In the present study, the incremental modal pushover analysis (IMPA), a pushover-based approach already proposed and applied to buildings by the same authors, was revised and proposed for bridges (IMPAβ). Pushover analysis considers the effects of higher modes on the structural response. Bridges are structurally very different from multi-story buildings, where multimodal pushover (MPA) has been developed and is currently used. In bridges, consideration for higher modes is often necessary: The responses of some structural elements of the bridge (e.g., piers) influence the overall bridge response. Therefore, the failure of these elements can determine the failure of the whole structure, even if they give a small contribution total base shear. Incremental dynamic analysis (IDA) requires input accelerograms for high intensities, which are rare in the databases, while scaling of generated accelerograms with a simple increment of the scaling acceleration is not appropriate. This fact renders IDA, which is by its nature time-consuming, not straightforward. On the contrary, the change of input spectrum required by IMPA is simple. IMPAβ also utilizes a simple complementary method coupled to MPA, to obtain bounds at very high seismic intensities. Finally, the two incremental methods based on static nonlinear and dynamic nonlinear analyses are compared. Full article

Vibration-based monitoring was performed on a short-span skewed highway bridge on the basis of wireless measurements. By means of operational modal analysis, highly accurate modal results (frequencies and mode shapes) were extracted by using a self-developed wireless acquisition system, for which the performance was verified in the field. In order to reproduce the experimental modal characteristics, a refined finite element model was manually tuned to reduce the idealization errors and then updated with the sensitivity method to reduce the parametric errors. It was found that to build a reliable Finite element (FE) model for application in structural health monitoring, the effects of superelevation and boundary conditions of a skewed bridge should be taken into account carefully. Full article

This paper discusses the seismic behavior of reinforced concrete (RC) bridge structures, focusing on the shear–flexure interaction phenomena. The assessment of reinforced concrete bridges under seismic action needs the ability to model the effective non-linear response in order to identify the relevant failure modes of the structure. Existing RC bridges have been conceived according to old engineering practices and codes, lacking the implementation of capacity design principles, and therefore can exhibit premature shear failures with a reduction of available strength and ductility. In particular, recent studies have shown that the shear strength can decrease with the increase of flexural damage after the development of plastic hinges and, in some cases, this can cause unexpected shear failures in the plastic branch with a consequent reduction of ductility. The aim of the research is to implement those phenomena in a finite-element analysis. The proposed model consists of a flexure fiber element coupled with a shear and a rotational slip spring. The model has been implemented in the OpenSEES framework and calibrated against experimental data, showing a good ability to capture the overall response. Full article

Hangers are important tensile members in half-through arch bridges and through arch bridges (HTABs and TABs). The floating deck structures of HTABs and TABs will commonly produce longitudinal deformation and rotate under the effect of temperature and the temperature gradient, which will cause bending deformation at anchorages of fixed-end hangers. This bending deformation can generate adverse bending stress for hangers and decrease the strength and fatigue properties of the seven-wire strands in the hangers. Firstly, theoretical derivation and finite element analysis are conducted to study the bending stress of hangers that is caused by bending deformation. We find that bending stress of hangers is mainly generated by lateral bending caused by the difference in longitudinal displacement at both ends of the hangers under the effect of temperature. Subsequently, the ultimate tensile strength of the seven-wire strands under lateral bending is obtained by FEM and an experimental study. The ultimate tensile strength of the seven-wire strands could decrease by 23.3% when lateral bending is considered. Moreover, the relationship between the fatigue properties of the seven-wire strands and lateral bending is obtained based on observing the ultimate tensile strength under lateral bending. Lateral bending significantly influences the fatigue properties of the seven-wire strands. When the lateral bending angle reaches about 50 mrad, the fatigue resistance of the seven-wire strands drop by almost 40%. The considerable decrease in the strength and fatigue properties of the seven-wire strands indicates that lateral bending has a significant adverse influence on hangers that consist of seven-wire strands. Finally, it is advised to use the tied arch structure for HTABs and TABs to mitigate the adverse influence of lateral bending on hangers. Full article

