Journal of Bridge Engineering

Interstate 80 (I-80) through Wyoming carries a large volume of cross-continental trucks and large energy-industry trucks compared to many other states. Moreover, frequent weather closures position trucks side-by-side and end-to-end for miles so that they travel as a convoy once the road opens. The unique truck traffic and traffic patterns of Wyoming potentially create larger demands on bridges than were considered in the development of the national design specifications, and these differences may hold true for other states with unique traffic situations. This study was performed to assess bridge safety (in terms of national design expectations) along the I-80 corridor. Rational load cases for situations of single vehicles and multipresence were developed to model the traffic pattern characteristics thought to exist on I-80 across Wyoming. The 75-year design-life live-load model was applied for reliability studies. Reliability indexes were produced through Monte Carlo simulation. The results indicated that truck traffic and traffic patterns in Wyoming create larger demands than considered in the national specifications. Short multispan bridges were found especially critical. To maintain target-bridge safety, two recommendations were made: (1) specifications should incorporate the published commentary about low-boy tandem load as part of the loading specifications and (2) the state DOT (and that of other states with similar truck-traffic conditions) should increase the live-load factor, γ_L, for interstate bridges. Recommendations for the live-load factor are presented.

In this paper, a new real-time damage identification method has been presented for bridge structural health monitoring (SHM) considering temperature variation. The method utilizes model-based damage identification that involves three major steps: (1) efficient basis functions—extracted from finite-element (FE) models prior to real-time identification; (2) partial least-squares regression (PLSR) analyses; and (3) the fusion of different types of structural responses into damage indicator. By treating local damages as equivalent vertical loads and then cross-referencing global (inclinations) and local (strain) data, the hidden damage information in bridge structures can be detected and localized in a timely fashion, even in the presence of unknown temperature variation as well as vehicle loads. Inclinations alone cannot reflect local damages, but by fusing inclinations and strains (that represent local damage) into the proposed damage indicator, local damages can be identified. Numerical simulations on a medium-span continuous bridge demonstrate that the proposed method is insensitive to measurement noise and some common modeling errors, revealing the potential of real-time damage identification in bridge SHM applications.

Tower–girder transverse pounding was observed on the Yokohama Bay Bridge wind tongue during the 2011 Great East Japan Earthquake. Damage to the wind tongue due to pounding can potentially lead to damage of other members. However, pounding was not taken into consideration in the design, and the process of how the damage occurs after the wind tongue damage has not been clarified. Therefore, a way to model the damage process involving tower–girder transverse pounding is needed. In this study, a frame model of the Yokohama Bay Bridge was constructed to reproduce the observed damage that occurred as a result of the pounding. A multiscale model was then constructed by combining the global frame model with a local finite-element model consisting of a shell and solid elements. The model was validated through comparison with actual measurements. Dynamic analysis of the multiscale model clarified the deformation of the wind tongue during large earthquakes and the resulting damage to the bridge. The model demonstrated that ductile damage can occur at the base of the wind tongue during a Level 2 earthquake and that the tower link can then drop off due to its large displacement after the wind tongue damage.

The hangers on long-span suspension bridges are significantly prone to wind-induced vibrations due to their light mass, low frequency, and small structural damping. These vibrations are known to cause fatigue problems and impair the serviceability and safety of structures. The possibility of wake-induced vibration of the hangers is theoretically studied in this paper. First, a series of wind tunnel tests for two smooth circular cylinders were carried out to identify the eight aerodynamic derivatives of the leeward cylinder. Second, the motion equations of the leeward cable were established on the base of the unsteady and quasi-steady theories by using the data measured from the wind tunnel tests. These equations are numerically solved by adopting the Runge-Kutta method. Finally, a series of numerical simulations based on the structural parameters of a hanger on the Xihoumen Bridge were conducted to study the mechanism of the wake-induced vibration of the leeward cable of the hanger. The results show that obvious oscillations of the leeward cable take place in the spatial region of 5.2 ≤ X ≤ 5.6 and 1.1 ≤Y ≤ 2.1, and the vibration frequency of cable is slightly smaller than its natural frequency. A positive work within a period is always done by the aerodynamic stiffness force if large-amplitude vibration of wake-induced vibration takes place. It appears that the aerodynamic stiffness force is the key factor to evoke the wake-induced vibration of the leeward cable. This agrees well with the feature of the wake-galloping vibration observed from the power transmission lines. Moreover, it seems that the quasi-steady theoretical model could reflect the main characteristics of wake-induced vibration just as the unsteady theoretical model. However, the oscillation amplitude obtained from the quasi-steady theoretical model is slightly smaller than that from the unsteady theoretical model.

