Search Results (12)

The construction of highway bridges using continuous precast prestressed concrete girders provides an economical solution by minimizing formwork requirements and accelerating construction. Different ways can be used to integrate bridge continuity and enable the development of negative bending moments at piers. Continuous bridge connections enhance structural integrity by reducing deflections and distributing loads more efficiently. Research has led to the development of various continuity details, categorized into partial and full integration, to improve performance under diverse loading conditions. This review summarizes studies on both partial and fully integrated continuous bridges, highlighting improvements in connection resilience and the incorporation of advanced construction technologies. While extended deck reinforcement presents an economical solution for partial continuity, it has limitations, especially in longer spans. However, full integration provides additional benefits, such as further reduced deflections and bending moments, contributing to improved overall structural performance. Positive-moment connections using bent bars have shown enhanced performance in achieving continuity, though skewed bridge configurations may reduce the effectiveness of continuity. Ultra-High-Performance Concrete (UHPC) has been identified as a superior material for joint connections, providing greater load capacity, durability, and seismic resistance. Additionally, mechanical splices, such as threaded rod systems, have proven effective in achieving continuity across various load types. The seismic performance of precast prestressed concrete girders relies on robust joint connections, particularly at column–foundation and column–cap points, where reinforcements such as steel plates, fiber-reinforced shells, and unbonded post-tensioning are important for shear and compression transfer. Full article

To reduce the maintenance requirements during the service life of highway bridges and enhance the cracking resistance of concrete slabs in the hogging moment zone of continuous composite girders, this paper proposes an innovative girder-to-pier joint for composite bridges with integral piers. Compared to the existing ones, this new joint has structural differences. The middle part of the embedded web is hollowed out to facilitate the construction, and the upper and bottom flanges of the steel girder within this joint are widened. Moreover, cast-in-place ultra-high-performance concrete (UHPC) is applied instead of normal concrete (NC) only on the top surface of the pier. A full-scale test was carried out for this new joint to evaluate the load–displacement relationship, load–strain relationship, crack initiation, and crack propagation. Compared with the numerical simulation results of the reference engineering, the test results demonstrated that the proposed joint exhibited excellent flexural performance and cracking resistance. This paper also proposes a calculation method for the elastic flexural capacity of the girder-to-pier joint incorporating the tensile strength of UHPC, and the calculated result was in good agreement with the experimental result. Full article

Typical forms of seismic damage to laminated-rubber-bearing girder bridges in the transverse direction are falling beams, girder displacement, and bearing damage. However, the damage to piers and foundations is generally lighter. This is mainly due to slippage of the bearings. Therefore, we propose a new type of arc-shaped shear key to improve the lateral seismic performance. A 1/12-scale highway continuous-girder bridge isolated by different shear keys was tested utilizing a 4 m × 4 m shaking table with six DOFs. The seismic responses of the bridge were analyzed in terms of phenomenon, displacement, strain, and acceleration. The main girder and pier exhibited different seismic responses because the bridge had different stops. A numerical simulation based on FEM showed that the established finite element model can well reproduce the displacement time history of the main girder and the cap girder. By analyzing the finite element model, the relative displacement of the bearing under different seismic waves was obtained. A comparison between the measured and FEM responses showed that the arc-shaped shear key can well limit the displacement of the main girder and the bearing. In addition, it does not significantly amplify the seismic response of the substructure. The arc-shaped shear key dissipates more energy while limiting the displacement of the main girder, and the comprehensive seismic performance is better than that of the rubber pad shear key. Full article

