder bridge serve as critical structural elements for maintaining lateral stability and structural integrity of the bridge. However, the middle diaphragms are particularly susceptible to cracking under vehicular loads, which may impair lateral load transfer and ultimately compromise bridge integrity. This study proposed a transverse strengthening technique that uses prestressed steel bars (PSBs) to enhance the integral mechanical property of an existing reinforced concrete T-girder bridge exhibiting prevalent diaphragm cracks. A finite-element analysis was first conducted to investigate crack initiation mechanisms and determine optimal PSB placement and prestress magnitude. Vehicle load tests were then performed to validate the strengthening effectiveness by quantitatively evaluating the bridge's mechanical performance both before and after reinforcement. Comparison results demonstrated that the PSB transverse strengthening technique could significantly enhance the transverse stiffness of the bridge. The applied prestress not only reduced the crack widths in the diaphragms but also restrained crack propagation. Notably, the load distribution coefficient for directly loaded girders decreased by 17.2% after strengthening, indicating improved load-sharing capacity across the superstructure.
Seismic isolation has become a mature and widely adopted strategy for mitigating earthquake-induced damage in high-intensity seismic regions. The incorporation of energy dissipation (ED) devices has further advanced this approach, leading to the development of vertical-lateral resistance-decoupled (VLRD) girder-support systems for high-speed railway bridges. This functional separation confines inelastic deformations to replaceable ED components, thereby preventing plastic hinge formation in primary structural members. However, in tall piers with large cross sections, insufficient control of pier-generated inertial forces during strong ground motions can amplify seismic demands and increase the risk of pile foundation damage. To address this issue, semihinged (SH) column-footing connections have been introduced to reduce force transmission to the foundation, but their integration with VLRD systems remains unexplored. The interaction between SH substructures and VLRD superstructures may induce complex force redistributions that affect overall safety and resilience. This study investigates the seismic resilience of high-speed railway bridges equipped with a novel combination of VLRD girder-support system and SH column-footing connection. Four connection configurations were analyzed: (1) transversely fixed girder-support with fixed-base piers (TF-F), (2) friction pendulum bearings with fixed-base piers (FPB-F), (3) FPBs combined with steel restrainer bars and fixed-base piers (SRB-F), and (4) FPB-SRB VLRD with SH piers (SRB-S). Detailed finite-element models incorporating validated hyster-etic models of SRBs and SH connections were developed in OpenSees (version 3.7.0). Incremental dynamic analyses under spectrally di-verse near-fault ground motions were conducted to quantify component- and system-level fragility. Results indicate that the proposed SRB- S system markedly reduces pier curvature and bending moment demands while effectively controlling girder-support relative displacements. These findings highlight the potential of integrating SH substructures with VLRD superstructures to enhance the seismic resilience of tall hollow piers in high-intensity seismic regions.
During 2021-2024, four vehicular bridges were constructed in the United States using hybrid, fiber-reinforced polymer (FRP) composite tub (CT) girders. However, these bridges are single-span, simply supported structures, and the wider application of the CT girder will require adapting it to continuous, multispan configurations to increase design efficiency, reduce live load deflections, and improve serviceability. Indeed, two multispan, continuous CT girder bridges are currently under construction; however, their success hinges on the development of a live-load continuity joint to carry negative moments at interior piers and integral abutments. While live-load continuity joints are routinely used and well understood for precast concrete girder bridge construction, their implementation in CT girder bridges is not straightforward due to the requirement that FRP bottom-flange compressive stresses be transferred between discontinuous girder ends. This study directly addresses this challenge through the development of a novel CT girder live-load continuity joint that relies on a short length of concrete infill within adjacent discontinuous girders. The concrete is mechanically bonded to the purposely deformed girder interior via shear friction, while the girder serves as concrete formwork, easing construction. A rational design methodology is presented to determine the necessary length of concrete infill given a required moment capacity and girder cross section while also accounting for flange compressive buckling. A heavily instrumented, large-scale prototype is tested to failure to assess joint performance, and measured strains are compared with calculated values. The efficiency gains made possible by the live load continuity joint are then assessed via a realistic design scenario. The joint exhibited 11.4% more moment capacity than predicted based on the expected failure stress at the FRP-concrete shear-friction interface. The design example showed that live load continuity results in a significant reduction in girder depth and the amount of carbon fiber needed in the girder compression flange.
