Journal of Bridge Engineering

The need to demonstrate that a steel-reinforced concrete bridge pier wall resilient to strong earthquakes could be attained by the incorporation of glass fiber–reinforced polymer (GFRP) reinforcement has been brought to the fore by recent experimental results on GFRP-reinforced concrete bridge pier walls. The test results show that the GFRP bars assisted in crack recovery and the self-centering of walls between load reversals. Hence, GFRP bars could potentially be used to control the unrecoverable damage in steel-reinforced bridge pier walls after an earthquake. This study will use nonlinear finite element analysis (FEA) as a powerful tool to verify this expectation. A series of analyses will be implemented on concrete bridge pier walls reinforced with either steel or GFRP bars to demonstrate that the finite element (FE) procedure can provide quick and reliable simulation. The study is then extended to investigate the effect of using hybrid reinforcement through a comprehensive parametric study. Different configurations of GFRP bars are examined and compared with similar configurations of steel bars. The results show that hybrid reinforced bridge pier walls can undergo large displacements with minimal residual deformations. Nevertheless, a sensible selection of the GFRP bars location is necessary. The findings of this study could be considered as a fundamental step toward the development of code provisions for the use of hybrid GFRP/steel (GS) reinforcement in concrete bridge pier walls.

Accelerated bridge construction (ABC) is becoming progressively popular in China due to its advantages in sustainable development. However, some challenges still prevent it from being further widespread, especially in some harsh environments. As one of the greatest advances in material science, ultra-high-performance concrete (UHPC) is regarded as a competitive option for addressing the challenges of ABC due to its excellent material properties. A new cost-effective UHPC was developed with some modifications to weaken some adverse factors influencing the applications of UHPC in ABC, that is, high initial cost of material and steam/extreme heating curing requirements. Cost-effective UHPC is deemed to have the potential to build the critical zones of precast bridges, such as stress concentration zone, fatigue stress zone, inelastic deformation zone, harsh environment exposure zone, and late-cast joint zone, considering its material properties. In recent years, a series of tests have been done to investigate the cost-effective UHPC’s material properties and its structural elements’ mechanical behaviors. This paper systematically reports the cost-effective UHPC alternative for ABC from the laboratory tests on material properties and structural elements to real bridge implementations. Some challenges and future opportunities are presented for reference. The experimental results show that the cost-effective UHPC can have superior material properties and its structural elements can have satisfactory mechanical behaviors. Real engineering examples demonstrated that the cost-effective UHPC enables precast bridges to be lighter in weight, have higher strength, and support longer spans. The biggest challenge may be that more research and engineering examples are required to validate the feasibility of UHPC codes for cost-effective UHPC when it is applied in ABC.

This work focused on the damping effectiveness of additional longitudinal viscous dampers employed for seismic control of long-span cable-stayed bridges considering wave passage effects. A 1/35-scale physical model scaled from a typical long-span cable-stayed bridge was designed, constructed, and tested on four shake tables. The seismic responses of the systems with and without viscous dampers, under different types of ground motions considering uniform or traveling wave excitations, were analyzed and compared. The test results show that the damping effectiveness of the additional longitudinal viscous dampers was significantly reduced under near-field ground motion. The wave passage had a great influence on the displacement responses of the towers and the deck and the relative variation amplitudes of the cable forces near the midspan. Positive damping effectiveness was commonly achieved from the additional longitudinal viscous dampers under the far-field ground motions when considering the wave passage effect, whereas negative damping effectiveness was observed under the near-field ground motion at certain wave velocities.

Magnetorheological (MR) dampers are common methods that are used to mitigate cable vibrations with high effectiveness. Under the long-term effect of external loads and harsh environment, MR dampers will probably suffer from various durability problems, especially fluid leakage. Hence, accurate modeling and evaluation of the effect of fluid leakage of MR dampers are of great significance for bridge maintenance. This paper will investigate the mechanical behavior of MR dampers with fluid leakage after long-term operation and will evaluate their residual performance for cable vibration control. First, three MR dampers with fluid leakage will be selected from a real bridge, followed by a laboratory test to illustrate their damping force characteristics. Based on the experimental results, a theoretical model will be proposed to predict the mechanical behavior of the leaked dampers. A parametric analysis will then be conducted to show the effect of fluid leakage on the damping capacity. Then, one full-scale cable will be idealized as a taut string and the equation of motion for the cable-leaked MR damper system will be formulated. Additional modal damping provided by the MR damper will be determined numerically. The results show that fluid leakage could cause considerable slipping in the damping force. This slipping could lead to a remarkable reduction of the achieved additional modal ratios for the cables. The results of this paper could be of practical significance for the assessment of cable dampers performance and their maintenance on real bridges.

