Journal of Bridge Engineering

This paper critically reviews the understanding of fire hazards in bridges. It starts with identifying dangerous fire scenarios based on previous accidents. Existing studies on the fire performance of bridges are then discussed according to different experimental and fire modeling approaches, with a specific emphasis on the structural configuration of bridges and adopted failure criteria. Next, fire resilience enhancement methods for bridges are analyzed and classified as risk-based mitigation approaches, postfire decision strategies, and fire prevention and protection measures. Finally, this paper highlights recent progress and proposes critical knowledge gaps and future research directions based on these findings.

This study investigates the working mechanism and seismic behavior of the Combined Viscous-Steel Damping System (CVSDS) considering the longitudinal wave-passage effect. In the CVSDS, the operational status of the fluid viscous damper (FVD) and the steel damper (SD) can be switched by the fuse–lock device (FLD), which is triggered by the output force of the FVD. The configuration and working mechanism of CVSDS are introduced in detail. A test model is manufactured and examined by cyclic tests to verify its fusing–locking function during cyclic motions. The numerical model of CVSDS is proposed based on the experimental result. The fusing–locking behavior and seismic reduction effectiveness of CVSDS installed in a long-span bridge is analyzed, in which the wave-passage effect is considered. The results show that the fuse–lock function under dynamic loading can be achieved by the proposed FLD. The occurrence condition of the locking mechanism activation depends on the viscous damping force. The traveling wave will induce a delay of the locking time, cause large locking intervals between CVSDSs installed at different positions, and lead to a larger required moving capacity of the CVSDSs. The mitigation effectiveness of CVSDS is significantly reduced due to the wave-passage effect.

A new lap splice connection by ultra-high performance concrete (UHPC) was proposed to connect precast bridge columns with footings or cap beams. Quasi-static tests were conducted on two large-scale precast double-column bent specimens with different aspect ratios to investigate their cyclic behavior. The test results revealed that the specimen with a larger aspect ratio (i.e., slender specimen) failed by core concrete crushing above the lower column–footing connection segments without bond failure. However, the specimen with a smaller aspect ratio (i.e., squat specimen) experienced a shear–flexure failure in the lower column–footing connection segments. In addition, refined finite-element (FE) models that incorporated the effects of bond–slip and shear–flexure interactions were developed to investigate cyclic behavior in the tested specimens further. The numerical results indicated that neglecting the effects of bond–slip and shear–flexure interactions led to overestimating the cumulative dissipated energy of the specimens. The deformation in the slender specimen was dominated by flexure and bond–slip in the UHPC, and the squat specimen was dominated by shear. Finally, the strength and deformation capacities of both specimens were evaluated. The proposed UHPC connection ensured an ultimate drift of >3% for the slender specimen and a shear strength that was comparable to a monolithic cast-in-place (CIP) bent for the squat specimen.

A parametric study using finite-element (FE) analysis was conducted over a range of sectional depths to investigate the effect of the pier caps’ sectional depth on structural safety and serviceability for pier caps with a simple determinate strut-and-tie models (STMs) design. The influence of sectional depth on the shear strength of the pier caps was also analyzed using pier caps with over-reinforced flexural rebar inducing shear failures. Analytical studies using determinate STMs showed that the amount of vertical shear reinforcement did not change regardless of the sectional depth of the pier cap. In contrast, the FE analysis suggested that excessive sectional depth could lead to overly conservative shear designs. In addition, the FE analysis showed that crack serviceability could be efficiently satisfied by constraining the pier caps’ minimal sectional depth. Based on the FE analysis, design guidelines for simple determinate STMs were proposed to determine efficient sectional depths in pier cap design.

Current evaluation of bumps at bridge approaches is limited in scope and performance, and varies in practice at different state DOTs. This study intends to propose a general criterion specifically for bridge approach bump classification and develop a formula for dynamic load allowance (IM) estimation for bridges in Oklahoma. A total of 98 bridges in Oklahoma were studied using recently developed sub-mm 3D laser imaging technology that simultaneously collected inertial profiles, sub-mm 2D/3D images, and right-of-way images at highway speeds for roughness and distress analysis. A three-level criterion that evaluates maximum roughness within an approach or departure slab is established to classify approach bumps into Good, Fair, and Poor conditions. The threshold defined in the criterion considers both the field crew’s sensation during data collection and the surface distresses that cause or are associated with different levels of International Roughness Index magnitudes. The development of the formula for bridge IM estimation is based on the established criteria while incorporating the influences of bumps from approach slab and bridge deck. The results of evaluating approach bump and IM of 98 bridges demonstrate the ability of using sub-mm 3D laser imaging technology to evaluate bridge approach bumps and bridge IM in an efficient and effective manner.

