Journal of Bridge Engineering

This paper presents experimental and numerical investigations of the shear strength of synthetic fiber-reinforced concrete (SYN-FRC) box culverts designed for fill height of 610 mm (2 ft) or less and subjected to the American Association of State Highway and Transportation Officials (AASHTO) HL-93 wheel load. Shear and flexure material tests associated with numerical analysis were conducted to obtain the material properties of concrete with compressive strength of 34 MPa (5,000 psi) and synthetic volume fraction of 0.52%. The material tests showed that the shear and flexure strength of SYN-FRC were greater than those of plain concrete (without adding fiber). The flexure material test showed that SYN-FRC can carry load even after concrete cracking, unlike the plain concrete, which collapses immediately after cracking. In addition, four full-scale SYN-FRC box culverts were tested in the laboratory, and numerical models were calibrated, using experimental data. The load was applied through a rigid steel plate at distance d from the tip of the haunch to satisfy the AASHTO HL-93 wheel load requirements. The selected load location was a critical section for the shear and imposed shear failure mode. A comparison of box culverts with and without synthetic fibers revealed that adding a synthetic fiber volume fraction of 0.52% increased the shear capacity and the ductility. All specimens failed in the shear failure mode associated with an inclined shear crack from the tip of the haunch to the middle of the loading plate. The results demonstrated that synthetic fibers can be a viable alternative to shear transverse reinforcements. Additionally, numerical verification of SYN-FRC box culverts validates the use of a concrete, brittle, cracking material model for simulating SYN-FRC in the finite-element method (FEM).

This study presents a practical approach for the design of horizontally curved steel I-shaped bridge girders with tubes as flanges [i.e., tubular flange girders (TFGs)]. Previous research has shown that the large torsional stiffness of a TFG, compared with a conventional steel I-shaped plate girder (IG), leads to improved behavior and potential for simpler curved bridge erection. The study shows that existing design criteria for curved IGs in the current design specifications can be adopted for curved TFG design. A few modifications to the existing design criteria, developed for TFGs, are presented. Simplified finite-element (FE) models for use in the design of curved TFG bridges are summarized. The simplified FE models are used to determine the design load effects for various limit states, and these limit states are then checked using the design criteria. Detailed FE models are also summarized, and these models are used to evaluate the limit state responses of several curved TFG bridges designed using the approach presented in the study. The results show that the design criteria used for curved IGs, with a few modifications, can be used to safely design curved TFGs for highway bridges. Additionally, the behavior of curved TFG bridges with different types of TFGs are compared.

Ultrahigh performance concrete (UHPC) is an advanced cementitious material which has excellent mechanical and durability properties, making it appropriate for the rehabilitation of concrete structures. This paper investigates the usage of a thin layer of UHPC overlaying a normal strength concrete (NC) deck. The behavior of the interface connection will have a significant impact on the overall structural and durability performance of the UHPC-NC composite deck system. An integrated experimental and analytical study was conducted to understand the influence of several variables, such as normal concrete strength, interface roughness, and curing condition on the shear transfer behavior across the interface between UHPC and NC. The laboratory testing was performed in two phases, including slant shear testing in Phase-I and flexural testing of composite deck specimens in Phase-II. A total of sixty test units with five different surface textures and three different concrete strengths were loaded to failure in Phase-I. Four 197 mm (7.75 in.) thick, 0.61 m (2 ft) wide, and 2.74 m (9 ft) long deck specimens with 38 mm (1.5 in.) thick UHPC overlay and different interface texture were tested to failure in Phase-II. The slant shear test results demonstrated that the shear transfer across the interface is adequate for overlay applications for all textures with roughness equal or more than 3 mm (0.12 in.) regardless of concrete strength, which was later confirmed by the composite deck specimen tests. The interface bond strength was not affected by curing conditions (heat treatment or ambient) used for UHPC. Current bridge design guidelines provide a conservative estimate for the UHPC-NC interface shear strength.