Biannual bridge inspections are federally mandated for hundreds of thousands of bridges in the United States. This represents a significant expenditure of labor and equipment resources. Lean engineering is a framework to improve the efficiency of processes, which was applied to the bridge inspection process in this work. Thirty-two routine bridge inspections were shadowed and analyzed as a four-stage process (consisting of document review, mobilization and demobilization, onsite inspection, and report writing) that included 52 distinct activities. Each activity that occurred during a shadowed bridge inspection was categorized as value added or by type of waste. Most of the time was considered value added, but several types of waste were identified for possible reduction. Statistical analysis showed significant differences in the duration of bridge inspection for certain bridge types and inspection equipment utilized. With the many aging bridges in the United States, utilizing lean engineering to identify areas for further improvement has the potential for reducing the effort of routine bridge inspection.

Until recently, ordinary concrete has been used to construct concrete-filled steel tube (CFST) arch bridges in China, which has resulted in the formation of circumferential gaps around steel–concrete interfaces. Furthermore, it has been found that harsh environments enlarge gaps, resulting in serious defects that decrease arch rib stiffness and even affect the dynamic features of the whole bridge. Hence, a finite element analysis and a reduced-scale model experiment were performed on a serviced CFST arch bridge rib member containing circumferential gaps to determine member tangent stiffness affected by the gap depth parameters under a small eccentric axial compression test. Next, tangent stiffness was applied to analyze the natural frequencies and modal vibrations of the whole bridge to study the influence of defects on bridge dynamic performance. A determination system was proposed for the effect of interface circumferential gaps on rib member stiffness and the dynamic features of the whole bridge. Therefore, this research provides a theoretical analysis method for CFST arch bridge maintenance and rehabilitation strategy.

The fatigue damage of steel bridges induced by heavy traffic loads is a critical problem worldwide. A uniform fatigue vehicle is generally adopted in bridge design codes to evaluate the cumulative fatigue damage of steel bridges. However, since the traffic loads vary across sites, a single vehicle with predetermined parameters may be imprecise for actual fatigue damage estimations. In this study, a new method for developing fatigue vehicle models that are applicable to various traffic conditions is proposed. The traffic in China was taken as an example for illustrating the proposed method. Numerical simulations were performed to investigate the fatigue damage distribution at 12 typical weigh-in-motion sites in China based on the collected vehicle load spectra, and the errors in fatigue damage estimations when adopting the fatigue vehicle Model III in Chinese bridge code were evaluated under various scenarios. Results showed that using Model III for fatigue analysis may seriously underestimate or overestimate the cumulative fatigue damage caused by the actual traffic loads under some conditions. Using a modified Model III with gross weight adjusted to the site-specific traffic condition could lead to a significant improvement, but the errors are still within a relatively large range. Following the classification and mathematical optimization techniques of the proposed method, a three-axle fatigue vehicle model and a four-axle fatigue vehicle model corresponding to the light and heavy traffic, respectively, were developed. These two fatigue vehicle models were proven to produce better and more consistent accuracy than the single fatigue vehicle model (i.e., Model III) for various traffic compositions in China.

The potential fatigue performance of a new type of rib-to-floor beam (RFB) connection for orthotropic steel decks, the slit connection, was investigated via finite-element analysis. The slit RFB connection combines aspects of the previously used fitted RFB connection and extended cut-out RFB connection. Various slit geometries, floor beam restraint conditions, floor beam geometries, finite-element analysis meshes, and loading conditions were studied. The results show that the slit RFB connection is well suited for orthotropic steel decks in bridge deck replacement applications, where the orthotropic deck is supported by existing, stiff, transverse floor trusses (or floor beams) that are often present in existing long-span cable-supported bridges.

