Journal of Bridge Engineering

This paper investigates the performance of curved soffit reinforced concrete beams strengthened in flexure with carbon fiber reinforced polymers (CFRPs) under static loading. The effect of concavity on the effectiveness of flexural strengthening is explored using both pultruded CFRP laminates and wet layup CFRP sheets in terms of the degree of flexural strengthening, CFRP strain level prior to debonding, cracking resistance, and ductility. In the experimental program, eight simply-supported beams were tested under displacement-controlled static loading, including three beams strengthened with CFRP sheets, three beams strengthened with CFRP laminates, one unstrengthened beam with flat soffit and one unstrengthened beam with curved soffit. The concrete beams were 2.7 m long and had mid-span cross sections of 140 × 260 mm. The degree of curvature used in this study was 20 mm per 1 m. Owing to strengthening, the nominal flexural strengths of the beams were increased by up to 37% and the service load deflections were reduced by up to 14%. A curvature of 20 mm per meter was observed to reduce the FRP's maximum strain at the time of debonding by 31%–33%.

Many bridges in the United States are classified as structurally deficient and many others are nearing the end of their design service life, necessitating robust and durable bridge rehabilitation methodologies. States’ department of transport have recently developed innovative solutions for accelerated bridge construction using Ultrahigh Performance Concrete (UHPC) as grout material between prefabricated bridge components or as an overlay over existing bridge decks to increase their service life. The normal strength concrete (NSC)-UHPC interface behavior is critical in determining the overall performance of such NSC-UHPC composites. In this study, an experimental investigation was performed to quantify the effect of surface preparation and interface reinforcement on NSC-UHPC interface performance. The results from this study were compared with the current design guidelines for estimating interface shear capacity. In general, it can be concluded that increasing roughness depth and reinforcement area has a positive effect in interface shear capacity.

The flexural behavior of steel-ultrahigh performance concrete (UHPC) composite beams with waffle slabs (SUCBWS) was investigated through experiments. The effects of design parameters, including the ratio of rib height to upper panel thickness, ratio of width to spacing for longitudinal rib, ratio of transverse rib spacing to longitudinal rib spacing, waffle-slab height, and the arrangement of studs, were evaluated by six specimens. The crack propagation of UHPC, failure mode, load-deflection relationship, strain distribution of main cross sections, and relative slip between the steel beam and the waffle slab were analyzed. The results showed that SUCBWS was characterized by obvious bending failure and good ductility. The composite beam achieved its flexural strength without obvious longitudinal splitting cracks on the waffle slab, even for the transverse reinforcement ratio of 0.33%. As the ratio of width to spacing for longitudinal rib and the ratio of transverse rib spacing to longitudinal rib spacing increased, the stiffness and integrity of waffle slab was weakened. Finally, the transformed section method was developed to calculate the elastic flexural capacity of SUCBWS.

Public transportation is vulnerable to terrorist attacks due to its accessibility, especially bridges in the highway and urban systems under blast loading. Prefabricated segmental reinforced concrete (PSRC) piers are one of the popular constructional elements in accelerated bridge construction projects in recent years. Therefore, it is necessary to investigate the dynamic response and damage mechanism of the PSRC pier under close-in blast loading. In this paper, a blast experiment on one conventional square reinforced concrete (RC) pier and one square PSRC pier was conducted in a bottom explosion experiment. Based on the test results, the numerical models were developed and calibrated according to the theoretical prestressing force, experimental displacement history, residual displacement, and failure height. The validated model could be used to reliably and accurately analyze the blast response and the damage mechanism of PSRC piers. Results showed that the PSRC pier had a localized segmental failure in the bottom explosion zone and other segments had vertical cracks and concrete extrusion above the explosion zone resulting from the concrete squeezing stress, and the segmental interface could block the stress flow propagation; the monolithic pier had massive transversal cracks on the upper parts due to the vertical propagation of stress flow; the PSRC pier had small relative segmental slips and rotations with a restored movement due to the restraint of prestressing force under a scaled distance of 0.6 m/kg^1/3, while it had large localized slips with irreversible displacements without any restraint of prestressing force under a scaled distance of 0.4 m/kg^1/3; the PSRC pier preferentially experienced localized segmental shear failure under surface blast, while it had an overall flexural failure under air burst; and the explosive energy of the PSRC pier was mainly dissipated by the deformation and spalling of concrete.

Integral abutment bridges (IABs) have become popular with departments of transportation throughout the United States due to their lower maintenance and construction costs and longer service life. Nevertheless, IAB design and construction vary widely across the country, and not all aspects of IAB behavior are fully understood. Research has previously been conducted on IABs, but primarily with a focus on substructure behavior. However, recent studies have shown that IAB superstructures may develop significant stresses, which warrant consideration in their design. The work reported herein addresses the need to better understand not only IAB substructure behavior but also superstructure behavior, with a goal of improving design and construction provisions for IABs. Two bridges were instrumented, with primary focus on superstructure behavior and more limited instrumentation of the substructure. Corresponding finite-element models were developed based on modeling techniques and findings from prior parametric studies. It was found that the IAB decks and girders (in the superstructure) and abutments and piles (in the substructure) generally show seasonal and even daily trends with respect to changes in temperature, with the exception of bottom-flange girder stresses that have wider variability not directly related to temperature change. Prior modeling assumptions regarding the rigidity of various IAB connections were also validated through the field monitoring data.

