Journal of Bridge Engineering

Force–deformation relationships of waterway vessels play an important role in the impact-resistant design of bridge structures. Characterizations of barge bow force–deformation (i.e., crushing) behaviors found in design provisions and previous research are reviewed as part of the present study. Results obtained from use of the relationships in impact analyses are then compared with computed responses from high-resolution finite-element barge–bridge collision simulations. As motivated by the comparisons, new relationships are proposed to further enhance designer capabilities for head-on barge impact design. In developing the proposed relationships, a parametric study of nonlinear dynamic collision simulations is performed to account for impacted pier surface geometry and barge bow versus impacted surface widths. Considerations are also made for impact velocities and peaks in force magnitudes that can occur for deformations near to the onset of nonlinear bow crushing. Merits of the proposed force–deformation relationships are then assessed via the shock spectrum approximation method. Key characteristics of barge bow force–deformation relationships (e.g., initial stiffness, maximum force, residual force plateau, impulse) are identified across typical ranges of bridge vibration periods and also in relation to propensities of empirical curve components for bringing about severities in computed structural demands.

The occurrence of disasters such as earthquakes, cyclones, tsunamis, and floods affect the resilience of bridges. In the last four decades, about 2,130 bridges were collapsed due to various disasters in India, and out of these, almost 1,105 bridges were ruined due to floods. However, in the existing practice of measuring the resilience of bridges, resilience matrices overlook the dynamism of bridge resilience and fail to address the uncertainty of variables influencing the resilience of bridges due to floods. Therefore, this study aims to develop the fuzzy system dynamics (FSD) model to simulate and forecast bridge resilience considering complex interconnections among different infrastructures and government systems. For this, the study first shortlists 14 variables related to bridge resilience using the Delphi method. Then, the cause-and-effect feedback loop and stock-and-flow diagram are formulated to explore the interdependency among these system dynamics variables of bridge resilience. Fuzzy measures and integral are used to establish the soft relationships and the existing mathematical formulas to explain the hard relationships in the FSD model. The proposed FSD model is used to simulate and forecast scenarios of the resilience of 12 bridges against floods. The structure and behavior of the FSD model are validated by conducting the dimension consistency test, structure verification test, and sensitivity analysis. The proposed model can be helpful to bridge owners to manage bridge assets, prioritize the repair and rehabilitation of bridges, propose the new bridges, devise the new policy, coordinate with other utilities and governance agencies, and thus enhance the bridge’s resilience against floods.

The measurement of reaction forces at bridge bearings would enable engineers tasked with maintaining bridges to detect potential damage to the bearing and bridge by detecting changes in the load distribution at the supports with time. Currently, measuring the load in the bearing requires sensors built into the bearing, which means that they are hard to repair when damaged and cannot be installed after the bridge is built (unless the bearings are replaced). A potential alternative is the use of distributed fiber optic sensors (DFOS) that could be used to measure curvature in the beams of a bridge, which can then be used to calculate the moment, shear, and ultimately reaction force due to live loading. To investigate this, a DFOS system was installed on a newly built steel girder bridge on a single beam near one of the piers. A series of load tests were undertaken using a truck with a known load and driving along the bridge directly over the instrumented beam at speeds ranging from pseudo-static up to 30 km/h. The maximum measured strain in the bridge beam was 15 microstrain, which was lower than can be measured with certain DFOS systems, and highlighted the need to select a system with appropriate accuracy and precision. The measured strains were used to calculate the beam shear at the pier as the truck moved across the bridge. These results were compared with a continuous beam and two grillage analyses, and it was found that, based on the continuous beam model, about 25% of the total truck load was being carried by the beam, which was lower than the code live load distribution factor suggested. The grillage models provided better estimates of load spreading but were still conservative and dependent on the choice of transverse stiffness.

Concrete-encased concrete-filled steel tube (CFST) is an innovative composite member that consists of the inner CFST components and an outer reinforcement concrete encasement. One increasing application scenario of concrete-encased CFST is acting as the arch rib in large-span arch bridges that are generally constructed through a three-stage procedure. Consequently, significant two-stage initial stresses in the steel tube and inner CFST are commonly generated, which might influence the structural behavior of the arch ribs. This paper aimed to study the effect of the high-level two-stage initial stresses on the sectional performance of concrete-encased CFST arch subject to axial compression. Accordingly, six concrete-encased CFST stub column specimens with two-stage initial stresses, as well as 12 reference specimens with preload on steel tube or CFST only, were tested and analyzed through a refined finite-element model. The simplified prediction formula for ultimate compressive strength of concrete-encased CFST stub column with different initial stress scenarios were also established. The results show that the column specimens with two-stage initial stresses generally failed due to the premature crushing of outer concrete caused by the pronounced outward swelling effect from the yielded and locally buckled inner steel tube. The yielding and local buckling of steel tube were fairly hastened by its initial stress. Therefore, it is recommended that the initial stress ratio of steel tube should be limited within a reasonable value in the design. The specific value is around 0.6 within the scope of the structural parameters of this study.