Computational simulation was used to investigate the collision process between medium-weight, single-unit trucks and reinforced concrete bridge piers. The simulation results were used to formulate and calibrate a pulse model to describe, in a simplified manner, the dynamic force demands imposed on a bridge pier by a colliding truck. Key parameters in the force demand model were impact speed, truck weight, and pier dimensions. Accuracy of the proposed demand model was assessed by comparing the damage modes and displacement profiles of piers subjected to impact by the computational truck model and an equivalent, simplified pulse model. Extensive numerical simulations were carried out using the developed pulse model to identify prominent failure mechanisms. Damage levels were quantified through the use of macrolevel deformation parameters, such as plastic rotation and shear distortion. It was shown that shear damage can be substantially reduced by using capacity design theory to proportion the piers.

Precast concrete segmental (PCS) box girders are popular in bridge construction, although structural deterioration due to creep and shrinkage has been a concern. In contrast to the extensive studies on shear and bending behaviors of PCS beams, investigation on the long-term performance of PCS box girders is limited. In this study, six PCS box girders with dry joints were loaded inside a laboratory for 1 year, and ambient temperature, relative humidity, prestress loss, concrete strains, and time-variant deflections were monitored to investigate the long-term performance of PCS box girders under multiple factors. Numerical simulation was performed, where the variation of ambient factors was taken into account, and a good match between simulated and test results was observed. Based on laboratory observations and numerical simulation, it was found that shorter concrete age at loading, lower concrete strength, fewer segments, smaller reinforcement ratio, more shear keys, higher initial prestress, and larger external load resulted in more significant structural deterioration, including the loss of prestress and increasing deflection. According to the numerical simulation, the loss of prestress along the girder was complex and influenced by the change in cross section, location of shear keys, and tendon shape.

Precast prestressed double-tee girder bridges are common on county bridges in South Dakota. However, the longitudinal joints of these bridges are rapidly deteriorating, causing girder replacement after only 45 years of service. The present study was conducted to develop, construct, and evaluate rehabilitation methods for the longitudinal joint of double-tee bridges. Twenty joint rehabilitation detailing alternatives are proposed and ranked in the present study. Thirteen large-scale beams were tested to investigate the performance of the best four rehabilitation details. Ultrahigh-performance concrete (UHPC) and latex modified concrete (LMC) were selected as the filler materials. Subsequently, two joint concepts, “pocket” and “continuous,” were developed based on the experimental and analytical studies. A full-scale 12.19-m (40-ft) long double-tee girder bridge was constructed using conventional longitudinal joint detailing and was tested under fatigue loads. Subsequently, the bridge was rehabilitated using the two proposed details and was tested under fatigue and strength loading. No significant damage, beyond initial shrinkage cracks in LMC, was observed throughout the fatigue testing. Furthermore, the stiffness of the bridge did not degrade. No significant damage or yielding of the reinforcement in the rehabilitated joints was observed throughout the strength testing. Overall, the rehabilitated bridge met all current code requirements indicating sufficient structural performance. The rehabilitation cost of a double-tee bridge with pocket detailing is expected to be less than 30% of the bridge superstructure replacement cost.

Slide-in bridge construction (SIBC) has been used in accelerated bridge construction (ABC) for the last decade. Slide-in bridge construction is carried out using bearing pads consisting of polytetrafluoroethylene (PTFE) and steel sliding surfaces. In this study, coefficient of friction (COF) measurements were made with variable surface roughness, lubrication type, sliding speed, and contact pressure. Among three tested surfaces, the rough rolled stainless steel and the carbon steel produced COF values much higher than those of stainless steel with a #2B surface. Unlubricated and graphite-lubricated surfaces resulted in very high friction values, whereas the values for soap, grease, and oil were comparably lower. The oil and grease tests gave the lowest friction values, 0.90–4.04% and 0.67–5.15%, for the studied contact pressures, respectively, and are recommended for future use. Higher contact pressures typically resulted in lower COF values. Overall, the currently recommended COF values underpredict the COF compared with the results from this study. However, for higher contact pressures, this study found lower COF (e.g., for high pressure of 55 MPa, 2% versus 0.9–1.44%) compared with current recommendations and the opposite for low contact pressures (e.g., for 11 MPa, 2.71% versus 4.04–5.66%). Unlubricated sliding surfaces are not recommended due to the large scatter in comparable data in this study and the literature.