A composite bridge deck system with steel fiber-reinforced concrete (SFRC) is an effective solution to the fatigue cracking problem of steel orthotropic decks. The governing fatigue failure modes were investigated by experiment and numerical simulation in determining the fatigue failure criteria and fatigue strength of steel–SFRC composite deck. Wheel running tests of a large-scale composite orthotropic deck were referred to obtain the fatigue stress and observe the failure mode sequence. A three-dimensional numerical model was then established and verified for the composite deck to attain the unfavorable fatigue stress range for each fatigue criterion under varying variables regarding SFRC overlay, steel deck, and headed studs. The parametric studies showed that the SFRC overlay cracking primarily governs the fatigue strength, and the thickness and flexural strength of SFRC overlay are crucial parameters. The SFRC with high flexural strength of at least 10 MPa is recommended to apply in the thin overlay with less than 100 mm thickness, and the common SFRC can be used with the overlay thickness of at least 120 mm for the orthotropic steel deck configuration in the common range of the design parameters.

Coastal bridges are continually attacked by chloride ions during their lifetime, making the structures vulnerable. Piers, which are the main components of bridge structures to resist lateral forces, are supposed to have adequate deformation capacity to protect the structures from collapse. This paper studies the performance of coastal bridge piers that deteriorate nonuniformly along the height due to varying corrosion characteristics. A prediction method is proposed to estimate the ultimate lateral displacement of coastal bridge piers, and the results of cyclic tests are used to verify the prediction accuracy. Next, the failure mechanism of coastal bridge piers is investigated, taking into account the combined influence of corrosion level and varying performance deteriorations along the height. The analytical results indicate that the sections along the pier height behave differently due to varying corrosion levels when the service time increases, and the maximum damaged position may transfer from the pier bottom to the zone where the performance deteriorates most significantly. In addition, the length proportions between different zones along the pier height strongly affect the seismic failure of coastal bridge piers.

Many states have problems with transverse cracking of the concrete bridge decks. These cracks occur in negative and positive moment regions and can affect the serviceability of the decks. To improve the deck durability, internally cured concrete (ICC) has been recommended. However, limited research has been conducted to evaluate the field performance of ICC bridge decks. This paper evaluates the field behavior of an ICC deck in comparison with an adjacent conventional concrete (CC) deck exposed to thermal variations. Each deck was instrumented to monitor its behavior under environmental conditions and then compared with its performance under live loading. The results indicated that temperature fluctuations had a significant influence on the potential for deck cracking. It was observed that the ICC deck had a significantly lower cracking potential when compared with the CC deck after four months of construction. In addition, the results showed that the tensile stresses in the reinforcement of the ICC deck due to thermal variation was only 5% of the maximum allowable stresses, whereas it was only 70% of the maximum allowable stresses for the CC deck. Moreover, it was observed that both decks exhibited similar performance under the live load testing.

In this study, a new transverse post-tensioning (TPT) technique for box girder bridges is investigated, where TPT is applied at the top flange of the girder resulting in eliminating the intermediate transverse diaphragms. A one-third-scale bridge model consisting of four adjacent box girders with partial-depth shear keys was erected and tested. The bridge model was investigated for the optimal TPT force and spacing to ensure a uniform distribution of the clamping prestress. The efficiency of the proposed technique in transversely distributing live loads during simulated service and ultimate conditions was also investigated. Test results demonstrated that distributing the TPT force at a shorter spacing along the length of the bridge is more efficient than increasing the TPT force at discrete distant locations in producing the minimum required concrete prestress. It was observed that the effect of TPT force and spacing was insignificant during the simulated service condition, where shear keys remained intact or partially cracked. However, at failure, the presence of TPT added redundancy to the bridge model and mitigated any sudden failure when shear keys were fully cracked.

To provide benefit for design, rating, evaluation and management of signature bridges, site-specific extreme wind speeds, structural temperatures, and traffic load effects of a long-span cable-stayed bridge were estimated using relatively long-term structural health monitoring (SHM) data and compared with respective design values in this paper. The generalized Pareto distribution was adopted and briefly introduced to predict the extreme values in consideration of its advantage in making full use of limited measurement data available. The configuration and characteristics of the 3rd Nanjing Yangtze River Bridge and its SHM system were then presented. The extreme wind speed at the deck level and the four extreme temperatures of the bridge were estimated and compared with the corresponding design values. After a brief introduction to the simulation of traffic load effects, five extreme traffic load effects were finally estimated and compared with the design ones. The comparative results showed that the site-specific extreme wind speed, uniform girder temperature change, and five traffic load effects are all lower than the respective design values. The site-specific extreme vertical and transverse girder temperature differences and the site-specific extreme tower temperature difference were, however, larger than the respective design values.

Bridge decks were constructed in Minnesota from 1973 to 1989 with mixed reinforcement, meaning a top mat of epoxy-coated reinforcement and a bottom mat of uncoated reinforcement, to reduce corrosion. This paper investigated how the deterioration of concrete decks built with mixed reinforcement compared to control structures containing all epoxy-coated reinforcement using rating data from inspection reports. The results were subdivided to indicate how the superstructure type, average daily traffic, route type, wearing surface crack density, and skew affected the condition ratings and deterioration. The mixed reinforcement decks reached worse condition states than the control structures considering the underside of the deck. Mixed reinforcement decks transitioned to the condition state where rehabilitation is often initiated after remaining in the prior condition state for 8.5 years. Bridges with a steel superstructure reached worse condition state ratings. Average daily traffic, route type, wearing surface crack density, and skew did not have consistent behavior considering deck ratings and deterioration.