Journal of Bridge Engineering

In highway design, inverted-T bridge caps (ITBCs) have been extensively used in the United States. Depending on the project requirements, some ITBCs need to be skewed. In Texas, the traditional method of flaring the transverse reinforcement out is used to design the skewed ITBCs, as stated in the Texas Department of Transportation (TxDOT) Bridge Design Manual. However, this method has significant drawbacks in terms of design and construction. To solve the complexities of the traditional method, the skewed reinforcing method is proposed to TxDOT. In this paper, to enlarge the knowledge of the structural behavior and the economic impact of skew reinforcing in ITBCs, the nonlinear finite-element (FE) simulation and cost–benefit analysis of 96 full-scale skewed ITBC models are performed. The structural and economic performance of the specimens are investigated and compared according to the following design variables: (1) skew angle; (2) transverse reinforcement detailing; (3) amount of the transverse reinforcement; (4) presence of the end reinforcement; (5) size of the diagonal end reinforcement; and (6) the concrete strength. The finite-element analysis shows that skew reinforcing can achieve better structural performance than the traditional method in terms of stiffness, crack width, and the ultimate capacity. Moreover, the skew transverse reinforcement method considerably reduces the design and construction costs.

Prestressed with carbon fiber-reinforced polymer (CFRP) strands, a 42.2 m (138.3 ft) long single-span highway bridge superstructure was recently constructed to carry Interstate I-75 Highway over Sexton/Kilfoil Drain in Allen Park, MI. Experimental and analytical investigations were executed to overcome design challenges such as establishing the level of prestressing force, applicable strength reduction factors, and proper mode of failure to ensure an adequate performance under AASHTO LRFD service and strength limit states. After bridge construction, onboard sensors were used to verify its performance under traffic load and different environmental conditions. This manuscript provides details on an experimental investigation that was conducted to evaluate the constructability and possible failure modes in CFRP prestressed beams. In addition, the manuscript highlights key findings in the process of bridge design, construction, and field monitoring. To overcome the absence of yield phenomenon in CFRP and to establish visual warning before failure, beams prestressed with CFRP strands can be designed to achieve large deflection and extensive cracking patterns prior to failure. In addition, CFRP prestressed beam bridges, such as I-75 bridge, perform as analytically expected under service loads with a considerable load carrying capacity. Furthermore, and in the light of the multilevel strength reduction factors implemented in design, sufficient reserve capacity is embedded in the design to ensure adequate bridge resistance through its lifespan.

Barges offer a safe and cost-effective means for transporting commodities in inland waterway systems. This, however, comes with the risk of barge collision into bridge piers that span navigable waterways. While the vulnerability of such bridges has been investigated in an intact condition under vessel collision, the existing assessment methods fail to capture how scour events that bridge piers often experience during their service life can affect their response to vessel-induced impact loads. To address this gap, three bridge structures were modeled in this study, and a fully loaded barge traveling at 0.5, 1.0, 1.5, 2.0, and 2.5 m/s was allowed to collide into each of them after they underwent various scour scenarios. The scour scenarios under consideration were developed, following the procedure provided in Hydraulic Engineering Circular No. 18, for both 100- and 500-year floods. Based on the obtained results, the impact force, maximum shear, and maximum bending moment that the bridge piers experienced were found to decrease as the scour depth increased, mainly because the bridge piers gained flexibility. On the other hand, the maximum force that the bridge ends witnessed were determined to increase, indicating that the bridge structure can become vulnerable to failure at locations other than bridge piers as the scour depth increases. With an in-depth understanding of the magnitudes and trends of key structural response measures, the outcome of this study provided a rigorous multihazard perspective to improve the safety and performance of bridges built on navigable waterways.

Due to the maintenance and repair needs that commonly originate from expansion joints, link slabs are considered as a potential solution to move toward jointless bridges. The addition of partial-depth link slabs to existing bridges, however, can change the loading demand on not only superstructure components but also supporting piers. In particular, the consequences of adding link slabs to a bridge structure can vary, depending on support conditions underneath the individual link slabs. In the absence of any holistic study on this critical subject, the current study explored the effects of support conditions on strains and stresses developed in partial-depth link slabs through a full-scale laboratory investigation. For this purpose, various roller and pinned support conditions were tested and key response measures were recorded. The experimental tests were supplemented with finite-element simulations to further understand the effects of support conditions, taking into account various design details. The study was then extended to a representative bridge with the goal of evaluating how the addition of link slabs influences the loading demand that the bridge substructure experiences. Specifically, the effects of support conditions underneath the individual link slabs were modeled and evaluated. This provided original information about the change of loading demand that must be taken into consideration throughout the entire bridge structure when link slabs are considered to replace existing expansion joints.