Precast concrete bridges have many advantages over cast-in-place construction. Prefabrication typically requires less time at the site due to the ease of installation. Furthermore, production in a controlled environment can result in higher bridge quality. However, the quality of field connections is a key challenge in ensuring the integrity of the bridge seismic performance. A Federal Highway Administration (FHWA) research project conducted at the University at Buffalo in 2012 using ultrahigh-performance concrete (UHPC) to evaluate the suitability of deck-level connections between precast prestressed concrete bridge girders is reported in this paper. The structural performance of the UHPC connections has been investigated by both cyclic and static loading tests at the FHWA Turner–Fairbank Highway Research Center. This paper discusses the results of a shake table study on the seismic performance of two full-scale prestressed girders connected with UHPC. The main objective of this experimental study was to observe the seismic performances of the UHPC connection between two bridge girders to assess the applicability of using UHPC-connected precast bridge girders in moderate to high earthquake regions. The experimental results show that the use of a UHPC connection with straight rebar protruding from the prestressed girders provided adequate resilience even under high-level earthquake ground motions.

We present an innovative prefabricated composite box girder with corrugated webs and concrete-filled steel tube slab to prevent cracking in the web and reduce the self-weight, which is suitable for long-span structures. We carried out systematic experimental and analytical studies to investigate the structural performance, including the loading capacity and dynamic properties of a prefabricated composite box girder bridge before and after erection. Firstly, we tested a prefabricated composite girder with a single box section before erection under monotonic loading, measuring vertical deformation, flexural strain on the slabs, and shear strain on the corrugated steel webs, and evaluating the load-carrying capacity and stiffness reduction. Secondly, we conducted field live-load tests, including a calibration test and a dynamic test, on a composite bridge with twin prefabricated box girders. We hired four-axle heavy trucks for a calibration test to explore the static responses in terms of displacement, bending strain on the slabs, and shear strain on the corrugated steel webs. In the dynamic tests, we carried out a modal test using ambient vibration method and a moving load test in order to determine the dynamic behavior, which involves natural frequencies, the mode shapes, and the dynamic load factor (DLF). Based on the test results, the structural performance was evaluated by the AASHTO bridge rating process. All the findings from the load-carrying capacity test at ultimate state, calibration and dynamic load tests at service state in this study may provide a reference for the design and construction of such type of bridges.

This paper discusses the efficacy of different fiber-reinforced polymer (FRP) techniques on the behavior of RC columns under uniaxial high eccentric compression. Eight RC columns were strengthened using three FRP strengthening schemes: (1) near surface mounting (NSM), (2) external bonding (EB), and (3) hybrid strengthening, which uses a combination of NSM and EB. All the columns were tested under an eccentricity (e) to column depth (h) ratio of 0.63. The results obtained from the experiments were compared with the results of numerical analysis using the finite-element (FE) software developed at the University of Stuttgart. The hybrid FRP-strengthened specimens showed better performance compared with only NSM or EB in enhancing the peak strength and ductility by 51% and 277%, respectively, when compared with the control RC columns. Moreover, the brittle bond failure typically observed in NSM-strengthened columns was effectively prevented through FRP confinement in hybrid strengthening. The FE modeling approach developed in this work effectively captured the overall behavior of RC columns under eccentric compression. An extensive parametric analysis using the validated modeling approach was performed to quantify the effectiveness of the different strengthening techniques for a wider range of design parameters.