Due to their distinct features, including structural simplicity and exceptional load-carrying capacity, steel box girder bridges play a critical role in transportation networks. However, they are categorized as fracture-critical structures and face significant challenges. These challenges stem from the overloading and the relentless effects of corrosion and aging on critical structural components. As a result, these bridges require thorough inspections to ensure their safety and integrity. This paper introduces generalized approaches based on vibration-based structural health monitoring in response to this need. This approach assesses the condition of critical members in a steel girder bridge and evaluates their sensitivity to damage. A rigorous analytical evaluation demonstrated the effectiveness of the proposed approach in evaluating the Szapáry multi-span continuous highway bridge under various damage scenarios. This evaluation necessitates extensive vibration measurements, with piezoelectric sensors capturing ambient vibrations and developing detailed finite element models of the bridge to simulate the structural behavior accurately. The results obtained from this study showed that bridge frequencies are sufficiently sensitive for identifying significant fractures in long bridges. However, the mode shape results show a better resolution when compared to the frequency changes. The findings are usually sensitive enough to identify damage at the affected locations. Amplitude changes in the mode shape help determine the location of damage. The modal assurance criterion (MAC) served to identify damage as well. Finally, the results show a distinct pattern of frequency and mode shape variations for every damage scenario, which helps to identify the damage type, severity, and location along the bridge. The analysis results reported in this study serve as a reference benchmark for the Szapáry Bridge health monitoring. Full article

When vehicles move on a bridge, the coupling effect between vehicles and bridges can affect driving safety and comfort, especially for curved bridges, therefore, choosing reasonable design parameters for curved bridges is crucial. In this article, a three-span curved continuous box-girder bridge was taken as the research object; the entire process of vehicle-bridge coupling vibration of highway curved girder bridges was conducted via numerical simulation and the vehicle-bridge coupling vibration analysis program Cmck 1.0 was developed. Then, the influence factors such as curvature radius, constraint mode, and vehicle characteristics on the vehicle-bridge coupling vibration of curved girder bridges were explored. The results showed that as the curvature radius increased, the dynamic response of the bridge offered a gradually decreasing trend and compared to the vertical dynamic response, the torsional response was more sensitive to the influence of the curvature radius. Different constraint methods significantly impacted the dynamic response of bridges, and the vertical and torsional dynamic responses of bridges under general constraint arrangement of straight bridges were increased compared to those under boundary conditions for curved beam bridges. As the axle load of the car decreases, the bridge mid-span vertical and torsional dynamic responses showed a decreasing trend. In contrast, the lateral dynamic response gradually increased. Full article

There are differences between the dynamic deflection and bending moment (strain) in the same section of continuous girder bridges. However, the selection of the response for calculating dynamic amplification factors (DAFs), which are essential for bridge health monitoring and safety assessment, remains controversial. Modes may play a role in the relationship between the deflection DAF and the bending moment DAF in both numerical analysis and field tests. To investigate the distinctions between the DAFs of the deflection and bending moment in a continuous girder bridge, functional expressions of the DAFs were derived, taking into account multi-factor coupling under concentrated forces. The interaction effects of the mode and road surface condition (RSC), vehicle speed, bridge span length, and span number on the deflection DAF, the bending moment DAF, and the ratio of the deflection DAF to the bending moment DAF (RDM) of precast continuous box-girder bridges were analyzed using vehicle-bridge interaction. To ensure the accuracy of the DAF in numerical computations and experimental tests, two types of accuracy indexes and the corresponding cut-off modes were provided. Validation was conducted by performing dynamic load tests on two field bridges. The results indicate that different modes have a significant effect on the RDM of the mid-span section of a bridge. When considering multiple factors, the deflection DAF and bending moment DAF of the mid-span section increased rapidly with the considered modes and then stabilized. Statistically, the RDM of all nine bridges ranged from 1.00 to 1.12, indicating that the deflection DAF was greater than the bending moment DAF. The suggested cut-off modes can be utilized for efficient and accurate calculation of the DAF and response signal fidelity. Full article

For the bridge widening of long multi-span highway concrete continuous box girder with a conventional splicing structure, due to the large longitudinal difference deformation by concrete shrinkage and creep between the existing and new ones, the widened structure will have an overlarge bending deformation after widening, especially an obvious transverse deformation at the end of girder, which will lead to structural damage to the newly widened structure. To effectively absorb the difference deformation mentioned above, this study proposes a novel transverse splicing structure based on the folding effect of a corrugated steel plate (CSP) (hereinafter referred to as “the CSP splicing structure”). Then, a finite element structural analysis was performed on the mechanical properties of the widened structure with the CSP splicing structure, and compared to those of a widened structure adopting the conventional concrete splicing mode, to clarify the transverse load transferring mechanism of the structure. Finally, by conducting a sensitivity analysis on CSP thickness, corrugation length, splicing stitch width, and other structural parameters, a sound parameter combination scheme was put forward. According to the research results, to ensure effective utilization of the CSP folding effect, the corrugation pattern direction of CSP should be set as horizontal, and the wave angle as the degree of 90°. In addition, it mitigated the transverse tensile stress to effectively avoid concrete cracking feasibility on the top flange of the box girder at the end of the girder. This study offers a feasible way of avoiding the structural damage produced by an excess transverse deformation at the end of the girder after bridge widening of a long multi-span concrete continuous box girder. Full article