Precast segmental reinforced concrete (PSRC) bridge piers have been widely used in bridges. Many experimental and numerical studies have been conducted to investigate the seismic and impact behavior of PSRC piers, but very limited effort has been completed on the blast resistance of PSRC piers. In this paper, reduced-scale field tests were performed on PSRC piers to study their behavior and failure mode under close-in blast loading, including one monolithic pier and 12 PSRC piers. The influences of some typical variables on the PSRC pier were investigated. Compared with the different failure modes between monolithic piers and PSRC piers under the bottom explosion, the experimental results show that the monolithic piers exhibit a localized flexural failure in the near explosion zone and numerous transversal cracks due to stress wave propagation vertically, while the PSRC piers show signs of localized punching shear failure at the bottom segment and vertical cracks due to concrete squeeze resulting from the relative rotation in other segments. Meanwhile, the PSRC pier with crushed concrete at the bottom segment collapsed completely under a smaller scaled distance. Under the middle explosion, the middle segments of PSRC piers experienced a flexural failure by showing bending deformation and concrete spalling. Through variable analysis, seven segments can reduce the localized residual deformation of the PSRC pier and small slenderness ratio can decrease the overall residual deformation of the PSRC pier. Shear key, ED bar, and the axial compression ratio of 0.1 can decrease the concrete damage including the concrete spalling and vertical cracks. Circular cross sections can effectively weaken the prestressing force loss due to small damage.

This paper will present a comparative study of tsunami-induced forces on box girder and T-girder bridges, which will be based on component level analysis. Component level analysis can explain the overall loading behavior and can further illustrate the reason for the difference in the forces between these two types of girder. First, in the numerical simulation, a three-dimensional (3D) dam-breaking model (at 1/20-scale) will be developed to generate bore-type tsunami waves. The Reynolds-averaged Navier–Stokes (RANS) equations, combined with the k−ɛ turbulence model will be utilized for the wave simulations. Then, the effectiveness of the numerical model will be verified with the experimental results. The tsunami-induced forces on the box girder and T-girder bridges will be compared and the differences will be discussed in detail based on the component level analysis. In addition, parametric analyses will be conducted to study the influence of the wave momentum flux and still water level (SWL). The results show that: (1) the T-girder bridge witnesses higher and longer-lasting horizontal peak forces. The box girder bridge had significantly larger upward forces than the T-girder bridge, (2) for both type of girders, the upstream web and upstream deck were the major contributors to the maximum horizontal and vertical forces, respectively. Special attention should be paid to the local damage to these components, (3) when the wave is high enough to impact on the whole girder, the differences caused by the girder shape on the horizontal impulse loads can be negligible, and (4) the difference in the vertical impulse loads between these two types of girders continually increases with the momentum flux. For the large momentum flux cases, the vertical impulse loads on the box girder could be 1.7–2.2 times that on the T-type girder.

The aerodynamic shape of the bridge deck has a significant influence on the wind resistance performance of the bridge, while the web inclination angle of the box deck plays a critical role in terms of the aerodynamic geometry. In order to investigate the effect of the web inclination angle on the aerostatic performance of the box deck and the aerostatic torsional divergence of the bridge, a series of web inclination angles (43 representative angles) were studied based on the computational fluid dynamics (CFD) method and the nonlinear aerostatic analysis. The results showed that there was a suction zone at the junction of the bottom slab and the inclined web when the angle of the web was small, which generated a downward force and decreased the lift coefficient of the box deck. It can also be concluded that the vertical and torsional displacements of the box deck under any wind speed were effectively reduced by reducing the web inclination angle, and selecting a box deck with a lower web inclination angle can reduce the lift coefficient and drag coefficient of the box deck. Consequently, it can well improve the aerostatic performance of the bridge.