In this study, the compressive membrane action (CMA) in the deck slab of I-steel-concrete composite bridges was investigated. Nine static loading tests were conducted, and finite-element (FE) analyses were developed. The FE models were validated by test results and used to conduct parametric studies. The investigation examined the effects of the deck slab dimensions, transverse connection form, restraint conditions, and loading conditions. Through analysis of load-deflection curves, slab end rotation, concrete cracking, bolt strain, and slab lateral expansion, the mechanism and factors influencing the formation of CMA in the deck slab were explored. The results demonstrate that the deconstructable bolted connectors effectively transferred the interfacial shear force, and the CMA effect enhanced the ultimate load capacity by 33%-256% compared to the theoretical bending capacity. The most significant improvement was observed in deck slabs characterized by lower reinforcement ratios, larger thickness, weaker rotational restraint, and two-point loading. Specifically, the increase attributed to the CMA effect in slabs with weak rotational restraint was 4.4-6.4 times higher than that in slabs with strong rotational restraint. To estimate the load capacity of deck slabs considering the CMA effect, formulas for the lateral and rotational restraint stiffness are proposed based on the test and FE analysis results. The comparison of test results demonstrates the effectiveness of the proposed formulas.
The collapse of the Francis Scott Key (FSK) Bridge in Baltimore on March 26, 2024, presents an opportunity to evaluate US design guidance for addressing low-probability, high-consequence events involving essential bridge infrastructure. This paper reviews the development of vessel collision provisions, focusing on the progression of AASHTO guidelines from 1991 to the current 2009 edition, and compares them with international standards from Europe, China, Japan, Australia, and Canada. The underlying design philosophy for vessel collision is critically compared with established blast and seismic design approaches to assess adequacy and identify gaps. A representative case study is used to frame a critique of the current AASHTO provisions for critical bridges, and a framework is proposed to advance existing standards toward consequence-based, deterministic mandates for physical protection, leveraging modern data analysis and simulation tools.
Steel girder ends in bridges can be susceptible to corrosion damage from deicing salts, water, and other contaminants that leak from failed deck expansion joints. When corrosion becomes significant, it can decrease the sectional properties of steel girder ends and eventually reduce structural resistance against bearing and shear. Conventional methods that are typically used to repair corrosion-damaged girders require a substantial amount of time and resources to complete and often cause public inconvenience due to traffic lane closures. Thus, there is a critical need for practical, rapid, and cost-efficient repair solutions suitable for implementation by local DOT maintenance teams. The main concept of the proposed Sandwich Panel repair method is to encase the corroded region in a filler material, such as cementitious grout or an alternative, and reinforce it with threaded rods. To expedite installation and eliminate the need for formwork removal, two bent thin steel plates installed on both girder sides serve as stay-in-place formwork. Therefore, this repair method eliminates the labor-intensive steps of jacking, welding, and formwork disassembly, making it more cost-effective and less time-consuming. The structural performance of the Sandwich Panel repair method was validated through five large-scale experimental tests, considering parameters such as (1) threaded rod layout, (2) filler material, and (3) support conditions. This study primarily focused on the repair of steel girders without full-depth stiffeners, whose bearing strength is more sensitive to web deterioration. The repair successfully restored, and even exceeded, the design web crippling capacity of the W24 & times; 68 steel girder, calculated in accordance with AASHTO LRFD methodology. A complementary parametric study was conducted using finite-element models that were benchmarked against experimental results and validated the efficacy of the repair.
In-service girder-end restraint devices in long-span suspension bridges inevitably degrade, which directly alters their mechanical parameters and affects bridge service safety. It is imperative to quantitatively identify girder-end restraint parameters for their performance evaluation. Because current methods typically require laboratory testing after disassembly, this study proposes a novel, hybrid method, driven by monitoring data and numerical modeling, for the in situ online calibration of girder-end restraint parameters in suspension bridges. First, an inversion method for girder-end restraint forces (GERFs) was derived by establishing an explicit mapping relationship between GERFs and vehicle-induced girder-end displacement (VIGED) differences. Second, a physics-informed theoretical reconstruction model of the VIGED under longitudinal unconstrained conditions (LUC-VIGED) was established to estimate VIGED differences. On this basis, a statistical equivalence-based correction method was introduced to refine the reconstructed LUC-VIGED for operational bridges. Third, a decoupling and quantitative identification algorithm for the mechanical parameters of multirestraint devices was proposed. Finally, the proposed method was validated through numerical simulations and a case study on an in-service suspension bridge. It accurately identified girder-end restraint parameters, including damper damping coefficient and expansion joint stiffness, and showed good agreement with short-term field test results. These findings provide valuable insights for the performance evaluation of restraint devices in suspension bridges.