This study investigates the concept that when localized bridge superstructure damage is present, the weights of passing vehicles inferred from a rotation-based bridge weigh-in-motion (B-WIM) system will deviate from those predicted by a strain-based B-WIM system. Rotation measurements were gathered from a 5.4-m simply supported laboratory model bridge crossed repeatedly by a four-axle model vehicle. Damage was incorporated by bolting stiffening plates onto localized sections of the test bridge. This “negative damage” concept, consisting of local increases in stiffness, allows several damage scenarios to be investigated on the test bridge. The experimental results show that when negative damage is present, rotation-calculated gross vehicle weights decrease, while strain-calculated gross vehicle weights remain unchanged. It is also shown that the approximate location of damage can be identified.

The objective of this paper is to propose the prediction method of the cross-sectional moment capacity for continuous steel box girder bridges based on the continuous strength method (CSM). First, the critical buckling strain of the compressed members in box girders is determined using the base curve in the CSM, with which the elastoplastic cross-sectional analysis is conducted to derive the ultimate bending moment of steel box girders under sagging and hogging bending states. Then, a large number of applicable cross sections of steel box girders are designed, and their cross-sectional moment capacities based on the CSM and the elastic and plastic analyzing methods are calculated. Based on an analysis of the mutual relationship of these three moment capacities, the linear and quadratic prediction equations are proposed for both the positive and the negative moment capacities of steel box cross sections. The proposed equations are adopted to predict the cross-sectional bending capacities of some steel box girders in experiments, and the predicting results agree well with the experimental ones. Lastly, the proposed equations are applied to predict the cross-sectional moment capacities of the main girder in Xiamen Second East Passage as a case study. Compared with their elastic moment capacities, the analysis results show that using the proposed linear prediction equations, the cross-sectional moment capacities presented a 5.2% increase for cross sections with a nominal width-to-thickness ratio of 39.2 at support and a 22.2% increase for cross sections with a nominal width-to-thickness ratio of 37.6 at midspan. The linear and quadratic interpolation equations can well predict the cross-sectional moment capacity of the steel box girder.

Long-span suspension bridge is a flexible structure. When subjected to a horizontal transverse live load, its deck undergoes significant transverse bending deformation, jeopardizing traffic safety. This paper proposes an analytical calculation method for the static response of the entire suspension bridge with a horizontal transverse distributed live load applied to its deck. First, each component’s geometric configuration and internal force for the suspension bridge subjected only to a dead load are obtained. Next, their values under the action of horizontal transverse live load are treated as basic unknown parameters. Then, governing equations are established based on geometric compatibility conditions, conservation of unstrained length, and force balance conditions. The unknown parameters are derived by nonlinear programming, estimating the entire suspension bridge’s displacements and internal force response. The proposed analytical calculation method only considers the structural state of the suspension bridge before and after the action of the live load but not the intermediate process. Therefore, the complex problem of geometric nonlinearity involved in the stress calculation of the suspension bridge is precluded, and the calculation results are more accurate. Furthermore, the conventional treatment of all hangers as a continuous thin film is avoided. Instead, the effects of the following factors are analyzed: tower bending in the bridge-axis direction, tower torsion, hanger elongation, hanger inclination, and rigid body displacement of the deck in the bridge-axis direction. Finally, the feasibility and effectiveness of the method are verified by finite-element method (FEM) analysis of a suspension bridge with a main span of 548 m.

This article presents an investigation of the structural behavior of a masonry arch bridge in Turkey. An analytical study has been conducted to provide the geometry of the structure, using laser scanning. A point cloud describing the geometry was obtained and properly transformed into a format that is appropriate for structural analysis software (CAE). Then, nonlinear finite-element models were developed to simulate structural responses of the bridge. The goal of the article is to highlight the influence of both continuum and discrete approaches and related constitutive laws on the responses of the bridge. Thus, continuum damage laws and a discrete model consisting of unilateral contact–friction interfaces were developed. Different load cases were tested and a comparison between the results obtained from the different approaches was considered. The failure mechanisms and the ultimate strengths were derived, and core points of the models were highlighted. The output of this work shows how the different failure models predict the behavior of the masonry arches. It also shows that the three-hinge mechanism, which has been depicted in classical studies for single-span arch masonry bridges under a horizontal settlement of supports, may also be obtained for multiarch bridges. Similarly, downward, vertical settlement of supports may result in the development of two hinges, as in single-span arches. Finally, the beneficial influence of the backfill in limiting the failure in the arch is addressed.

