Journal of Bridge Engineering

Flood events bring havoc to transportation assets including bridges, culverts, and roadways on an annual basis. This has been an increasing trend in the recent years, especially in Midwestern states. Millions of dollars are spent to repair or replace transportation infrastructure every year due to damage suffered from floods. With a major drive within transportation agencies to consider the risks associated with transportation asset damages, and provide optimized plans for pre-event mitigation and postevent recovery, there is a need for better estimation of the type of damages observed after inland flood events and the associated costs for the repair and recovery of these damages. Most previous studies have focused on recovery after earthquakes, which by nature imposes a different organizational and response effect on the agencies. The limited number of studies on other hazards such as coastal flooding is based on sparse survey data. This paper specifically aims to address the existing gap in the availability of data on damages and costs that are observed after actual inland flood events. For this purpose, the damage patterns associated with scour, high water levels, debris accumulation, abutment wash out, and other damages have been identified. The extreme flood events throughout a 16-year span (1998–2014) that were documented as part of the emergency relief funds have been considered. Repair tasks associated with each damage mode are identified based on actual project documents and costs are broken down by each of these tasks. This component by itself is a leap forward in collection of types of damages and associated costs for inland flood events. In addition, generalized linear models are conducted to identify the relationships between flood stage, bridge characteristics, and damage level using both Gaussian and binomial distributions of the responses. Analyses shows that the maximum water elevation at a bridge location is statistically significant in determining the probability of bridge damage. There are also many other bridge attributes including length, width, skew angle, and pier width that have a correlation to different damage modes of bridges. A series of National Bridge Inventory condition ratings are analyzed with the scour criticality rating and superstructure rating both being significant predictors in the probability of multiple bridge damage modes. This paper is the first known effort aims at identifying the type of damages associated with inland flood events, the associated repair tasks, and costs of recovery through a coordinate data collection effort from actual events and completed projects and is expected to majorly contribute to future studies aimed at assessing the resilience of transportation infrastructure under inland flooding events by providing better estimates of the recovery tasks and costs.

The condition of substructures in high-speed railway (HSR) bridges is crucial to the safety of the railway operation. However, research on the condition evaluation of substructures in HSR bridges is very limited. In this paper, a simplified model for a single pier that considers the effect of a pier–beam coupling will be proposed to simulate the multiorder vibrations in the local pier–beam system by distributing the mass of the beam to the top of the adjacent piers. A systematic procedure that is based on the simplified model and finite-element (FE) model updating will be adopted for the modal analysis and condition evaluation of the bridge substructures. Numerical simulations will be conducted on a 10-span simply supported HSR bridge to validate the proposed model and method. Furthermore, field measurements will be conducted on an HSR bridge to assess the health condition of the substructures. The results show that the modal frequencies and damage that were identified with the simplified model agreed well with those of the local pier–beam system. The proposed simplified model could be suitable for the modal analysis and condition evaluation of HSR bridge substructures.

The results of an experimental program comparing the responses of shear-critical rectangular columns tested under monotonic and reversed-cyclic loading are presented. These specimens had a constant compressive axial load and varying amounts of transverse reinforcement. Comparisons of the monotonic and reversed-cyclic loading responses are discussed. The reversed-cyclic peak shear strengths were about 11% and 17% lower, on average, than the monotonic peak strengths for the positive peak and the negative peak, respectively. Response predictions were made for columns from this experimental program, as well as for tests by other researchers, on rectangular shear-critical columns. Prediction methods included those based on current load and resistance factor design (LRFD) standards and seismic guidelines with and without an included strut, as well as nonlinear finite-element analysis. Methods based on official standards and guidelines gave similar conservative results for the shear strength. It was concluded that the addition of the horizontal components of inclined struts associated with the compressive axial loads to the sectional predictions improved the strength predictions by about 37% on average. In addition to providing accurate shear strength predictions, nonlinear finite-element analysis is capable of predicting the complete member response and accounts for the combined contributions of the concrete, transverse reinforcement, and inclined strut action from the applied axial compressive load.