The South Dakota Department of Transportation (SDDOT) allows the use of precast, prestressed double-tee girder bridges in county and local roads because they are economical and fast in construction. However, many of double-tee bridges are deteriorating, and some need total replacement after 40 years of service. Furthermore, there is only one supplier of prestressed double-tee girders in South Dakota. The present study was carried out to investigate the feasibility and performance of an alternative precast bridge system for local roads incorporating precast full-depth deck panels and prestressed inverted bulb-tee girders. A full-scale bridge specimen consisting of two interior girders and five precast panels was tested under fatigue and strength loading. No significant damage beyond shrinkage cracks was observed through the entire fatigue testing, and the overall bridge stiffness did not change. The load at the first cracking was higher than the equivalent AASHTO Service and Strength I limit states under strength testing, indicating sufficient performance. Based on the construction, testing, and cost analysis, it can be concluded that the proposed precast bridge system is a viable alternative to double-tee girder bridges.

In this study, the performance of precast concrete segmental bridge columns (PCSBCs) against truck impacts was numerically investigated and compared with a corresponding conventional monolithic column (CMC). The numerical results have shown that although the impact force time histories of the two columns were quite similar under the same loading conditions, the PCSBC showed a better performance in terms of the induced bending moment and shear force by high impact force due to shear slippage and joint rocking between concrete segments. Also, the damage and failure of PCSBCs were localized at the two bottommost segments due to compression damage and/or combined flexural and shear failure of the concrete segment, whereas failure of the CMC distributed widely with flexural cracks, shear cracks, and punching shear at multiple sections. Furthermore, the base segment, which was found to absorb about 80% of the total absorbed energy of the PCSBC, played a crucial role in controlling the failure of the PCSBC. An analytical method to estimate the bending moment required to open the segment joint and the ultimate bending moment was also developed with consideration of the dynamic increase factor and the increase in axial force associated with stress wave propagation in the column induced by impact load.

Precast concrete (PC) deck systems have several advantages over cast-in-place (CIP) concrete decks in bridge construction, such as improved quality, reduced construction duration, and less dependence on weather and site conditions. A new PC deck system was developed and implemented in the construction of the Kearney East Bypass project in Nebraska. The new system consists of full-depth full-width PC panels with covered shear pockets to minimize deck surface penetrations and eliminate deck overlay. Deck panels are pretensioned in the transverse direction and posttensioned in the longitudinal direction using a new approach that is ductless and easy to install. The study presents the live load testing of the twin bridges constructed in that project: the southbound bridge constructed using CIP concrete deck and the northbound bridge constructed using the new system. Two loaded trucks were used to evaluate and compare the performance of the two deck systems. Relative displacements between adjacent deck panels, and between deck panels and girders, were measured. Testing results indicated that the new system behaves as fully composite with the girders, and its posttensioned system is satisfactory. Finite-element analysis (FEA) was conducted to model the new deck system and compare measured and predicted strains and deflections.

The vast majority of research studies on vehicular collision with bridge piers have been carried out with single-unit trucks, which are typically classified as medium-duty vehicles weighing about 90 kN (20,000 lb). Yet, collision events that involve severe bridge damage are generally caused by heavy-duty trucks, generally tractor-semitrailers weighing 360 kN (80,000 lb). The handful of tests that were conducted to study heavy truck collisions used rigid piers, which means that the energy absorption potential of the piers, and their failure mechanisms, were neglected. In this study, validated, high-fidelity finite-element simulations of collisions between heavy-duty tractor-semitrailers and reinforced concrete bridge piers have been carried out to investigate the demands imposed upon, and the damage modes of, concrete piers. Trucks with three different weights and piers with six different configurations were used in the simulations. The approach speeds for the trucks ranged from 48 to 113 km/h. The simulation results showed that impact from the engine block usually delivered the highest peak force, which was closely associated with the impact velocity of the vehicle. Once the pier’s resistance has been compromised by this event, the subsequent trailer impact, which has a lower force demand but longer duration, causes further significant damage or even destroys the pier. The current provisions regarding vehicular impact demands in AASHTO requirements are critiqued based on the results of parametric simulations using the heavy truck model.