In this study, engineered cementitious composite (ECC) was used as a deck paving for long-span bridges. The feasibility of using an epoxy adhesive to achieve wet-bonding between a steel deck and cast-in-place ECC was evaluated. The shear and pull-off tests were conducted to evaluate the effects of freeze-thaw cycles and hydrothermal aging on interfacial properties. The test results indicate that the interfacial strength decreases with an increase in the number of freeze-thaw cycles and the duration of hydrothermal aging. Based on an inclined shear test, a criterion for interface failure under the combined action of shear and compression is also proposed. Wet-bonding technology might promote the application of ECC in the surfacing system for orthotropic steel deck bridge and further extend the service life of a bridge structure. Full article

The use of wood in the construction of bridges has increased in recent decades thanks to the characteristics of this material, i.e., environmentally-friendly and suitability within natural landscapes. Nevertheless, timber constructions may be affected by degrading effects due to biological and/or abiotic agents, and may be exposed to impacts or vibrations due to external forces such as wind, earthquakes or walking pedestrians. Consequently, bridge performance with respect to these aspects should be assessed from the early design stage. Within this context, in this study, some shape, structural and durability strategies dealing with the design of timber bridges for pedestrians are investigated in order to extend the service life of these constructions. More precisely, a methodology consisting of three steps, to be applied at the early conceptual design stage, is proposed. The three fundamental steps to be considered in the preliminary design of timber bridges are: (i) main boundary constraints and load-bearing system; (ii) durability; (iii) vibration levels. In the study, the presented methodology is applied and described for the design of a pedestrian and cyclist timber bridge over the Gravina torrent, in Apulia (Italy). Full article

Circular steel tube members with the absence of anticorrosive protection or coating failure are prone to uniform corrosion, which threatens the reliability and safety of members in the atmospheric environment. To fully study the mechanical behavior of uniformly corroded circular steel tubes, compression test and theoretical analysis were conducted, and two methods considering section reduction and material degradation, respectively, were adopted for the calculation of ultimate load carrying capacities of specimens. The results indicate that uniform corrosion did not change the failure modes of specimens, and all of them belonged to global buckling failure. The load carrying capacities and stiffness of specimens decreased with the increase of corrosion ratio, and the degree of reduction was greater than that of material degradation, showing a linear relationship with the corrosion rate. Under the same corrosion ratio, the specimens with larger eccentricity represented more obvious load carrying capacity and stiffness degradation. The load carrying capacities predicted by both methods were in good agreement with the test results and had a certain safety margin. The conservative degree of calculation results from three specifications followed a descending order of ANSI/AISC 360-16, GB 50017-2017, and EN 1993-1-1. Under the same corrosion ratio, the load carrying capacity variation of specimens between one-sided corrosion and two-sided corrosion was less than 3%. Full article

Grouted connections are commonly used in marine engineering, especially on oil platforms, cross-sea bridges, and offshore wind power turbines. The prediction methods for axial carrying capacity of grouted connections with shear keys and their application ranges in current codes were analyzed in this paper. The calculated results by using different codes were compared based on a practical grouted connection between steel piles and the jacket foundation of a wind turbine. The research team conducted axial compression tests on seven specimens, collected a wide range of experimental results to establish a database, and finally compared the standard calculation results with the experimental results. The study indicates that the axial strength of grouted connections predicted by different methods is distinct. The calculation formula of the British Health and Safety Executive (HSE, 2002) has obvious limitations; specifically, with increased shear keys, strength is overestimated, resulting in insecure design outcome of structures. The results calculated by the Norwegian Det Norske Veritas (DNV, 2013) are generally consistent with the experimental results, in which the reduction effect of multiple shear keys was considered. The prediction method of the American Petroleum Institute (API, 2007), which undervalues the bearing performance of connections, is excessively conservative. The method of the combined Norwegian and German Det Norske Veritas–Germanischer Lloyd (DNV-GL, 2016) has wider applicability and is safe, reliable, and economical. Full article