The early fatigue cracking of orthotropic steel decks has been a long-standing problem for heavy traffic regions of China’s long-span bridges. However, the actual fatigue life is much lower than the fatigue life calculated by fatigue design codes. In this study, a modified full range S-N curve, the M-S-N method, is proposed to evaluate welded joint fatigue life, considering mean stress, which is based on metal fatigue theory. As an example, a combined shell-solid finite-element model of a segmental bridge is first built for the Jiangyin Bridge to obtain the real stress, integrating welding residual stress and vehicle load stress. The fatigue life is then calculated and compared in order to consider the influence of different vehicle loads and deck-plate thicknesses. The calculation results show that the fatigue life of the deck-rib welded joint in the Jiangyin Yangtze River Bridge decreases nonlinear at a staggering rate with the increase in vehicle load. Under the condition of severe overload heavy vehicles, the Jiangyin Bridge fatigue life is only 2.17 years according to the M-S-N method, which matches practical situations. Deck-rib fatigue life obviously increases with the increase in deck thickness. The current steel bridge deck design with a 16-mm-thick plate is not safe under heavy traffic conditions.

Recently, there has been a rapid increase in using ultrahigh-performance concrete (UHPC) in bridge connections due to its high compressive strength, pre- and postcracking tensile strengths, superior bond, and durability characteristics. However, the behavior of field-cast UHPC connections under temperature effects is not yet fully understood. Furthermore, the temperature distribution that produces the largest thermally induced stresses in UHPC connections is unknown. In this study, the thermally induced stresses in field-cast UHPC shear key connections in an adjacent precast prestressed concrete box beam bridge were investigated using field data as well as a three-dimensional finite-element (FE) model. The FE model was validated using field data and exhibited the ability to capture the behavior of the bridge. A new temperature distribution was noticed based on the data analysis. This temperature distribution has not yet been considered by professional bridge design specifications, although it produced the largest thermally induced stresses in UHPC connections and at the beam–key interface. The observed temperature distribution should be considered in the design of UHPC shear keys for these types of bridges.

This article presents an experimental investigation of a free-standing single-column bridge tower with chamfered square cross sections in smooth flow, with a particular focus on its aerodynamic characterization. First, a sectional model test with a scale ratio of 1:30 was conducted to determine the static force coefficients and across-wind aerodynamic damping features. In addition, a 1:80 scaled full aeroelastic model was employed to estimate its aeroelastic response characteristics. The experimental results reveal the occurrence of interactions between three-dimensional third-mode vortex-induced vibration (VIV) and first-mode galloping, which have rarely been reported in early documentation. However, the understanding in terms of the mechanism of such VIV–galloping interaction is still insufficient. Moreover, two types of aerodynamic stability countermeasures, namely, curved guide vanes and vertical fins, were proposed, and their effects on structural aerodynamic stability were examined. In general, it was found that the installation of curved guide vanes is more advantageous in terms of improving the aerodynamic stability of the structure.

Stirrups in RC beams are more vulnerable to corrosion than longitudinal steel bars due to the thinner concrete cover, and the shear behavior may deteriorate faster than the flexural behavior under fatigue loading. An experimental study was conducted to investigate the deterioration mechanism of the shear fatigue behavior of RC beams with corroded stirrups. RC beams were corroded by an impressed current before fatigue loading was applied. The fatigue test results showed that all beams failed with fatigue fracturing of the stirrup, and the corrosion of stirrups had a significant influence on the shear fatigue behavior and fatigue life of RC beams. It was observed that fatigue cracks initiated and propagated rapidly around corrosion pits, and the stirrup fractured at the minimum cross section where the corrosion pits had formed. The strains in the stirrups, longitudinal steel bars, and concrete increased with an increase in the number of loading cycles, and a significant increase of the midspan deflection was observed in all beams. With the increasing corrosion degree of stirrups and load amplitude, the stress amplitude of the stirrups increased obviously, especially at the minimum cross section, and the stress concentration at the corrosion pits put the stirrups in a more adverse situation, resulting in faster deterioration of the shear fatigue behavior and a decrease in the fatigue life of RC beams with corroded stirrups.