The paper presents an analytical pile–cap soil model to determine the lateral resistance of a pile cap in sandy soils and its contribution to the lateral resistance of the bridge pile group–cap foundation system of pinned or fixed pile head connections with the pile cap. The strain wedge (SW) model approach was adopted to incorporate the pile cap in an interactive pile group–cap foundation system. The proposed model allows the calculation of the mobilized passive and side shear cap–soil resistance based on soil, cap, and pile properties. The study demonstrated the contribution of the pile cap in sandy soils to the total pile group–cap bridge foundation system (i.e., the bridge foundation lateral stiffness), which could approach 50% of the total pile group–cap lateral resistance. Such relative contribution varied with lateral deflection and the soil around the cap and pile group as well as the rotational restraint of the pile head–cap connection. The proposed technique was validated through comparisons with full-scale load tests.

The development of fatigue cracks in orthotropic steel bridge decks is a problem that bridge engineers are facing and need to solve urgently. A modified overlay is usually used to strengthen an orthotropic steel bridge deck, and the strengthening effect of the modified overlay is the primary focus of attention of this paper. To compare the mechanical property and stability of different strengthening solutions, a simply supported steel box girder bridge was strengthened using the sandwich plate system (SPS) and reactive powder concrete (RPC) solutions. Based on actual bridge data, the authors conducted a 7-year in situ mechanical performance test and follow-up investigation on the service conditions of the orthotropic composite steel bridge deck. Research results show that the mechanical performance and deformation of the longitudinal ribs and decks were both significantly improved. For SPS and PRC, the average stress on longitudinal ribs (decks) has been decreased by 52% (70%) and 81% (95%), respectively. Similarly, the deflection of longitudinal ribs (decks) was improved by 70% (75%) and 82% (86%), respectively. Moreover, no apparent degradation of mechanical performance was observed; the improving effects on the average stress of the SPS and PRC solutions were relatively stable. In addition, the stress and deformation of the SPS steel composite deck were positively correlated with temperature. Furthermore, serious damage in the initial overlay of the SPS solution were observed during the test. Based on a comparative analysis with a case in Germany and finite-element analysis, the effects of ambient temperature, the structure type of the deck, and the thickness of the SPS system should be taken into consideration when the SPS is applied to those bridges built in subtropical or tropical zones.

This article focuses on the fatigue failure of stringer-to-floor beam (SF) welded connections, which are sensitive to fatigue cracking in the orthotropic steel decks (OSDs) of railway bridges. Two full-scale SF welded connections were fabricated and tested. Eccentric loads were introduced to the specimen so that the adverse conditions of longitudinal bending of the stringer could be considered. Static loading was first conducted to measure the elastic strain distributions at potential hot spots where high stress levels are expected. Structural hot-spot stresses at weld toes and stress-concentration factors (SCFs) were quadratically extrapolated, and the critical locations of stress concentrations were subsequently identified. Constant-amplitude cyclic loading was subsequently carried out, by which the fatigue cracking process, fatigue failure mode, characteristic fatigue life, and rigidity degradation were obtained. All cracks were observed on the web of the floor beam and near the weld toes under the stringer’s bottom flange. It was determined that the propagation of cracks can be divided into three main stages, and the variations of crack length on the surface and of crack depth in the plate thickness were also revealed. The fatigue life before the crack ran through the plate thickness was found to be dominant for the whole life of crack propagation. Comparison between experimental numbers of cycles and standard S-N curves indicates that two of the recommended curves provided in current bridge design specifications can be used to estimate the fatigue resistance of such SF welded connections where double-sided fillet welds are adopted. Double-sided groove welds with partial or full penetrations are also recommended to improve the fatigue behaviors of such connections further.

