Different software platforms may influence the surrogate model’s comparison and evaluation results. To overcome this challenge, this paper develops a unified surrogate modeling framework to predict the structural responses of a steel box girder bridge under moving-load analysis, ensuring consistency in both data generation and model assessment. Numerical simulations are conducted in MIDAS Civil to generate datasets of bridge’s deflection and combined stresses under variations in uniformly distributed and concentrated loads, as well as their simultaneous changes. Based on identical datasets, deep neural network, polynomial chaos expansion, and Gaussian process, are constructed and implemented within COMSOL for a consistent comparison. The models’ performance is quantified using the mean absolute error, root mean square error, and coefficient of determination. Bridge structural responses under moving-load analysis are effectively captured by all three surrogate models. The Gaussian process model performs best for single-parameter variations, while the polynomial chaos expansion model is more robust for multi-parameter cases. Stress responses are more sensitive to prediction errors than deflection. The proposed framework serves as a valuable benchmark for surrogate modeling-based prediction of bridge structural responses.
Many cast-in-place reinforced concrete box culverts in Louisiana were built using outdated standard plans originated from the 1940s and updated in the 1970s. These culverts often yield low load rating factors when evaluated using current AASHTO procedures. Despite this, they performed satisfactorily overtime with minimal signs of distress. Simple 2D frame element models are commonly used for structural analysis of typical box culverts due to their ease and speed. However, they tend to produce more conservative load rating results compared to complex modeling techniques like 3D plate element models. A parametric study was conducted using 120 3D finite element culvert models in various configurations, along with corresponding 2D frame element models. Correction factors were developed to correlate moment values from 3D and 2D analyses. Field testing of representative culverts was also performed to validate the analytical models. The study considered two types of wall-slab connections: pinned and moment connections. The results indicate that using moment connections, an at-rest lateral earth pressure coefficient, k o of 0.50, and the 3D-2D correction factor, yields more realistic load rating values that reflect field conditions. The study’s findings were used to develop guidelines for load rating reinforced concrete box culverts in Louisiana, which can also be applied to similar culverts elsewhere.
The utilization of intermediate diaphragms (IDs) in precast concrete (PC) I-girder bridges has been a topic of debate among researchers for decades, with its effectiveness remaining a subject of controversy. Nevertheless, the consideration of IDs is an essential aspect of engineering practice, making it crucial to explore their role in live load moment distribution. This study delves into the application of concrete IDs, examining the impact of various finite element modeling practices and key parameters on their effectiveness. A sensitivity study was conducted to compare the efficacy of grillage, planar, and solid models in determining the suitable modeling approach for straight, skewed, and curved deck bridges equipped with IDs. To optimize modeling practices, a further investigation was undertaken to evaluate the influence of different parameters on the role of IDs, including the presence of IDs, the rigidity of connections between IDs and girders, and several geometric parameters related to the bridge span layout. The live load moment envelope of girders was chosen as the response indicator to evaluate the role of IDs. The findings of the parametric study revealed that the removal of IDs leads to an increase in the midspan moment of the interior girders, while the midspan moment of the exterior girders decreases. Furthermore, it was found that the rigidity of connections between IDs and girders, girder spacing, and span length significantly influence the role of IDs in PC I-girder bridges.
The study examines bending moment, shear force, torsional moment, and vertical deflection in skew-curved bridges. These values are compared with those of straight bridges. SAP2000v20, a finite element method (FEM) based software, is utilised for modelling and analysing the bridges, conforming to the Indian Road Congress (IRC) 6:2017 Codal provisions. The purpose of this research is to examine the behaviour of skew-curved bridges using parametric variations. Also, the equation for a skew-curved bridge with different parameters is derived. The combined impact of curvature and skewness must be considered for accurate analysis, as separate evaluations are insufficient. Additionally, the impact of high skewness in curved bridges is not well-documented, and no specific guidelines or limitations are available. Therefore, a detailed parametric study is conducted to address these gaps, providing insights into the combined influence of skewness and curvature on bridge behaviour. This study extends by considering all IRC loadings and highlights the critical findings under the specified 70R track load conditions. Variables include skew angles, curve angles, span lengths, and the number of cells. Results indicate that incorporating skewness improves the performance of bridges with greater curvature by reducing forces and deflections. Notably, double-cell curved bridges with high skewness outperform single-cell counterparts with the same curvature and the same volume of material. The equations are found to be very close to the finite element results.