The identification of cable forces plays an important role in the construction, vibration control, and health monitoring of cable structures. In practice, cable vibrations are mainly affected by the coupling of bending stiffness, sag, inclination, and boundary conditions, so it is difficult to establish an explicit functional relationship between frequency and cable force through the vibration method for facilitating application to engineering. To overcome this difficulty, the explicit expression of the frequency of the cable considering bending stiffness, sag, and inclination is derived for the first time and a novel cable force identification method for determining the piecewise-fitted formula (PFF) according to the cable parameters is proposed. The paper first reviews the cable force identification formulas based on cable frequencies. Then, the theoretical analysis model and differential equation of cable vibration considering the aforementioned factors are established. Based on these derivations, the explicit general formula of cable force identification based on fundamental frequency is derived. Next, according to the cable parameters, the value ranges of two nondimensional parameters characterizing the bending stiffness and sag of cables are divided to fit the corresponding coefficients of the PFF. Finally, numerical simulation and experimental data show that the PFF is more accurate and applicable than the existing formulas. This method can be conveniently applied to the field detection and online monitoring of cable forces.

Uneven distribution of mass, stiffness, and strength over the length of a bridge can produce rigid body rotation of the superstructure, or “twisting,” during an earthquake. Twisting response modes lead to the concentration or amplification of damage in the bridge substructure and, as such, are undesirable. AASHTO recommends a balanced stiffness approach to limiting bridge irregularities and provides possible modification techniques for bridges that do not satisfy the recommendations. However, there is a lack of research documenting the implementation details and benefits of these modification techniques on the performance of irregular bridges. This study investigated the effectiveness of three techniques to reduce the twisting response modes for geometrically irregular bridges during earthquakes: adjusting the effective heights of the bridge columns, modifying column end fixity conditions, and redistributing the superstructure mass profile. First, analytical equations were derived to estimate the values of parameters needed to achieve a balanced stiffness using each technique for any arbitrary bridge. Next, a finite-element model of an irregular, reinforced concrete, quarter-scale bridge previously tested on a shake table was validated against available experimental data. This model was used in conjunction with a metaheuristic optimization algorithm to determine the optimal values of the parameters such that the superstructure rotation was minimized for the experimental ground motions. Then, a parametric study was performed using a suite of hazard-consistent and spectrally matched ground motions to investigate the sensitivity of the optimization results to the number and spectral characteristics of the ground motions. The parametric study showed that reducing the effective heights of the columns by stiffening the lower portion of the columns was the most effective method to reduce the twisting response of the bridge and that three ground motions with different spectral shapes were the most computationally efficient subset when performing the optimization methodology.

Rib-to-deck welded joints of in-service orthotropic steel decks (OSDs) are prone to fatigue cracks, which usually lead to considerable repair costs and traffic interruption. To mitigate or avoid fatigue cracking, an easy-to-implement strengthening method of bonding reinforcing plates on deck surfaces was developed and investigated. The fatigue tests were carried out on four full-scale specimens. The first specimen was unreinforced and the other specimens were strengthened by using single-layer carbon fiber reinforced polymer (CFRP) plates (4 mm), double-layer CFRP plates, and 4 mm-thick steel plates, respectively. The strengthening time and thickness of the reinforcing plate were numerically investigated. The test results shows that the proposed strengthening method can significantly reduce the hot spot stress of the welded joints and prolong their fatigue lives. The steel plates are more effective than the same thick single-layer CFRP plates. The double-layer CFRP plates can further increase the fatigue life of the welded joint, if the bonding quality could be greatly improved to avoid or delay debonding. The test results also support that the FAT100 hot spot stress S–N curve is suitable to fatigue life evaluation for this type of joint before and after strengthening. The numerical investigation reveals that the implementation of the proposed strengthening method should be carried out at the early stage of fatigue crack propagation, namely the early phase of the service period, to obtain better strengthening effects. This study recommends that thicker steel plates should be used for fatigue strengthening without affecting the working performance of the bridge deck pavement. This study provided a reference to the design and application of bonding reinforcing plate on deck surface in fatigue strengthening of OSDs.

This study presents a comprehensive investigation on the characteristics of the aerodynamic damping and amplitude-dependent flutter derivatives of a streamlined box girder for various wind angles of attack through a scaled section-model free vibration wind tunnel test. The response characteristics of the section model in vertical, torsional, and vertical–torsional coupled directions are investigated. A piecewise sliding windows fitting method, which is effective, generic, and at the same time provides an accurate estimation of the amplitude-dependent damping ratio, is proposed. The method is applied in three experimental measured examples, and the yielded results match satisfactorily with the measurements, confirming the feasibility and the advantage of the proposed method. Besides, the modal damping ratios of the section model for the considered degrees of freedom at different cases are identified from the method. The evolution of the aerodynamic damping with the wind speed and wind angle of attack and its influence on the generation of stable and unstable limit cycle oscillations and flutter response are discussed. The contribution of vertical and torsional motion to the generation of different flutter types is revealed. The full set of amplitude-dependent flutter derivatives is identified from the experimental modal properties of the different dynamic systems. The accuracy of the flutter derivatives is cross-validated through a free vibration wind tunnel test.