In accelerated bridge construction (ABC), prefabricated bridge deck elements are merged using “closure joints.” Because of the cast-in-place nature of closure joints that are expected to go into service rapidly and problems observed for some types of closure joints, there have been some concerns about their long-term durability. This has necessitated the need for monitoring the condition of ABC closure joints using non-destructive testing (NDT) methods. Closure joints contain unique features and details that sets them apart from conventional deck panels. This requires a special treatment of closure joints when it comes to selecting the appropriate NDT technique for their health monitoring. A clear guideline for selecting an applicable NDT method for various types of closure joints has not been developed yet. For this purpose, an investigation was carried out in the Accelerated Bridge Construction University Transportation Center (ABC-UTC) at Florida International University. This paper summarizes the result of this investigation. It includes reviews of all relevant NDT methods for applicability to ABC closure joints and efforts for categorizing closure joints according to joint features that affect the use of NDT. Since the applicability of NDT methods heavily depend on the type of expected anomaly to be detected and its root causes, all potential defects and types of damage were identified and investigated using a damage sequence tree (DST). Consequently, damage etiology for ABC closure joints were established using fault tree analysis (FTA). Finally, a quantitative statistical survey was used to substantiate the selection of the NDT methods that were most applicable to the health monitoring of ABC bridges containing closure joints. The results presented in this paper can be used by bridge owners and consultants as an effective and practical guide for the selection of NDT methods for monitoring the health of ABC closure joints. Full article

Fatigue load models for road bridges given in the Eurocode EN1991-2 have been calibrated considering real traffic measurements that became available around 1990. Since then, traffic composition has evolved considerably, also considering the issuing of the 96/53/EC Directive, which legitimated member states, on an equal and not discriminatory basis, to allow the circulation of Long and Heavy Vehicles (LHVs). Thus, the appropriateness of fatigue load models to cover also the effects of these vehicles, which are longer, heavier and potentially more damaging than common Heavy Goods Vehicles (HGVs), became an issue. The aim of the study is to assess how the evolution of European traffic influences the fatigue assessment of bridges. To capture the essence of the problem, three different real traffic measurements are compared in terms of fatigue damage: the Auxerre (FR) traffic, adopted to define fatigue load models in EN1991-2; the Moerdijk (NL) traffic, characterized by a high percentage of LHVs; and the Igualada (ES) traffic. To assess the current relevance of fatigue load models LM2 and LM4 of EN1991-2, the aptitude of these models to adequately reproduce the effects caused by LHVs is discussed in detail. The results demonstrate that the Auxerre traffic is still the most onerous; that the Moerdijk traffic is generally more severe than the Igualada traffic, and that the fatigue load models of Eurocode do not require major updates. The study is further supplemented by investigating the suitability of the formulae provided in the Eurocodes for the damage equivalence factors λ2 and λ3 to express the influence of the total lorry volume on the fatigue damage. In that latter case, the conclusion is that the formulae proposed in the Eurocodes, based on the assumption of a linear fatigue strength S–N curve with constant conventional slope m, could lead to erroneous, even unsafe, estimates of the fatigue life, especially when details are characterized by constant amplitude fatigue limit ΔσD, thus calling for further improvements of the formulae themselves. Full article