This paper proposes a novel form of gravity foundation for long-span suspension bridges. The foundation combines a caisson with bored piles and thereafter is termed a caisson-bored pile composite anchorage (CBPCA) foundation. Based on a typical suspension bridge case study with traditional caisson foundation, the feasibility of the proposed foundation was evaluated. To further capture the performance of the CBPCA foundation, three-dimensional (3D) finite-element analyses were performed. The 3D finite-element method (FEM) was validated by comparing the simulated horizontal displacements of a nine-pile group with the reported field monitoring data. Parametric studies were also conducted to investigate the effects of various parameters associated with bored piles on the CBPCA foundation performance. The numerical analysis results indicate that increasing the pile diameter can significantly reduce the horizontal displacements of the theoretical joint point (TJP) and the structural forces of bored piles. In addition, the effect of the pile arrangement was also studied. The feasibility of reducing construction time and costs by adjusting the length of some bored piles was also discussed. Moreover, the soil strength has a great influence on the stability of the CBPCA foundation, implying that it may be not suitable for soft soil conditions, namely, a soil strength ratio smaller than 0.4 in this study.

Reissner’s principle (R-P), which considers the effect of all secondary shear stresses on shear deformation, is proposed for analyzing the elastic behavior of a composite box girder with corrugated steel webs (CBG-CSWs) under restrained torsion. The cross-sectional geometrical properties were calculated considering the accordion effect of corrugated steel web (CSW), and the formulas for warping normal stress and shear stress were derived. Based on this, the governing differential equation for restrained torsion of the CBG-CSWs was established based on R-P. In comparison with the widely used Umanskii’s second theory (U-ST), the expressions of the governing differential equation are the same, but the formulas for warping coefficient introduced in the derivation are different. A numerical simulation of the trapezoidal section simply supported girder was used to verify the effectiveness of the proposed theory. Comparing the stress results with three-dimensional finite-element (FE) confirms that the R-P is more accurate and suitable for analyzing the elastic torsion of the CBG-CSWs than U-ST. The warping coefficient calculated by U-ST is larger than that calculated by R-P, but it does not mean that the results of U-ST are favorable. The CSW is mainly subjected to torsional shear stress, whereas the bottom slab bears both warping normal stress and shear stress and attention should be paid to prevent oblique cracks. The variation of web thickness, width–span ratio, and height–span ratio also affect the restrained degree of sectional torsion, sectional geometric properties and stress results, which should be considered in the reasonable design of the CBG-CSWs. The influence of secondary shear stress on the total shear stress cannot be ignored. The proposed method based on beam theory avoids the complexity of the FE model development and solution, and its results can provide a reference for the restrained torsion analysis of the CBG-CSWs.

The objective of this study is to evaluate the accuracy of prestressed girder camber calculations compared with field-measured camber from two precast plants. Field data on 189 Missouri girders with initial camber measurements and 33 girders with later camber measurements were compared with girder camber calculations using the original Missouri DOT method. The measured initial camber was on average 23% greater than the calculated camber, with an RMSE of 20.6 mm (0.81 in.) and an average error of 35%. The camber at a later point in time was only 11% greater than the calculated camber, with a RMSE of 19.6 mm (0.77 in.) and an average error of 19%. A major source of the difference in the measured and calculated camber was the measurement error introduced by sag of the measurement string line used at the precast plant. Other errors related to the estimation procedure were, in order of importance, support conditions, daily temperature gradients, temporary temperature during curing, concrete strength/age, concrete modulus, and creep parameters. All have a significant impact on camber calculations, with changes in camber from 23% to 4%. Other factors, such as prestressing force, section properties, concrete density, strand eccentricity, shrinkage, humidity, and long-term time-dependent analysis method, were systematically investigated and found to have minor impacts (less than 5% change in camber). Incorporating modifications to account for the measurement line sag, overhang length, concrete strength, and curing temperature reduced the underprediction of camber to 1.3% with a RMSE of 14.9 mm (0.59 in.) and an average error of 21%.