Triple-tower suspension bridges with two asymmetrical main spans can adapt to complicated terrain conditions. If the top and bottom main cables with different sags are used on the two main spans, the longitudinal constraint on the central tower can be significantly improved, which is more conducive to the promotion and application of three-tower suspension bridges. Based on the widely used multisegment catenary theory, this paper proposes an analytical calculation method to determine the main cable shape in three structural states: completed bridge state, under live load action, and free cable state. In the completed bridge state, each span is solved independently, with the longer main span being calculated first. The two main spans and two side spans require an altitude difference closure condition, while the two anchor spans require an altitude difference closure condition and a splay-saddle moment balance condition. Under live load, due to the media effect of tower displacement and splay-saddle rotation, all spans need to be solved simultaneously. In addition to the conditions of altitude difference closure and splay-saddle moment balance, conditions such as span length closure and main cable unstressed length conservation are required. In the free cable state, due to the media effect of the cable saddle preoffset, all spans need to be solved simultaneously. The solution is similar to that under live load, and thus, it only requires minor modifications of the equations corresponding to live load. During the calculation of these main cable shapes, the deformations and internal forces induced by the live load, together with key construction parameters including the unstressed length of the main cable, the saddle preoffset, the elevations of free cable, and the installation positions of cable clamps can also be calculated. The method proposed in this paper is applied to a double-cable suspension bridge spanned as 248 m + 860 m + 1,070 m + 310 m. The cable shape of the completed bridge is determined first. Subsequently, the deformations and internal forces under live load are calculated for two cases: live load covered in the longer main span and live load covered in the shorter main span. Finally, the cable shapes and construction parameters of the two free cable states, that is, the bottom-cable-only state and the double-cable state, are calculated. This example is employed to verify the effectiveness of the approach presented in this paper. Some useful conclusions are also obtained, which lays the foundation for the promotion of this bridge type.

The purpose of this study was to evaluate a nonproprietary ultrahigh-performance concrete (UHPC) mix design in terms of bond strength and behavior as a slab joint material. Composite modulus of rupture and direct pull-off tests were conducted to evaluate bond strength using sandblasted, wire-brushed, and exposed aggregate substrates. The two methods for obtaining a saturated substrate included covering the substrate with wet burlap or power washing the substrate and either leaving pooled water or patting the surface dry. In addition, several specimens were constructed by joining two full-scale normal strength concrete slabs with a UHPC joint containing shortened reinforcing bar embedment lengths. These specimens were used to evaluate structural behavior when subjected to both static and cyclic loadings. Each test was compared to an identical test using the proprietary UHPC product Ductal. Bond testing showed that power washing of the substrate was required to produce comparable bond strengths to Ductal. For full-scale slabs, the nonproprietary mix performed comparably to Ductal as a bridge joint material, despite having lower compressive strength.

An innovative steel–concrete joint (SCJ) was applied to long-span railway hybrid box girder cable-stayed bridges to achieve favorable force transfer and deformation performance with a running train. The fatigue performance of each component was investigated by performing a full-scale 3 million cycle fatigue test. All components remained intact over the first 2 million cycles, indicating sufficient fatigue resistance over the designed service life. Turning points appeared in the curve for the shear stud on the first layer of the bottom plate and top plate after loaded 2.2 and 2.4 million loading cycles, respectively, resulting from the separation between the steel and concrete near end bearing plate, indicating that this area was the least favorable aspect of this innovative SCJ. Cracks then developed at the weld joint between the top plate and the end bearing plate after 2.4 million loading cycles, indicating that the fatigue life of the weakest weld joint exceeded 167.5 years. Numerical analysis with a nonlinear finite-element model was developed to further investigate the fatigue performance of the SCJ. The results indicated that the thickness of the end bearing plate and diameter of the shear studs significantly influenced the fatigue performance, and a 44–70-mm-thick end bearing plate and no less than 19-mm shear stud diameter is accordingly recommended. The outcomes of this study provide a reference for the further application of SCJ technology to long-span railway hybrid girder cable-stayed bridges.