This study explored an optimal intensity measure for probabilistic seismic demand models of multiple components in cable-stayed bridges subjected to pulse-like ground motions. To achieve this goal, this study selected a cable-stayed bridge as a case study. Due to the limited number of recorded motions, artificial pulse-like motions were generated using an existing simulation method to obtain a reliable estimate of probability seismic demand models. For the subject bridge, seismic demand analyses were undertaken under a combined set of recorded (a total of 121 pairs) and artificial (a total of 121 pairs) ground motions. In total, seven structure-independent intensity measures and six types of engineering demand parameters representing maximum component responses were considered in this study. Peak ground acceleration (PGA) tended to be appropriate for the short-period components (i.e., pier and upper side of pylons), whereas peak ground velocity was found to be the optimal intensity measure for long-period components (i.e., lower side of pylons, cables, and displacement-related seismic demands). The lower side of pylons is more vulnerable than their upper side, and on the basis of efficiency, practicality, proficiency, sufficiency, and hazard computability, peak ground velocity appears to be the best intensity measure of the cable-stayed bridge subjected to pulse-like ground motions. However, PGA can be chosen as the ideal intensity measure for the piers.

This paper presents an experimental study of the seismic behavior of RC square columns strengthened with self-compacting concrete-filled carbon-fiber-reinforced polymer (CFRP)-steel tubes (CFCSTs). Eleven columns were tested under lateral cyclic load while simultaneously being subjected to constant axial load. The test parameters included the number of CFRP layers, the thickness of the steel tube, and the axial load level. The entire failure process, ultimate lateral load, and deformation capacity were analyzed. The experimental results indicated that the seismic bearing capacity of the RC columns could be improved significantly while the strengthening method was applied, because the ultimate lateral loads of the strengthened columns were 7.36–9.67 times that of the unstrengthened column, and the improvement ratio of ductility parameter reached 42.38–115.56%. The CFRP jacket could effectively delay or even prevent the local buckling of the steel tube, leading to better structural seismic performance. As the number of CFRP layers increased, the ultimate bearing capacity, ductility, and energy-dissipation capacity of the CFCST-strengthened columns increased slightly. The CFCST-strengthened columns under a higher axial load level exhibited better ultimate bearing capacity and energy-dissipation capacity but worse ductility. With the increase of the thickness of the steel tube, all seismic performance indexes significantly improved. The CFCST-strengthened columns were simulated by using the finite-element analysis software Abaqus 6.14–4. The comparison of the analytical results with the experimental results revealed that they are basically consistent with each other.

Serviceability deflections and strains at the crown, support, and quarter point of two aged masonry arch bridges under operating passenger and freight trains were assessed using a digital image correlation method. Three lasers recorded the passage of the wheels; these data were used to ascertain the wheel positions, which corresponded well with the peaks of the deflections measured. The measured maximum deflection and strain were 0.5 mm and 110 microstrain, respectively; these data were validated through a three-dimensional (3D) finite-element model incorporating saturated soil fill, masonry arch, and their interface. The predicted strains matched well with the field measurements. The variation of the strains with the wheel positions over the arch barrel was also simulated. The magnitudes of the deflection and strain were too small to cause serviceability limit-state exceedance alarms for the masonry arches.

The sunflower arch bridge is a new type of reinforced concrete arch bridge that has been developed recently. Because of the complex constructional details, the stress distribution at the joint between the main arch and spandrel arch is very complicated. To explore the mechanical behavior of this new type of arch bridge, particularly the stress state at the joint of the arch, a 1:5-scaled model of a segment for a sunflower arch bridge was tested. The displacements and stresses at key locations of the tested model were recorded. The experimental results showed that the displacements of the main arch and spandrel arch under dead loads were notably small, which indicated that the global stiffness of the arch was sufficiently large. Moreover, the maximum tensile stress at the end of the spandrel arch subjected to dead loads was larger than the tensile strength of the concrete; therefore, the concrete in these regions is vulnerable to cracking. To avoid cracks at the end of the spandrel arch, an optimized design scheme was proposed for the joint using a steel I-beam to replace the concrete at the end of the spandrel arch. Design parameters were also suggested through a comprehensive parametric investigation based on finite-element analysis (FEA).

Hydrodynamic effects are concerns in the seismic analysis of bridges with complex hollow piers submerged in a reservoir. In this study, potential-based fluid elements were employed to set up a three-dimensional numerical fluid–structure interaction model to account for the hydrodynamic effects of interest. A typical reservoir bridge with a nonuniform hollow pier was taken as an example structure. Linear and nonlinear dynamic analyses were carried out to investigate the seismic responses of the example pier under six near-fault and six far-field earthquake records. The accuracy of the added-mass model was validated in the linear and nonlinear domains. It can be concluded from the case studies that (1) the effect of surface gravity waves is not significant; (2) the inner water increases the seismic responses of the hollow pier; (3) structural nonlinearity cannot be neglected in seismic analyses of piers subjected to strong earthquakes, especially for near-fault earthquakes; and (4) the added-mass model is an efficient alternative method for both linear and nonlinear seismic analyses, regardless of water depth, earthquake characteristics (e.g., near-fault or far-field), and intensity.