Aiming at obtaining an efficient and accurate multiscale model of suspension bridges, this paper innovatively proposed a multiscale modeling and updating framework based on measured modal frequencies and influence lines. In the first step, a multiscale model was created using the substructure method and the multipoint constraint method. The second step was to use the Gaussian process metamodel to perform multiscale model updating. For a suspension bridge with a flat steel box girder, a global model was created primarily using beam and truss elements, and the flat steel box girder of the critical section was finely modeled using shell elements. However, the refined model of the girder has many degrees of freedom. To reduce the computations, the substructure method was used to condense the refined model into a superelement. According to the multipoint constraint method based on deformation compatibility, the superelement and global model were coupled together to create a multiscale model. In terms of model updating, the theory of objective function construction based on the modal frequencies and influence lines was introduced first. Then, the trained Gaussian process model could replace the multiscale model to fit the relationship between the updated parameters and the objective function. Finally, the optimization algorithm was used to obtain the minimum value of the objective function. A case study of a suspension bridge was considered to demonstrate the effectiveness of the proposed framework. The measured deflection and strain influence lines of the bridge were obtained via a bridge moving vehicle test, and the modal frequencies of the bridge were obtained using environmental excitation. Using the proposed framework, the updated frequencies and influence lines were closer to the measured frequencies, and the computational efficiency was improved. Therefore, the proposed method could efficiently and accurately build a multiscale model of a suspension bridge.

Sensitivity analysis has become an important tool to quantify simulated structural response variability that arises from uncertain model properties and modeling assumptions. Sensitivity with respect to column, superstructure, and abutment modeling parameters was computed for two ordinary standard reinforced concrete bridges considering nonlinear static and dynamic analysis in SAP2000 and OpenSees. The sensitivity computations used finite differences for all model responses as well as a new hybrid approach that uses direct differentiation of the element and structural response and local finite differences for the material response. In addition to model properties, dynamic response sensitivity was obtained by changing the hysteretic unloading/reloading rule for the steel and concrete constitutive models used in the columns. The sensitivity analyses indicate that even though the nominal static and dynamic responses can be matched between two software packages, the responses remain highly sensitive to the hysteretic model assumptions and to variations in material properties.

Currently, the composite bridge deck (CBD) system with ultrahigh-toughness cementitious composite (UHTCC) is understood to possess improved ductility and to resist cracking. To provide recommendations for designing this structural system in engineering practice, the flexural behavior in the transversal direction of steel–UHTCC CBDs was investigated using experimental and numerical analyses. Two steel–UHTCC CBDs with plate and U-ribs, respectively, were designed to obtain experimental data, including the failure mode, load-deflection curves, slippage development, and strain distribution. Then, finite-element (FE) models were established using ABAQUS software and validated against the test results. Eleven FE examples were designed for detailed parametric analysis of the stress on the steel plate in the steel–UHTCC CBD, with the design parameters mainly including the spacing between adjacent longitudinal ribs, the thickness of the UHTCC slab, and different working conditions and rib types. The experimental and simulated results illustrated the significant effect of using the UHTCC layer on improving the toughness and durability of the CBD structure, with the local effect greatly influenced by the longitudinal rib spacings. Finally, the transition condition between global and local failure modes of the steel–UHTCC CBDs, considering different longitudinal rib spacings, was studied, and a design scheme for obtaining the transition point is proposed to provide design suggestions.

Owing to the remarkable advantages, such as the appealing appearance, light self-weight, efficient application of prestressing, and the optimal shear force and bending moment distributions in the webs, prestressed concrete composite box girders with corrugated steel webs (CBGCSWs) are widely utilized in highway bridges nowadays. To further improve the cracking resistance of traditional prestressed concrete CBGCSWs in the tensile zone and negative bending region and to promote the application of ultrahigh-performance concrete (UHPC) in long-span highway bridges, this paper proposed and designed a novel nonprismatic prestressed UHPC composite box girder with corrugated steel webs (CSWs) (i.e., CSW-UHPC composite box girder). A large-scale (5.55 m long) nonprismatic prestressed CSW-UHPC composite box girder was experimentally and numerically studied to investigate its cracking behavior and flexural performance through the bending test and finite-element analyses. Experimental results of the deflections, strains, cracks development and crack patterns, cracking moments, and ultimate flexural capacity of the girder were acquired. In addition, the calculation methods of the first cracking moment, nominal cracking moment, and the ultimate flexural capacity of the girder were comprehensively investigated, and the analytical results agreed relatively well with the experimental ones. The proposed novel nonprismatic prestressed CSW-UHPC composite box girder exhibited excellent cracking performance and flexural capacity. Results obtained from the present study could serve as a good reference for the flexural design of the prestressed CSW-UHPC composite box girders.