Different types of connections have been used in practice to simulate a hinge behavior at the base of bridge columns. Previous earthquakes demonstrated that none of them could remain elastic and damage free during the seismic events, and thus did not satisfy the code requirements. To address this shortcoming, base pipe pin connections were developed. Cyclic loading studies of base pipe pins incorporated at the base of a scaled two-column bent model showed promising results. This paper presents the results of comprehensive analytical studies conducted on base pipe pins under lateral loading. An elaborate finite element model of the pins was developed using ABAQUS, and the accuracy of the modeling was evaluated based on the correlation with experimental results. The verified model was used to investigate the effect of different parameters on the seismic performance of the pins. Results of the parametric studies led to a series of detailing recommendation for optimized design of base pipe pins as capacity protected members.

Experimental bridge testing often produces large data sets that may have applicability to many analysis goals within bridge engineering. To ensure the persistence of these records for future analysis, it is essential to properly collect, organize, and define data. A field-testing program was developed to capture the dynamic loading response of a simply supported, modular-construction bridge to medium and very heavy military vehicle loads that included detailed instrumentation layout and nomenclature assignments, deck surface condition simulators, and iterative tracked and wheeled vehicle testing plans. The result was a complete data set that includes adequate information to achieve various analysis objectives. This data set, and the process through which it was gathered, have the potential to increase the knowledge base related to the behavior of modular truss bridges, dynamic bridge effects in civilian and military contexts, and may generate results that could significantly improve mobility for select military vehicle types.

This experimental study evaluates the galvanic corrosion risk between stainless steel bolts and ASTM A1010 steel bridge girders. Two stainless steel structural bolts, ASTM A320 B8 Class 2 and A193 B6 stainless steel bolts, are studied, because they are currently deemed to be compatible with, and recommended for use in new A1010 steel bridge girders. In the electrochemical experiments, the galvanic coupling current and potential are obtained in aerated salt solutions that simulate chloride-laden environments for A1010 steel bridges. The results show that B6 stainless steel might not be adequate in corrosive environments, because it was found to suffer severe pitting corrosion, and the galvanic corrosion risk of using B8 bolts with A1010 steel was found to be negligible. This finding will be further validated by the visual examinations of bolted A1010 steel plates in salt spray testing and confirmed by the pitting corrosion of B6 washers used in an A1010 bridge after 1 year of service. This study demonstrates that the galvanic corrosion risk has to be studied through properly designed corrosion experiments, and deductions from conventional knowledge of the composition of materials and their corrosion resistance is not sufficient to understand the actual galvanic corrosion risk of dissimilar metals in bridge applications.

Post-installed reinforcing bars are often used to connect new concrete elements to existing concrete structures. Bridge designers frequently specify post-installed epoxy-coated reinforcing bars in anchorage applications due to their potential corrosion resistance compared to uncoated reinforcing bars. However, chemical adhesive manufacturers only publish the tensile bond strength of uncoated reinforcing bars post-installed with their products. This research examined what effects the epoxy coating had on the tensile bond strength and directly compared the results for epoxy-coated and uncoated reinforcing bars. Forty-eight confined pullout tests were conducted in uncracked concrete to promote bond failure. Bond failure was at the concrete/adhesive interface for epoxy-coated reinforcing bars and at the steel/adhesive interface for uncoated reinforcing bars. The ratio of the tensile bond strengths of epoxy-coated to uncoated reinforcing bars ranged from 0.94 to 1.04 and varied based on the chemical adhesive. A potential coating factor for use when calculating the nominal tensile bond strength of a post-installed epoxy-coated reinforcing bar is discussed.

The wind–rain-resistant performances of aeroelastic models of simplified suspension bridges and cable-stayed bridges at the erection stage are experimentally investigated. Several typical deck sections, i.e., two bluff decks, two thin flat plates, and a quasi-streamlined deck, are included to cover a wide range of possible alternatives. Under different conditions of wind speed, rainfall intensity, and initial attack angle, the vertical and torsional displacements at the deck end tips and middle sections are measured. The comprehensive measurement results reveal that in the possible and even extreme range of rainfall intensity, the aerostatic and aerodynamic responses are almost independent of the rainfall intensity for all testing cases, which may contradict with the intrinsic conception of most researchers in the wind engineering community. The results suggest that the rainfall loads effect on bridges are trivial, and it might be unnecessary to comprehensively investigate the rainfall loads on bridges similar with the considered cases.