Socket connection is a commonly used connection method in accelerated bridge construction (ABC). The socket depth directly affects the connection reliability, force transmission mechanism, and foundation expenditure, especially changing the strength, elastic stiffness, and ductility. Determining a reasonable minimum socket depth is therefore a key design issue. This study investigates this problem through an integrated approach combining experimental, numerical, and theoretical analyses. First, quasi-static cyclic tests on three large-scale column-foundation socket specimens with varying socket depths were conducted to evaluate their failure modes, hysteretic behavior, and key performance parameters. Subsequently, a high-fidelity finite-element model was developed and validated against the experimental results. A comprehensive parametric study using this model quantified the influence of the longitudinal reinforcement ratio (rho s) and socket depth on the normalized strength and ductility. Based on these findings, simplified empirical equations were proposed to predict the minimum socket depth as a function of rho s for satisfying strength and ductility criteria, respectively. Furthermore, theoretical analytical models for determining the minimum socket depth based on flexural strength equilibrium and initial elastic stiffness equivalence were established and verified. Finally, a practical design framework synthesizing these equations and models is presented for engineers. An important conclusion is that, for constant material strengths, the required minimum socket depth is predominantly governed by the column's reinforcement ratio. This paper provides a rational and comprehensive framework for determining the minimum socket depth of socket joints in ABC.
Damaged RC structures are typically strengthened in the load-carrying state in practice, which limits the improvement of their mechanical performance due to stress lag in the strengthening components. In this study, the shear performance of damaged thin-walled web RC beams strengthened with an ultrahigh-performance concrete (UHPC) layer and postinstalled adhesive bolts under secondary loading was experimentally and numerically investigated. Direct shear tests were first conducted to study the interfacial shear behavior between UHPC and normal concrete with different interface treatments. Subsequently, the three-point bending tests were performed to assess the performance evolution of the strengthened beams under secondary loading, i.e., strengthening under sustained loading conditions. The results demonstrated that even under secondary loading, the UHPC layer could still effectively constrain crack propagation and improve the shear performance of the damaged RC beams. However, due to the strain lag of UHPC induced by secondary loading, the UHPC strength was not fully utilized, leading to 15.7% and 10.8% reductions in the stirrup yielding load and ultimate load, respectively, compared with the strengthened beam without secondary loading. Finite-element analysis further indicated that the detrimental effect of secondary loading intensified with increasing sustained load levels but was mitigated as the UHPC layer thickness and postinstalled bolt ratio increased. Based on the experimental and numerical results, a combined surface treatment of mechanical chiseling followed by high-pressure water jetting at 80 MPa is recommended for effective UHPC-based shear strengthening of thin-walled web RC beams.
Because of their geometry, materials, and the nature of the applied loads, pedestrian bridges are subject to dynamic effects that can compromise user comfort and safety. Therefore, this study conducts a design space exploration of composite footbridges with tubular profiles and a warren truss pattern. Accordingly, a framework composed of Rhinoceros (version 8), Grasshopper (version 6), and Karamba3D (version 3.1) software was developed to evaluate both the static and dynamic behavior of the footbridge, taking into account the structure's natural frequencies. Geometric parameters (span, height, width, and modular spacing) and topological configurations were assessed, including variations in deck type (composite steel deck or precast concrete panel), presence of concrete top slab, lateral bracing, and lateral restrictions at the ends of the top chords, evaluating their influence on vertical and lateral vibration modes of the footbridge. A sampling methodology similar to Latin Hypercube was adopted, in which each combination of different parameters represents an instance. The analyses showed that the vertical vibration mode was more critical in relation to the adopted normative limit, with frequencies below 5.0 Hz for spans starting at 30 m, whereas in the lateral mode, all natural frequencies were above 2.5 Hz. Height-to-width ratios >1 increased the natural frequency of the vertical mode without significantly affecting the lateral mode, and are therefore recommended, especially for longer spans. The topological configuration featuring a deck of precast concrete panel, without a top slab and with lateral bracing, stood out for its superior performance regarding natural frequencies. The element that exhibited the greatest influence on the vertical vibration mode's natural frequency was the top chord, while in the lateral mode of the free model, the struts, verticals, and bottom chords became more influential as the span increased. In the model with lateral restriction at the top, the bottom and top chords had greater influence.
Extreme pitting depths in bridge cable steel wires serve as fatigue crack initiation sites, making accurate assessment crucial for failure risk prediction. Existing methods require rust removal and cable disassembly, which not only disrupts traffic but also permanently damages serviceable cables, resulting in resource waste. A method is proposed for predicting extreme pitting depth distributions from in situ images of steel wires without rust removal. A multisource collaborative representation approach integrating color, texture, edge, and deep learning features captures corrosion information associated with pitting statistical patterns. Multiple instance learning aggregates local image features into vectors reflecting macroscopic characteristics, resolving inconsistency between local observations and statistical patterns. An interpretable model predicts the location parameter mu, scale parameter sigma, and 99th percentile Q99 of the extreme pitting depth distribution. Field validation on in-service bridge cables shows relative errors of 15.31%, 3.56%, and 5.80%, respectively. The predicted distribution parameters can be converted to strength loss estimates and mapped to National Cooperative Highway Research Program (NCHRP) Report 534 corrosion stages, enabling integration with established cable assessment frameworks. This approach demonstrates a practical pathway for in situ corrosion assessment.