Soil-abutment or soil-pile interactions under cyclic static loads have been widely studied in integral abutment jointless bridges (IAJBs). However, the IAJB has the combinational interaction of soil-abutment and soil-pile, and the soil-abutment-pile interaction is lack of comprehensively study. Therefore, a reciprocating low-cycle pseudo-static test was carried out under an cyclic horizontal displacement load (DL) to gain insight into the mechanical behavior of the soil-abutment-pile system. Test results indicate that the earth pressure of backfill behind abutment has the ratcheting effect, which induced a large earth pressure. The soil-abutment-pile system has a favorable energy dissipation capacity and seismic behavior with relatively large equivalent viscous damping. The accumulative horizontal deformation in pile will be occurred by the effect of abutment and unbalance soil pressure of backfill. The test shows that the maximum horizontal deformation of pile occurs in the pile depth of 1.0b~3.0b of pile body rather than at the pile head due to the accumulative deformation of pile, which is significantly different from those of previous test results of soil-pile interaction. The time-history curve for abutment is relatively symmetrical and its accumulative deformation is small. However, the time-history curve of pile is asymmetrical and its accumulative deformation is dramatically large. The traditional theory of deformation applies only to the calculation of noncumulative deformation of pile, and the influence of accumulative deformation should be considered in practical engineering. A significant difference of inclinations in the positive and negative directions increases when the displacement load is relatively large. The rotation of abutment when bridge expands is larger than that when bridge contracts due to earth pressure of backfill. Full article

The accuracy of the finite element model (FEM) for concrete closed girder cross-sections is significantly influenced by thermal boundary conditions. The internal thermal boundary conditions can be simulated by inputting the convection heat transfer coefficient and the temperatures inside the cavities or by establishing air elements in the FEM. In order to analyze the influence of different simulation methods for the internal thermal boundary conditions on temperature distributions for concrete closed girder cross-sections, the temperature distributions on the cross-sections of a box girder, small box girders, and adjacent box girders were monitored, and the corresponding FEMs were implemented. By comparing the temperature data obtained from the field test and FEMs, the numerical hourly temperature curves calculated by using the measured temperatures inside the cavities provide the closest agreement with the measured results; however, the measurements of the temperatures on site are cost- and time-prohibitive. When there is a lack of measured temperatures inside the cavities, the numerical hourly temperature curves calculated by establishing air elements in the FEM provide the closest agreement. The influences of different simulation methods for the internal thermal boundary conditions on the highest hourly average effective temperatures and the trends of the vertical temperature gradients for concrete closed girder cross-sections were small. The FEM with air elements can be adopted to analyze the temperature distributions on concrete closed girder cross-sections under historically extreme temperature conditions. It can be predicted that the longitudinal thermal movement of concrete closed girders would be underestimated by considering variations in the one-year measured average effective temperature of the cross-sections or the Chinese-code-specified design effective temperature for the highway bridge structures, which are thus unconservative for engineering applications. The Chinese-code-specified design vertical temperature gradients are conservative for the bridge deck surface and unconservative for the bottom flange. Full article

The large portfolio of aging highway bridges worldwide includes many reinforced concrete T-section beams with various levels of damage and degradation. However, there is currently dearth of research on the anchoring behavior of CFRP sheets used for strengthening such RC T-section beams. Moreover, there is a need for rational and accurate analytical models to predict the strengthening effect of CFRP sheets for RC T-section beams. In this study, eight RC T-section beam specimens strengthened with externally bonded CFRP sheets were tested under quasi-static loading. The failure mode, cracking resistance, yielding and ultimate capacity were examined. The effects of U-wrap spacing, flexural reinforcing ratio, and concrete compressive strength on the flexural behavior of the CFRP strengthened RC T-section beams were analyzed and discussed. New analytical models were developed to predict the cracking, yielding and ultimate load resistance of the RC T-section beams strengthened with CFRP sheets. The analytical models were validated through comparing its predictions with experimental results, and they demonstrated adequate accuracy. The findings could be deployed for the retrofitting of a large portfolio of aging highway bridges with deteriorated reinforced concrete T-section beams. Full article