This study proposes an integrated and easily applicable framework that considers the dynamic effect of sudden member loss to identify the critical members in steel truss bridges through nonlinear dynamic analysis. Numerical simulations of sudden member removal in truss bridges through nonlinear dynamic analysis requires significant computational resource because of the modeling of truss members by shell or solid elements. The proposed approach simulates both yielding and buckling behavior of truss members following sudden removal of a member by modeling truss members using the Hughes–Liu (H-L) beam formulation in LS-DYNA. The approach was demonstrated to be computationally efficient, while preserving the accuracy of the numerical results. The reliability and accuracy of the modeling using the H-L beam formulation were verified through three examples of varying degrees of complexity. The capability of the proposed approach in identifying critical members was demonstrated through a case study of the Aby Bridge (a simply supported truss bridge that was originally designed as a fracture critical bridge).

Many bridges would be washed away due to giant tsunamis caused by the anticipated Nankai Trough earthquake. The accelerated bridge construction (ABC) concept should be applied to temporary bridge construction to save on-site construction time and help roads reopen immediately after the event. In this paper, a temporary bridge using precast reinforced concrete (RC) blocks with connections composed of steel shear keys and carbon fiber–reinforced polymer (CFRP) sheets is proposed. The proposed bridge facilitates rapid recovery from natural disasters and accordingly enhances disaster resilience. Bending and shear tests are conducted to investigate the effects of the proposed connection on the structural performance of beams. The experimental results indicate that the connection with an adequate CFRP sheet length provides sufficient flexural capacity for temporary bridges and does not negatively affect the shear capacity. Moreover, a 3D finite-element (FE) model is applied to simulate the bending tests. The FE model provides good agreement with the experimental results and can be applied to design the structural details of full-scale RC blocks.

As-built bridge piers are likely to be subjected to vehicular collisions, causing severe damage to the bridge substructure and even resulting in the collapse of the entire bridge. This study aimed to evaluate the effectiveness of fiber-reinforced polymer (FRP) strengthening in enhancing the vehicular impact resistance of as-built bridge piers. A typical local, refined finite-element (FE) model of a simply supported two-span, double-column, reinforced-concrete (RC) bridge was established. The adopted material constitutive models and the FE analytical approaches were then validated through reduced vehicle model lateral impact tests on bare and carbon fiber–reinforced polymer (CFRP)-strengthened RC columns. The effective schemes for FRP strengthening of bridge piers against vehicle impact are discussed from the aspects of fiber orientation, number of layers, and strengthened height as well as by FRP type. Based on the FRP strengthening scheme, 48 vehicle–bridge collision scenarios were designed to evaluate the collapse of bridges with/without FRP-strengthened piers. It was found that (1) external FRP wrapping can effectively enhance vehicular impact-resistance of as-built bridge piers (e.g., reducing the degree of damage and deformation of the impacted pier); (2) for typical bridge piers, the effective strengthening scheme comprised a fiber orientation of 0° in reference to the circumferential direction, a 3-m strengthened height, and four-layer CFRP wrapping; (3) compared with bare bridge piers, FRP-strengthened piers could improve the vehicular impact-resistant safety redundancy of as-built bridges and, to some extent, avoid bridge collapses under truck collisions at high speed. Furthermore, through introducing the dynamic increase factors of concrete strength, reinforcement rebars, and FRP, and considering the nonuniform distributions of the strain rate of FRP-strengthened bridge piers caused by vehicular collision, the dynamic shear capacity of strengthened bridge pier was formulated.