Horizontally curved steel I-girder bridges are commonly designed and constructed as economical options in congested areas despite their complex behavior. Girder responses during erection and deck placement are challenging to evaluate due to warping of the girder and cross-frame system, which induces fit-up concerns and causes locked-in forces. Determination of girder major-axis bending under live load is complicated by curvature, which often makes the standard line girder analysis that uses live load distribution factors invalid; quantification of lateral responses for horizontally curved steel I-girder bridges also generally relies on refined analysis. Additionally, global temperature variations and local thermal gradients on these bridges result in more complicated radial and lateral movements and stress distribution compared to straight bridges. Standard design and analysis simplifications generally do not apply to horizontally curved steel I-girder bridges-guidelines can be complicated to follow, which could discourage usage. Some (but limited) state transportation agencies in the U.S. have distinct requirements, preferences, and procedures for design and construction of these bridges that could benefit from a nationwide synthesis. This paper holistically reviews existing experimental and numerical research on the behavior of horizontally curved steel I-girder bridges in the past two decades and synthesizes current U.S. state practices for their design and analysis, which leads to observations and insights of research and application gaps. Aspects of this review include (1) research on horizontally curved steel I-girder bridge behavior from 2000 to 2024, considering construction (during erection and deck placement) and in-service (including vehicle and thermal) loading conditions, (2) the common refined methods of analysis adopted in practice and research, (3) the U.S. state preferences and guidelines for design and analysis, and (4) the research gaps (between existing work and practical needs) and disparities in various state specifications, as well as their implications.
With the rapid advancement of the social economy and the rapid increase in the number of transportation vehicles, bridge health monitoring has become increasingly important. Using information technology to analyze data and identify damage to bridge structures can effectively ensure bridge safety, thereby avoiding traffic accidents. The current data analysis and damage identification methods have limitations, including poor real-time performance and low accuracy. An improved support vector machine algorithm is developed, in this study, for real-time monitoring data classification. Moreover, a bridge structure damage identification model is proposed based on improved support vector machine and data preprocessing. When compared and analyzed alongside other algorithms, it was found that the accuracy and precision of the improved support vector machine algorithm were 97.4% and 95.7% respectively, outperforming the other algorithms. Subsequently, a performance comparison analysis was conducted between the proposed recognition model and other models. Results denoted that the mean running time of the model was 38.1 s, outperforming the comparison models. The results demonstrated that the improved support vector machine algorithm and recognition model proposed in the study are effective and can help improve the analysis efficiency of bridge monitoring data and the accuracy of identifying bridge structural damage, providing a theoretical basis for bridge structural damage identification.
The increasing use of Fiber-Reinforced Polymer (FRP) composites in bridge infrastructure presents both opportunities and challenges for structural inspection and asset management. Although FRP systems offer superior corrosion resistance and high strength-to-weight ratios, their distinct material behavior and deterioration mechanisms are not adequately addressed in existing bridge inspection standards. This study presents a comprehensive framework for the field inspection and condition assessment of in-service FRP-reinforced and FRP-strengthened concrete bridge elements, developed in a research project funded by the Federal Highway Administration (FHWA). The framework integrates findings from experimental evaluation, nondestructive testing (NDT), and literature synthesis to produce a standardized methodology compatible with the Specifications for the National Bridge Inventory (SNBI) and the AASHTO Manual for Bridge Element Inspection (MBEI). It introduces FRP-specific element identifiers, defect typologies, and condition-rating scales consistent with national bridge data structures, enabling quantitative evaluation and uniform reporting across transportation agencies. The framework represents a foundational step toward incorporating composite materials into the federally mandated bridge management systems established under 23 CFR 650.317, facilitating data-driven maintenance, lifecycle analysis, and policy development.
This research focuses on analyzing the resonance behavior of a cracked multi-bay frame structure under the influence of moving oscillatory loads, specifically examining vibrations in both axial and vertical directions. To model the system, the finite element approach, integrated with Lagrange's formulation, was applied, utilizing the Bernoulli-Euler beam assumptions to derive the in-plane motion equations. The dynamic structural response was calculated using the Newmark integration algorithm. For damaged elements, stiffness characteristics were formulated based on principles from fracture mechanics. A three-dimensional graph showing the interdependence of crack position, oscillator speed, and peak displacement was developed to visualize the effect of crack location. The findings revealed that the initial resonant frequency corresponds to the first vibrational mode, which is predominantly horizontal, while the second resonant condition aligns with vertical mode dominance.
The effects of vertical ground motions (VGMs) on bridges have been studied mainly for completed structures. In contrast, the response of bridges during staged construction under the vertical earthquake component has not been investigated systematically. In this work, the seismic response of a two-span balanced-cantilever box girder bridge under VGMs in service and during three construction stages (50%, 75%, and 100% of the cantilever progress of each span) is studied. This bridge type is of interest because its mass and stiffness evolve during construction, reaching their highest values upon completion. The response of a 150-m-long bridge was analyzed using a computational model developed in the software Midas Civil. Multimodal response spectrum analyses were performed to determine internal forces in the girder and pier. The analyses were first conducted using horizontal (H) response spectra acceleration as defined in the Colombian bridge design Code and then including the vertical (V) component. The latter was defined based on V/H spectral relationships for far-field and near-field earthquakes available in the literature. The results show that the VGMs significantly increase the girder bending moment and the axial force in the pier during construction and service, with the largest variations occurring when the cantilever progress is 50%. This suggests that the VGM should be considered in the design of stage-construction bridges.