This paper presents a novel anchorage structure for stay cables to reduce the load on the concrete pylon. Called the staggered-supported steel anchor box (SS-SAB), this anchorage structure provides self-balancing of the horizontal component of the cable tension force during cable tensioning; the vertical load is transferred to the concrete pylon through a staggered support. The SS-SAB can tolerate the forces within the spatial cable plane and reduce the cracking risks of the concrete pylon. To investigate the behavior of the SS-SAB, a half-scale specimen was designed and tested. Data on the deformation, crack patterns, local strains, and slippages were obtained that demonstrate that the SS-SAB can delay crack occurrences in the concrete pylon. In a supplementary analysis, a finite-element analysis performed using the ABAQUS software suite delivered good accuracy. From the test and numerical analysis, the influence of the cable angle on load sharing within the concrete pylon was investigated. The effective scope of applications of the SS-SAB is provided.

With the appearance of large-span and heavy-duty high-speed railway suspension bridges, their deck deflections and deck-end rotation angles (DERA) under the live load became very topical indicators of bridge safety and stability. In contrast to multiple studies of the deck deflection, quite a few were devoted to the DERA. Based on the deflection theory, the continuous functions of deck deflection and DERA with the uniformly distributed load of any length acting at any position were introduced in this study. The method of finding the maximum value by derivative was performed to find the maximum DERA, maximum deck deflection, and its position. The proposed analytical algorithm was applied to a calculation example. The results were compared against those obtained by a trial-and-error method based on the finite-element method, which verified the feasibility and accuracy of the proposed analytical algorithm. Besides, the effects of several design parameters on the maximum DERA and maximum deflection of the deck, including dead load, span length, bending stiffness of the deck, and axial stiffness of the main cable were analyzed via the proposed method. It revealed that adjusting the main span length, dead load, and deck bending stiffness value was the most effective way to control the maximum deck deflection and maximum DERA.

Concrete bridges in extremely aggressive environments deteriorate mainly from corrosion of carbon steel prestressing strands and rebars. In prestressed concrete girders, corrosion might occur in the transverse reinforcement, which results in a decrease in shear resistance. Corrosion-free glass fiber reinforced polymer (GFRP) rebars and corrosion-resistant stainless steel rebars are promising solutions to address corrosion. However, GFRP rebars have lower ultimate strain, elastic modulus, and transverse shear capacity than stainless steel rebars. Two full-scale 12.8-m (42-ft) long AASHTO (American Association of State Highway and Transportation Officials) Type II girders with a deck slab on top of them were tested in shear at both ends. One girder was reinforced with duplex stainless steel Grade 520 (75) stirrups, and the other was reinforced with GFRP stirrups. Both girders had 11 carbon steel prestressing strands, each initially stressed to 75% of the strand’s ultimate stress. The girders were composite with a deck slab and had a smooth interface between the girder and slab. The objective was to experimentally assess the structural behavior of the girders. The girder reinforced with stainless steel stirrups failed in flexural shear while the girder reinforced with GFRP stirrups failed in interface shear due to the lower transverse shear capacity of GFRP rebars and smooth interface between the girder and slab. The experimental shear force at the failure of the girder reinforced with stainless steel stirrups was 9.1% greater than that reinforced with GFRP stirrups. Also, the direct replacement of stainless steel confinement reinforcement with GFRP resulted in strand slippage. It was found that the current AASHTO LRFD shear design provisions are conservative in predicting the vertical shear resistance of a girder reinforced with stainless steel stirrups or GFRP stirrups. The research findings will be helpful in the development of design guide specifications for prestressed concrete girders reinforced with GFRP stirrups.

There are many historical bridges around the world whose crucial information regarding their foundations is unknown. Such information is essential for an accurate safety assessment regarding scour hazard. Current methods for identification of bridge foundation characteristics are typically expensive, potentially disruptive, and limited in their applications. Thus, the numerical feasibility study described in this paper assessed whether a nondestructive geophysical technique such as electrical resistivity tomography (ERT) could be used for this purpose. Synthetic scenarios were created accounting for different combinations of material resistivity. Two standard measurement sequences (dipole–dipole and Schlumberger) and an optimized one (“Compare R” method) were tested. Results showed that the depth of the bridge foundation was roughly well represented in all cases. However, the optimized sequence revealed slightly better results. Although this small improvement observed did not significantly affect the results of the simplified scenarios assessed by this study, it could be decisive for more complex scenarios. These findings demonstrated that ERT can be used to identify the depth of bridge foundations in an inexpensive, rapid, and nonintrusive way, allowing for more accurate assessment of bridge safety and scour risk ratings.