This study aims to establish a probabilistic capacity model of a wall pier under various damage states, and the seismic vulnerability of a typical wall pier bridge is studied. The finite element analysis of the wall pier is carried out by using the layered shell element, and its accuracy is verified through the comparison with the experimental results. A series of wall pier samples are generated based on the survey data, and the corresponding finite element models are established. The hysteresis analysis is implemented to obtain the displacement drift ratio of each seismic performance point. A candidate capacity model with various factors is proposed, and the unknown parameters are estimated and filtered by the Bayesian method. One hundred and twenty bridge samples of a benchmark bridge are generated by considering the uncertainty of parameters, and the finite element models are established. The bridge samples and ground motions were matched by one-to-one correspondence for the nonlinear time history analysis, and seismic vulnerability models of bridge components and system are obtained. The results showed that the in-plane capacity of wall piers is mainly affected by axial compression ratio, shear span ratio, and vertical reinforcement ratio. The wall pier shows excellent behavior in the earthquakes. The capacity models of wall piers can be used for evaluating the damage states of wall piers, and obtaining the seismic vulnerability model of wall piers bridges to be used for future seismic risk assessment and retrofit prioritization. Full article

The corrosion of reinforcement caused by chloride ingress significantly reduces the length of the service life of reinforced concrete bridges. Therefore, the condition of bridges is periodically inspected by specially trained engineers regarding the possible occurrence of reinforcement corrosion. Their main goal is to ensure that the structure can resist mechanical and environmental loads and offer a satisfactory level of safety and serviceability. In the course of assessment, measuring the chloride content, through which corrosion could be anticipated and prevented, presents a possible alternative to visual inspections and corrosion tests that can only indicate already existing corrosion. It is hard to determine the cost-effectiveness and actual value of chloride content measurements in a simple and straightforward way. Thus, the main aim of the paper was to study the value of newly gained information, which is obtained when a chloride content in reinforced concrete bridges is measured. This value was here analyzed through the pre-posterior analysis of the cost of measurement and repair, taking into account different types of exposure and material properties for a general case. The research focus was set on the initiation phase in which there are no visible damages. A relative comparison of costs is presented, where the cost of possible reactive/proactive repair was compared with the maximum cost of measurement, while the measurement is still cost effective. The analysis showed a high influence of the initial probability of depassivation on the maximum cost of the cost-effective measurement, as well as a nonreciprocal relation of the minimum cost of cost-effective reactive repair with the measurement accuracy. Full article

An optimal maintenance scheduling strategy for bridge networks can generate an efficient allocation of resources with budget limits and mitigate the perturbations caused by maintenance activities to the traffic flows. This research formulates the optimal maintenance scheduling problem as a bi-level programming model. The upper-level model is a multi-objective nonlinear programming model, which minimizes the total traffic delays during the maintenance period and maximizes the number of bridges to be maintained subject to the budget limit and the number of crews. In the lower-level, the users’ route choice following the upper-level decision is simulated using a modified user equilibrium model. Then, the proposed bi-level model is transformed into an equivalent single-level model that is solved by the simulated annealing algorithm. Finally, the model and algorithm are tested using a highway bridge network. The results show that the proposed method has an advantage in saving maintenance costs, reducing traffic delays, minimizing makespan compared with two empirical maintenance strategies. The sensitivity analysis reveals that traffic demand, number of crews, availability of budget, and decision maker’s preference all have significant effects on the optimal maintenance scheduling scheme for bridges including time sequence and job sequence. Full article

The reinforced concrete (RC) circular element is usually simplified as slab one on the issue of chloride diffusion simulation, without considering the effect of the geometrical shape. In the paper, a modified slab diffusion model is proposed for circular section. A formulation for estimating the error caused by neglecting the effect of shape on chloride diffusion is derived. The formulation demonstrates that radius significantly affect the error. When shape is neglected, the effects of model parameters, including the diffusion coefficient, radius, cover concrete thickness and age factor, on the corrosion initiation time are investigated. The result shows the radius has a slight effect on calculating the corrosion initiation time compared with other model parameters. Furthermore, the influence of shape on estimating on reliability index for different service time is also discussed. A guideline is proposed for properly using the modified slab diffusion model instead of the original one to predict service life. Finally, the impact of the shape of the RC circular column on the durability design against chloride corrosion is studied. The design result when the column is simplified as a slab element indicates a lower required minimum concrete cover thickness. The minimum thickness should be improved by 5 mm as a conservative choice based on the result of the slab element. Full article