For a bridge located in a seismically active and flood-prone region, the occurrence of earthquakes combined with flood-induced scour is a highly possible multihazard event. This study quantifies the scour effect on the seismic performance of a single pylon cable-stayed bridge under bidirectional earthquake excitations. Three-dimensional finite-element models, considering the nonlinear soil–structure interaction, the flexure–shear behavior of the bridge pier, and the hydrodynamic force applied to bridge structures, are built on the OpenSees platform. Several scour depths are considered in this study to represent various scour intensities within the service life of the cable-stayed bridge. The modal analyses indicate that the periods of the few vibration modes (fourth and fifth modes) of the cable-stayed bridge increase as the scour progresses, and the scour effects gradually diminish for higher and lower vibration modes (first, second, and third modes). The results of the nonlinear time history analyses indicate that the moments on the piles increase as scour progresses, while the moment demand of the pier decreases. The moment in the pylon of the scoured bridge is much larger than the intact bridge due to the higher pounding potentials with the increase of scour depth. Obviously, the failure modes of the cable-stayed bridge transform from the pier to the piles and the abutments. In addition, the impact of the hydrodynamic force on the seismic response of the bridge is negligibly small. The findings of this study can be used to guide the seismic design and the retrofitting of cable-stayed bridges under scour-critical conditions.

This experimental study was the first to evaluate the galvanic corrosion risk of using galvanized ASTM A325 Type I bolts with ASTM A1010 steel girders in the construction of A1010 steel bridges. The emerging construction of A1010 steel bridges is intended to extend the service life of bridges and reduce the need for maintenance under atmospheric corrosion attack, particularly in regions subject to severe saline exposure. However, combining high-corrosion-resistant A1010 steel with connection bolts that have a lower corrosion-resistance rating can lead to galvanic corrosion that accelerates the metal dissolution of bolts after installation and while in service. The results of this study indicate that under light saline exposure, the galvanic corrosion rate of galvanized ASTM A325 bolts used with A1010 steel was similar to the corrosion rate of A325 bolts used with ASTM A588 weathering steel. Under heavy saline exposure, however, the galvanic corrosion rate of A325 bolts was significantly higher when used with A1010 steel than when used with A588 weathering steel. Reducing the galvanic corrosion rate can be achieved by painting the joints of the steel girders, thereby reducing the cathode-to-anode area ratio. The results of this study suggest that the corrosion compatibility of the bolt and steel materials must be considered when designing corrosion-resistant A1010 steel bridges, and that the compatibility must be confirmed with an experimental validation.

Obvious differences exist among the design provisions for interface shear transfer between concretes cast at different times (that is, cold joint) in current codes. The purpose of this study is to evaluate the applicability and accuracy of cold joint shear transfer provisions. Ten push-off tests on high-strength concrete with a cold joint were carried out in this paper, and the interface shear transfer mechanism was studied based on the tests. A database of 97 cold joint push-off test results of shear resistance, which was composed of the 10 test results from this paper and 87 test results collected from the literature, was created to evaluate the shear transfer provisions from the American Concrete Institute (ACI), AASHTO LRFD Bridge Design Specifications, the Precast/Prestressed Concrete Institute (PCI), and CSA-S6. The analysis results show that for the smooth interface condition, unconservative results may occur in using AASHTO in the case of low concrete strength; for the roughened interface condition, the experimental resistances are an average of 2.66 and 2.61 times greater than the nominal resistances from ACI and PCI, respectively, which indicates that ACI and PCI seem to be excessively conservative. Furthermore, whether for the smooth interface condition or for the rough interface condition, AASHTO and CSA-S6, which include the adhesion or cohesion term, have a higher accuracy and stability than ACI and PCI. It is in accordance with the analysis result of the interface shear transfer mechanism that adhesion or cohesion between two surfaces that form the interface significantly contribute to the shear resistance of the interface. In addition, the experimental-to-nominal shear resistance ratio k of all code provisions is positively correlated with the concrete strength, while no obvious relationship between k and the clamping stress of shear reinforcement is noted.