This paper numerically investigates the dynamic behavior of bridge piers reinforced with shape-memory alloy (SMA) rebar when subjected to lateral impact loads. Performance of SMA reinforced pier is compared with column reinforced by conventional steel rebar by performing finite-element (FE) simulations in LS-DYNA. The impact performance of the columns is evaluated by considering variations in different structural- and loading-related parameters including the type of SMA rebar, the length of SMA rebar (L_SMA), the impact velocity (V_imp), and the axial load ratio (ALR). From the FE simulations, it is found that the use of SMA rebars at the plastic hinge regions and the impact loading height of the columns significantly enhances the impact resistance and the recoverability of the columns by reducing their damage levels and residual displacements. Also, the failure modes of the columns tend to govern by flexure by using SMA rebars, and the columns reinforced with Cu-based (Cu–Al–Mn) SMA rebars are more likely to fail in flexural modes compared to those reinforced with Ni-based (Ni–Ti) SMA rebars. However, the negative influences of SMA rebars on the impact resistance of the columns are found when L_SMA exceeds 0.5 under impact loads with velocities greater than 15 m/s. In addition, an ALR greater than 0.1 considerably increases the impact resistance of the columns.

Stay cables are crucial components in cable-stayed bridges. The time-varying cable tension is an important indicator for the condition assessment of cables because the variation in tension will cause fatigue damage. This paper proposes an adaptive identification method for time-varying cable tension based on an improved variational mode decomposition (VMD) algorithm. In the proposed method, the cable vibration signal is decomposed by improved VMD to identify the time-varying modal frequencies by the Hilbert transform, and then the time-varying cable tension is calculated by the vibration method. To realize adaptive and accurate identification, the VMD algorithm is improved by optimizing parameters: the number of decomposed modes is determined by the characteristic that frequency differences between the adjacent modal frequencies of the cable vibration signal are equal, and the balancing parameter is optimized by constructing an evaluation index and searching for the minimum of the index. A numerical simulation illustrates that the accuracy of the proposed method is satisfactory. To verify the practicability of the proposed method, the monitoring data of a single tower cable-stayed bridge are used. The results demonstrate that the proposed method is a practical and reliable method to identify the time-varying cable tension.

To achieve a high-efficiency impact test for deck flexibility identification of bridges, a reference-free substructuring test strategy with a two-stage integration method is proposed, which can be adopted to integrate the isolated parameters extracted from the measured data of each substructure divided from the entire bridge deck. As full-structural testing is fragmented into several small-scale independent substructuring tests without overlapping transitional areas, testing becomes more flexible, and experimental costs are greatly reduced while obtaining the same flexibility identification results as traditional full structural testing. Three crucial steps are addressed in this study. In the first phase, the combined deterministic-stochastic subspace identification algorithm is adopted in order to extract the modal parameters of each substructure. Subsequently, the stiffness matrix weighted orthogonality of the mode shapes is employed as the index of the parameter integration to preliminarily screen the submode shape combinations. Finally, the mode surface polynomial degree index is constructed to further screen the correct combination for the entire structural flexibility integration. Two simulation examples and an experimental example are finally considered to verify both the feasibility and the effectiveness of the proposed method.

In simulating engineering structures, the uncertainty quantification and propagation (UQ&P) of model parameters is of paramount importance for model verification and validation (V&V), the fidelity of which has been proven to have a prominent effect on structural safety assessment and decision making. In this study, the parametric uncertainties due to environmental periodicity were inversely quantified in form of intervals through a V&V framework based on the conjunction of interval response surface method (IRSM) and probability box (P-Box), which is adaptable and efficient for real bridge structures. The uncertainties of temperature were first quantified with P-Box, based on a year’s worth of data obtained from the structural health monitoring (SHM) system of a cable-stayed bridge. Following that, the uncertainties of structural frequencies were quantified through a correlation analysis between temperature and frequencies which were filtered by different techniques. The expressions of IRSM were constructed and verified, with frequencies calculated from them agreeing well with those calculated from the finite-element (FE) model simulation. Thereafter, the interval boundary values of the observed frequencies were obtained by searching the tails of the P-Box bounds, thus providing the target intervals for model validation. The parametric intervals were validated efficiently through a two-step calibration procedure based on monotonic analysis. The result shows that the validated model has a good predictive capacity and could serve as a high-fidelity model for further application, with the parametric uncertainties appropriately considered in the form of intervals.