Fatigue cracks in orthotropic steel decks (OSDs) have been a serious problem of steel bridges for a long time. The structural stress approach is an important approach for fatigue life evaluation of welded structures. Firstly, two parameters and the mesh sensitivity of the stress-based integration equivalent structural stress approach (stress integration approach for short) are analyzed in this paper. Then, the applicability of the master S-N curve is verified based on experimental data of the deck-rib welding details in OSDs. Finally, the multi-scale finite element model (FEM) of Jiangyin Bridge is established, and the bridge fatigue life calculation steps based on the stress integration approach are given. The influence of the slope of the master S-N curve at high cycles on the bridge fatigue life is discussed. Further, the weld parameter influences on the bridge fatigue life are analyzed, as including the following: (1) The determination of the influence of the weld size changes caused by weld manufacturing errors on the bridge fatigue life; (2) the proposal of a new grinding treatment type, and the analysis of influence of the grinding radius on fatigue life; and (3) a comparison of the fatigue life of the deck-rib welding details under 80% partial penetration and 100% full penetration. The results show that the structural stress calculated by the stress integration approach does not change significantly with the parameters of the isolation body width $w$ and the distance $\delta$ between the crack propagation surface and the reference surface. To simplify the calculation, $\delta$ is set as 0, and $w$ can be set as the mesh size along the weld length direction. The mesh size of the stress integration approach is recommended as 0.25 times the deck thickness. The slope of the master S-N curve at high cycles significantly affects the bridge fatigue life, and a slope of 5 is reasonable. The weld parameter studies for the deck-rib welding details in the OSD of Jiangyin Bridge show that the change of weld size caused by manufacturing errors can obviously affect the bridge fatigue life, and the fatigue life of five different weld types varies from 51 years to 113 years. The new grinding treatment type, without weakening the deck, is beneficial to improving the bridge fatigue life. The fatigue life increases by approximately 5% with an increase of the grinding radius of 2 mm. The fatigue life of 80% partial penetration is slightly higher than that of 100% full penetration. Full article

Reinforced bar corrosion induced by chloride ingression is one of the most significant threats to the durability of concrete structures in marine environments. The concrete cover thickness, compressive strength, chloride diffusion coefficient, and surface defects of reinforced concrete in the Jiaozhou Bay sea-crossing railway bridge were measured. The temperature and relative humidity in the concrete and the loading applied onto the reinforced concrete were monitored. Based on the DuraCrete model, a revised model for the service life prediction of concrete structures was established, considering the effects of temperature and loading on the chloride diffusion coefficient. Further, the reliability indexes of the reinforced concrete box girder, pier, and platform, located in the marine and land sections, in relation to service lives lasting various numbers of years, were calculated. The measured and calculated results show that the mean cover thicknesses of concrete piers in the marine and land sections are 52 mm and 36 mm, respectively, and the corresponding standard deviations are 5.21 mm and 3.18 mm, respectively. The mean compressive strengths of concrete in the marine and land sections are 56 MPa and 46 MPa, respectively. The corresponding standard deviations are 2.45 MPa and 2.67 MPa, respectively. The reliability indexes of the reinforced concrete box girder and platform in the marine section, under the condition of a service life of 100 years, are 1.81 and 1.76, respectively. When the corrosion-resistant reinforced bar was used in the pier structure in the marine section, its reliability index increased to 2.01. Furthermore, the reliability index of the reinforced concrete damaged by salt fog in the land section was 1.71. Full article