Accurate thermal properties are crucial for modeling the response of infrastructure to fire scenarios. While other researchers have contributed significant effort toward characterizing the thermal behavior of parallel-wire structural cable stays, no method has been derived explicitly for suspension bridge main cables, which are typically two orders of magnitude larger in cross section. These cables cannot be treated as monolithic steel sections due to the nature of their composition, and their thermal behavior is greatly influenced by voids and point contacts between their constituent cylindrical wires. This study derives the first empirically driven estimation of the effective bulk thermal conductivity of suspension bridge main cables using the data collected from thermal experimentation on a full-scale mock-up of the main cable panel (approximately 10,000 wires, 52 cm diameter, 6 m long) and gradient-based optimization of a representative finite-element model. Results show that the effective thermal conductivity of suspension bridge main cables is more than an order of magnitude smaller in the radial direction than in the axial direction and that the effective radial conductivity is an order of magnitude smaller than previous theoretical estimates have predicted. The resulting bulk conductivity serves as a useful tool for engineers and researchers because it allows a large, thermally complex geometry to be modeled as a simple monolith with orthotropic thermal conductivity properties.

An inerter-based damper termed electromagnetic inertial mass damper (EIMD) has been demonstrated as a high-performance passive damper for bridge stay cables. However, how to design an EIMD for suppressing cable multimode vibration remains largely unsolved. Here, we present practical design formulas of the EIMD for cable multimode control. A Q-point method is presented for EIMD design aiming at cable multimode control. Then, we propose asymptotic solutions of the optimal parameters of the EIMD for maximizing the damping ratio of the Q point, which guarantees that the modal damping ratios within the mode range considered are no less than that of the Q point. The accuracy of the practical design formulas is verified via both numerical study and full-scale test data. In addition, two design examples of real cables in China, including a 634-m-long cable, are presented. Comparisons of the results illustrate that the modal damping ratios offered by the EIMD outperform the counterparts of viscous dampers. This study provides practical design formulas for an EIMD or other similar dampers for cable multimode control.

A rocking column has excellent earthquake resistance and post-earthquake recovery capacity. However, concrete spalling or crushing easily occur at the rocking interface due to local high compression stress. In this paper, a rocking mechanical hinge (RMH) is proposed that can minimize the local damage, as well as being able to improve the construction rate of bridge piers. The RMH uses post-tensioned tendons to provide recentering capacity and oval steel dissipaters to dissipate energy. Simplified analytical equations are developed to analyze the hysteretic behavior of the RMH column. Based on the developed simplified analytical equations, the initial post-tensioned (PT) axial load ratio, the PT area ratio, the eccentricity of the bearing plate, and the energy dissipater ratio are parametrically studied, and the recommendation values of key parameters are identified accordingly. Furthermore, nonlinear time history analyses are conducted to investigate the seismic performance of the RMH column, compared with the conventional reinforced-concrete (RC) column and the conventional rocking column. Results show that the RMH column has superior seismic performance, with negligible residual displacement compared with the conventional RC column, and sustains minimized local damage compared with the conventional rocking column.

Abstract

The design of long-span cable-stayed bridges is governed by dead and erection loads, as well as wind loading. Despite the importance of dead and erection loads, their impact on the behavior of built structures is unknown, owing to limitations in using conventional sensors (e.g., strain gauges) during construction. To address this knowledge gap, this paper introduces three-dimensional (3D) digital image correlation (DIC) as a method to measure the erection-induced and dead load behavior of bridges. DIC is a portable, noncontact photographic technique that relies on pattern recognition and photogrammetric triangulation principles to calculate strains. This method was demonstrated by measuring the behavior of the Governor Mario M. Cuomo Bridge—a twin-span, cable-stayed bridge—between two intermediate construction stages. The strains from the anchoring of six cables and the application of the tie-down force were measured in the two edge girders, the end floor beam, and the supplemental longitudinal truss. Results indicate that the strains in the girders were similar in magnitude and approximately symmetrical in direction. Shear behavior was observed in the end floor beam between the north edge girder and the tie-down. At the location of the shop weld of the end floor beam, an increase in strain was observed from the thicker side to the thinner side, with a change from flexure toward shear dominant behavior closer to the tie-down. Measured results are compared with predictions from a 3D finite-element model, further verifying this measurement technique. While this method is demonstrated for the Governor Mario M. Cuomo Bridge, DIC can be broadly used for the measurement of dead load and erection-induced strains, providing unprecedented information on behavior. Recommendations for implementing DIC for monitoring bridges during erection are provided.

Practical Applications

This paper introduces a method to measure the behavior of long-span bridges during erection. Specifically, a photographic measurement technique, known as digital image correlation, can track the strains induced between different stages of construction. Hardware includes two cameras that are mounted on a rigid bar, a sensor controller, and a data acquisition laptop, as well as a power source (e.g., a portable generator). Photographs of bridge components, for which a pattern has been preapplied, are taken at different stages. Then a software package is used to calculate the strains based on pattern recognition. This technique overcomes the barriers of using conventional sensors (i.e., strain gauges) during erection, as the system does not need to remain onsite between erection stages and a constant power source is not required. This technique is demonstrated for the case study of the Governor Mario M. Cuomo Bridge, a twin-span cable-stayed bridge, but the technique could be used widely across the bridge industry.