Many concrete bridges around the world have passed their service life and are at high risk of collapse, especially in active seismic regions. This is particularly true in many developing and underdeveloped countries, where deficient construction and underpreparedness would result in a major catastrophe should a major seismic event occur. Thus, there lies a need to introduce an efficient, cost-effective, and readily available method of bridge rehabilitation. In this study, steel-reinforced grout (SRG) jacketing is used as a seismic strengthening technique for reinforced concrete bridge piers. Two bridge piers, one seismically damaged and one seismically deficient, were jacketed with SRG and then tested to observe their seismic response. The findings from the experimental program revealed that SRG jacketing can rehabilitate/repair a damaged bridge pier, and restore its flexural capacity, energy dissipation capacity, and ductility. While strengthening a seismically deficient pier, results showed that the flexural capacity and energy dissipation capacity could be improved, and ductility could be enhanced.

With the increase in the main spans of cable-stayed bridges, the wind-induced vibration, especially the high-mode vortex-induced vibration (VIV) of the long stay cables has become a concern for many researchers. In this study, to investigate the high-mode VIVs of stay cables via wind tunnel tests, the mode order amplification factor (MOAF) of the stay cable was proposed to design the flexible stay cable model with a relatively large-scale ratio (λ_Re) of the Reynolds number (Re). Furthermore, the wind-induced vibration characteristics of the flexible stay cable model with a smooth surface for wind yaw angle (β) of 0° were investigated. In addition, the β effects on the wind-induced vibration characteristics of the stay cable were studied. Finally, double-helical fillets were applied to suppress the high-mode VIV responses of the flexible stay cable model for different β. The results showed that the flexible stay cable model that was designed by the proposed method of MOAF satisfied the similarity of the prototype stay cable and the damping ratios (ξ) of the first several modes of the flexible stay cable model were from approximately 0.021% to 0.064%. The stay cable exhibited five in-plane VIVs in the test wind velocity (V) range for β = 0°. Furthermore, the maximum amplitude of the displacement of the in-plane VIV of the flexible stay cable model decreased with the increase in the VIV mode order. The significant in-plane VIV responses of the stay cable were observed for β of 15°, 30°, −15°, −30°, and −45°, respectively, and the in-plane vibration acceleration responses were significantly larger than the out-of-plane vibration acceleration responses of the flexible stay cable model. The VIV responses of the stay cable could be effectively suppressed through the double-helical fillets with a diameter (d) of d = 0.10 D (where D = diameter of the stay cable) and pitch (P) of P = 12 D.

Risk assessment of arch bridges can be beneficial for making informed choices following an earthquake by addressing the most vulnerable components. Although several researchers have studied the seismic vulnerability of ordinary bridges, there is a scarcity of in-depth investigation of the seismic performance of arch bridges for both the capacity and demand sides. This paper studies the component- and system-level vulnerability of concrete open-spandrel deck arch bridges by identifying significant geometrical and design attributes through the application of parametric screening. A strain-based approach is presented to determine the component damage state thresholds owing to the insufficiency of detailed information on different component damage levels of open-spandrel deck arch bridges. Two categories of arch bridges with different superstructure-substructure connection types, including monolithic and non-monolithic connections, together with four rise-to-span ratios for each bridge category were considered. Detailed nonlinear three-dimensional analytical models representing the vulnerability of major bridge components as well as the uncertainty in modeling parameters were developed, and fragility analysis was performed by applying nonlinear time history analysis. Results exhibited the predominant role of the connection type between the deck and substructure as well as the rise–span ratio on the failure probability of arch bridges. Arch bridges with a non-monolithic superstructure–substructure connection type revealed more vulnerability at lower damage levels compared with arch bridges with the monolithic connection, while an opposite trend is observed in higher damage states. In summary, arch bridges with the non-monolithic connection type demonstrated enhanced seismic performance regarding the functionality and vertical stability of the bridge.