Miaoziping Bridge, a long-span rigid-frame bridge, uplift appeared at the end spans in the 2008 Wenchuan earthquake. Bearings and pad stones were damaged during the earthquake. In the past, the uplift mechanism and the seismic response under near-fault and far-fault ground motions were not sufficiently recognized. Here, a refined finite-element model of the Miaoziping Bridge was established considering the initial stress state and the nonlinear characteristics of the girder (e.g., cracking of concrete). The Wenchuan strong motion records and other 40 near-fault pulse-type and 40 far-fault ground motions were selected for nonlinear time history analysis. The uplift effect was realized by considering the compressive-only behavior of bearings. The results show that the seismic responses of the bridge under Wenchuan earthquake ground motions are in good agreement with the real seismic damage observed after the Wenchuan earthquake. The excitation of the near-fault pulse-type ground motion along the longitudinal direction is the dominant factor of the uplift at the end spans. When peak ground acceleration of the near-fault pulse-type ground motion is greater than 0.3g, the end spans are prone to uplift, and the maximum uplift displacement responses can reach 50 cm. There is little uplift possibility subjected to the far-fault ground motions. When the pulse period is in the range of 1–3 s, the pulse effect equals or even exceeds the full-wave effect. The end spans can hardly uplift subjected to vertical or transverse excitation individually. There is a slight difference between the uplift displacements subjected to single longitudinal ground motions and three-directional ground motions. The time of maximum uplift displacement is delayed considering the wave-passage effect. When the wave velocity is less than 1,000 m/s, the adverse effects of the wave-passage effect may be considered.

This paper presents and discusses the feasibility of complete model updating of cable-stayed bridges using experimental estimates of the cable forces and modal parameters. The procedure is applied to the model updating of a curved cable-stayed bridge in Venice (Italy). Conventional optimization problems of mass and stiffness using ambient vibration data are prone to ill-posedness and ill-conditioning. Generally, the scholar must assume one of the two to achieve a trustworthy optimization. This paper demonstrates that it is possible to assess a large set of parameters affecting the mass and stiffness of a cable-stayed bridge following a step-wise procedure based on ambient vibration tests. Preliminary variance-based sensitivity analysis supports the reduction in the number of parameters to be calibrated. Then, the selected parameters are tuned using a meta-heuristic optimization algorithm. In the considered case study, the sensitivity analyses highlight the significance of the following: the concrete mass, the vertical stiffness of the bearings, and the concrete Young’s modulus of the deck and the tower. However, optimizing all the unknowns using a single objective function does not lead to optima within the search domain. Therefore, the authors show that a three-step optimization is required in the considered case study to achieve convergence within the parameters’ space. As a result, all the twelve modes of the calibrated model perfectly match the experimental ones, with the modal assurance criterion (MAC) higher than 0.9. In addition, the cable forces of the calibrated model present a good match with the experimental ones, with an average percentage error equal to 11%.

For arch bridges built on deep soil sites, significant seismic amplification effects were observed in the overlying soil layer from past earthquake events, and these effects can lead to more serious structural damage. Grouting-strengthening technology has recently been recommended as an innovative geotechnical method for strengthening soils to retain the seismic amplification phenomenon under strong ground motions, and it has exhibited advantages in improving the lateral resistance of soils. However, grouting reliability depends on the soil type, jet pressure, and engineering costs, and there has been little research on the differences in the natural period and seismic capacity caused by grouting behavior. To fill this research gap, based on a practical engineering prototype, shaking table tests were performed for semigrouting and all-grouting cases in sandy-gravel soil with a simple bridge abutment to investigate the difference in the seismic capacity of the two soil–foundation–abutment systems. The acceleration response difference between the grouting zone and the surrounding soil, characteristic periodic variation of the response spectrum of the soil and abutment, grouting depths, and seismic energy dissipation mechanism of the soil were analyzed. The results show that the acceleration amplification factor of the all-grouting foundation was smaller than that of the semigrouting foundation. However, the acceleration amplitude of the all-grouting foundation was larger owing to the higher seismic input energy. Significant differences in the lateral resistance mechanism between semigrouting and all-grouting foundations were observed. The grouting foundation realizes consistent acceleration and displacement through load transmission and soil–structure interaction mechanisms. The results demonstrate the suitability of soil thicknesses for significantly reducing the seismic demands of abutments and provide guidance for foundation treatment methods in relevant engineering projects.