Indirect bridge health monitoring is a promising measurement technique which has several advantages over the conventional direct method. However, the indirect method still encounters some challenges such as the effect of road roughness and vehicle's own frequency. Utilizing the scanning vehicle in a stationary state has been proposed to overcome the effects of road roughness. Also, the contact-point response (CPR) has been developed to eliminate the vehicle's own frequency. However, CPR has been developed for undamped vehicle. Therefore, the first part of this study develops CPR calculation method for a damped vehicle model. The CPR is calculated for a damped stationary vehicle (considering various vehicle frequencies) using the proposed equations. The transmissibility of the CPR is tested by comparing the time and frequency domains between the indirect (vehicle) and bridge direct response (reference). The transmissibility of the vehicle significantly improved by computing CPR, especially for low vehicle frequencies. In the second part of the paper, a frequency-free vehicle is developed in a laboratory set-up. The response of the vehicle does not contain the frequency of the vehicle due to using polyurethane (PU) wheels. Dynamic responses, damping ratios, and mode shapes are compared between the direct and indirect method. Accordingly, the results show that the designed vehicle has high transmissibility of the bridge vibration.
This study investigates the seismic performance of self-consolidating concrete (SCC) and self-consolidating fiber-reinforced concrete (SCFRC) in full-scale beam-column joints subjected to cyclic loading. The experimental program involved applying reverse cyclic loads to evaluate critical structural parameters, including crack initiation, propagation, load-bearing capacity, energy dissipation, and ductility. The results revealed that while both specimens exhibited similar initial cracking patterns, the SCFRC specimen significantly outperformed the SCC specimen in terms of energy dissipation (35% higher at larger drift levels), maximum drift capacity (6% vs 4%), and crack resistance (first crack at 0.35% drift for SCFRC compared to 0.25% for SCC). The SCFRC specimen also required 55.6% of its ultimate load to achieve a drift ratio of 1%, compared to 59.5% for the SCC specimen, reflecting its enhanced deformation efficiency. Additionally, the SCFRC specimen maintained higher residual strength and delayed failure due to the effective distribution of stresses by the steel fibers. In contrast, the SCC specimen showed brittle behavior, characterized by rapid strength degradation and extensive cracking. Evaluation against the ACI-T1.1 acceptance criteria demonstrated that the SCFRC specimen exceeded the seismic performance requirements, offering greater resilience and ductility in comparison to the SCC specimen. These findings highlight the potential of SCFRC as a superior alternative to SCC in seismic design, reducing the need for extensive transverse reinforcement while enhancing the overall energy dissipation capacity of beam-column joints.
Analysis of large segmentally constructed cantilever bridges is a complex task. It runs through all subsystems in the construction history, keeping track of time, dead weight, prestressing, traveling formwork, temporary columns, jacking of cantilevers, etc., and then finally through the service life of the bridge. This complexity makes results very hard to judge by hand, especially the time dependent behavior, and thus, the designer becomes to a very large extent dependent on the computer program. In this paper, results obtained by various software are compared for two large segmentally constructed bridges. The comparisons revealed unacceptably large differences in long-term girder displacements and column forces. The computer program DARC, that generally gave the largest time dependent effects, was however unable to track the magnitude of measured deflections beyond 15 years for a third bridge, but agreed well with rebar strain recordings over a limited period of 2.5 years in the columns of one of the others. This investigation raises three interrelated issues: (1) improved benchmark testing of this kind of software; (2) calibration of code models for creep and shrinkage to outdoor environment and loading conditions; and (3) need for instrumentation and monitoring of segmentally constructed bridges.
Press-Brake-Formed Tub Girders (PBFTGs) provide an innovative and efficient solution for short-span steel bridges. Recognized as a 2021 Focus Technology by the American Association of State Highway and Transportation Officials (AASHTO) Innovation Initiative, these galvanized, shallow trapezoidal boxes are fabricated from cold-bent structural steel plates. This study aims to quantify the potential impact of improved live load distribution factors (LLDFs) on the applicability of PBFTGs. Using three-dimensional finite element analysis, the live load distribution behavior of a matrix of 720 Valmont U-BEAM (TM) bridges, a commercially available PBFTG solution, was analyzed with varying parameters. Statistical analysis was employed to assess the effectiveness, prediction power, and accuracy of the improved LLDFs. The impact of the improved LLDF predictions was then examined by performing a design feasibility and applicability assessment. The findings of this study contribute to the optimization of PBFTG design and the expansion of their use in short-span steel bridge construction.