The incorporation of expansion joints in the parapet wall of bridge girders is standard practice to account for factors such as temperature differentials, shrinkage, and settlement. Gaining an understanding of the influence of expansion joints in bridge parapets is important, since the overall service performance and integrity of the bridge can be significantly influenced by the presence of expansion joints in parapets. This study investigated the flexural behavior of the bridge girder considering the effects of the expansion joint through experimental testing and numerical analyses. Effects of the expansion joint on flexural stresses and on the migration of the neutral axis of the exterior girder were investigated. Both the cracking pattern of the girders subjected to pure flexure and the ultimate flexural capacity were also examined. Compared with the benchmark specimen without the parapet and expansion joint, it was found that the plane cross section assumption cannot be applied to the cross section at the expansion joint. The stress distribution across the section height is nonlinear, with amplified compressive stresses at the top and lower tensile stresses at the bottom than for the benchmark girders. Diagonal cracks occurred and propagated toward the expansion joint at the pure flexure region. Though the flexural capacity of the single girder was slightly increased, the actual load-carrying capacity of the serviced exterior box girder with the expansion joint was substantially decreased.

The belowground portion of extended pile-shaft-supported bridges is usually prone to earthquake-induced damage during earthquake shakings. The unobservable pile damage below the ground surface makes it difficult and time-consuming to estimate the functionality loss of these damaged bridges and decide whether to reopen them for emergency traffic after an earthquake. Therefore, the reliable and rapid evaluation of the postearthquake vertical load-carrying capacity of extended pile shafts is essential for postearthquake recovery. To this end, one extended pile-shaft specimen in homogeneous sand was first subjected to the lateral cyclic loads applied to the column head in the laboratory to simulate earthquake loads. A pushdown test was then performed on this laterally damaged specimen to determine its residual vertical load-carrying capacity. After that, a finite element model based on the beam on a nonlinear Winkler foundation (BNWF) for the quasi-static test was built and validated using the experimental data. Finally, a comprehensive parametric study was carried out to investigate the postearthquake vertical load-carrying capacity of extended pile shafts, exhibiting a lateral residual displacement, considering the variation of structure and soil parameters. After that, a continuous loss model for the vertical load-carrying capacity of the extended pile shafts in cohesionless soils was developed. Results indicate that the ratio between the height of the aboveground column and the column diameter had a considerable impact on the residual vertical load-carrying capacity due to the P-Delta effect. The greater the ratio, the faster the normalized vertical strength degradation rate. The relative and mass densities of sandy soil and concrete strength had an insignificant impact on the normalized vertical strength. The relationship between the normalized vertical strength and the pile curvature ductility and the residual column drift ratio was described using piecewise linear regression models in logarithmic space, respectively. Based on the loss model, multilevel limit values of the peak pile curvature ductility and the residual column drift ratio were recommended for different traffic capacity levels of extended pile-shaft-supported bridges. This research represents a first step toward developing a rapid postearthquake assessment approach for the extended pile-shaft-supported bridges.

This case study proposed and evaluated an approach to repair post-tensioned prestressed concrete bridge girders in cold regions. The girders had severe frost-heaving cracks and unhardened cementitious grout in the prestressing ducts. Three full-scale girders were retrieved from a real highway bridge located in the Tibetan Plateau. The girders were repaired with two types of polymeric adhesives and evaluated through borehole and anatomy examinations and flexural tests after repairing. The results of the borehole and anatomy examinations of the damaged and repaired girders showed that polymeric adhesives filled the ducts and cracks. Flexural test results showed that the repairing significantly enhanced the load capacity, ductility, and crack resistance of the bridge girders. The mechanisms of the improvement in flexural properties due to the repairing are discussed. This research offers practical solutions and insights into the mechanisms for the repairing of post-tensioned prestressed concrete girders with frost-heaving damage.