Conventional bridges supported on bearing are the most widely used technique to design and construct bridges in the 21 st century. The modern standard codes have standard guidelines to build such type of structure. However, integral bridges are the latest trend in bridge engineering, to overcome several failures of the conventional system. In integral bridges the deck is monolithically connected to the piers (substructure) and thus, eliminates the use of bearings. This type of connection increases the redundancy of the structure and thus is recognized as critical for seismic design of bridges. However, for a full integral bridge along with abutments, the backfill interaction is a concern and has many uncertainties as detailed guidelines are not made available in any of the bridge design codes. In view of this, the study investigates the seismic performance of semi-integral bridge in which only the intermediate piers are monolithic with the deck and the abutment ends are free to move on the bearings provided on the abutment cap. To illustrate the benefits of bridge pier with integral connections, a comparative study is made between existing conventional bridge and the proposed semi-integral system in terms of demands and displacements. The study includes non-linear time-history analysis to evaluate the performance of conventional pier and the integral pier under seismic loads.
Highway bridge specifications do not account for the presence of railings or parapets in the analysis and design of concrete slab bridges. This paper presents a parametric investigation of the influence of railing or parapet stiffness on the wheel load distribution and bending moments in simply supported, two-equal-span, one- to four-lane concrete slab bridges using the finite-element analysis (FEA). A total of 224 bridge cases were modeled and bridge parameters such as span length and slab width were varied within practical ranges. Various railing stiffnesses were investigated by assuming that the railings were built integrally with the bridge deck and placed on both edges of the bridge. The FEA wheel load distribution and longitudinal bending moments, edge beam moments, as well as live-load deflections were compared to reference bridges without railings, and to the AASHTO design procedures. The FEA results showed that the presence of railings reduced the maximum negative bending moment in slab bridges by a range of 15%–70%, and the positive moment by a range of 10%–60%. This reduction in bending moments due to the presence of railings can be considered an increase in the load-carrying capacity of concrete slab bridges by a significant amount, especially in the cases of lesser number of lanes. The results of this parametric investigation will assist bridge engineers in either designing or evaluating concrete slab bridges by using refined FEA analysis to quantify the contribution of railings in resisting highway loading. This approach of using FEA modeling may serve as an effective alternative for strengthening existing concrete slab bridges.
Integral abutment bridges (IABs) exhibit complex and evolving structural behavior due to their interaction with the foundation and surrounding soil. Long-term effects, such as backfill soil ratcheting and cumulative in-plan superstructure rotation, can lead to unexpected structural responses that are not fully understood. This study analyzes more than 3 years of superstructure displacement, abutment rotation (tilt), and temperature data, collected at 0.5 Hz, from an in-service two-span skewed (45°) steel I-girder bridge with integral abutments and staggered-X-cross-frames. The study advances the understanding of IAB behavior, including behavioral anomalies, which could assist in the interpretation of stress deviations reported in previous studies. Findings show that the monitored IAB presents changing behavior, as well as an accumulation of transverse displacement and abutment tilt over time. Analysis indicates that boundary condition representation in finite element models should incorporate the flexibility provided by soil and pile deformation to accurately reflect field behavior. It is further observed that abutment tilt data displays different trends over short and long periods. Discrepancies between these trends underscore the complexity of IAB behavior under varying temperature conditions. Deep learning techniques, particularly long short-term memory models, assisted in identifying these behavioral patterns. This application demonstrates their potential for detecting subtle deviations in bridge response.
The use of precast concrete (PC) is gaining attention in the bridge industry due to its inherent advantages, such as reduced traffic disruption, the safety of both workers and the traveling public, and construction efficiency. As the connection location of precast bridge piers often coincides with the plastic hinge regions, using precast piers in high seismic zones is challenging. Furthermore, seismic design specifications impose strict requirements for transverse reinforcement in these regions for better energy dissipation. Combined with the typically high longitudinal reinforcement ratio in bridge piers, high transverse reinforcement requirement leads to steel congestion in the plastic hinge regions, which significantly affects the construction quality. The use of active confinement (transverse prestressing) at the plastic hinge region can potentially help with the steel congestion issue. However, the application of active confinement using conventional materials has proven to be problematic. Shape memory alloys (SMAs) with their unique thermal prestressing capability offer an effective technique for applying active confinement. This study presents a new solution for steel congestion in PC bridge piers using SMA spirals. The proposed design significantly reduces steel congestion by reducing transverse reinforcement in the concrete core of plastic hinge regions without increasing the member size and stiffness, as well as seismic demand. The performance of the proposed SMA-confined pier is investigated numerically through a parametric study. The results prove the feasibility of the proposed concept for use in high seismic regions.