Probabilistic seismic demand analysis (PSDA) is known as one of the critical intermediate steps in the performance-based earthquake engineering (PBEE) design framework. Accuracy of the PSDA is influenced by various sources of uncertainties and mostly by that stemming from the ground motion-related variabilities. By taking a representative reinforced concrete (RC) continuous girder bridge as the case study, twenty-eight commonly used seismic intensity measures (IMs) were investigated in terms of the effectiveness, efficiency, practicality, proficiency, and sufficiency assessments. Probabilistic seismic demand models (PSDMs) of several critical bridge engineering demand parameters (EDPs) were developed under both the near-field and far-field ground motions through the nonlinear time history analyses (NTHAs). In addition, effects of ground motion-related uncertainties, such as the bin-to-bin (BTB) and record-to-record (RTR) variabilities, on the PSDA of highway bridges were also investigated. It is concluded that (1) IM efficiency contributes significantly to reflecting the RTR variability of ground motions and an efficient IM may reduce the influence of RTR variability in the estimation of structural demands; (2) IM sufficiency reflects the statistical independence of IM and ground motion parameters, and a sufficient IM is helpful in rendering the prediction of structural demands; and (3) uncertainties stemming from both the BTB and RTR variabilities of the seismic records have significant influences on the PSDA and the developed PSDMs of highway bridges. Full article

Overloaded truck and earthquake have become two main factors responsible for bridge damage, consequently the combination of heavy truck and seismic loads as a typical occurrence of extreme events is likely to lead to bridge collapse or destructive damage, in which the crucial issues of coupling load model, dynamic equations and bridge responses have not been adequately addressed. In this study, a simplified vehicle-bridge model consisting of many containers is established to simulate vehicle passage, and the dynamic equations are derived for a 5-axle truck on a simply supported beam as an illustration. Then, five ground motions selected from PEER with appropriate peak ground accelerations and durations and the three truck models specified in American Association of State Highway and Transportation Officials, Caltrans and Chinese codes are applied on the finite element model of a typical reinforced concrete continuous girder bridge, in which, vehicle speed, number of trucks, ground motion and vehicle type are assumed to be random variables and their influences on dynamic responses of the bridge are analyzed. The results show seismic load is the governing factor in dynamic responses but truck load may change displacement shapes; in addition, dynamic responses present a high sensitivity with the number of trucks (set as truck platoon) and gross vehicle weight but rare with vehicle speed. Specifically, the presence of a few trucks could serve as energy dissipation facilities for the bridge under seismic motions but may amplify the response when more trucks involved; some combinations of truck platoon with seismic excitation produce very large displacements and even cracks on the bridge, therefore, such an extreme event requires higher robustness in bridge design to make it be sustainable and serviceability after earthquakes. Full article

Geosynthetic-reinforced soil (GRS) technology has been used worldwide since the 1970s. An extension to its development is the application as a bridge abutment, which was initially developed by the Federal Highway Administration (FHWA) in the United States, called the GRS—integrated bridge system (GRS-IBS). Now, there are several variations of this technology, which includes the GRS Integral Bridge (GRS-IB) developed in Japan in the 2000s. In this study, the GRS-IB and GRS-IBS are examined. The former uses a GRS bridge abutment with a staged-construction full height rigid (FHR) facing integrated to a continuous girder on top of the FHR facings. The latter uses a block-faced GRS bridge abutment that supports the girders without bearings. In addition, a conventional integral bridge (IB) is considered for comparison. The numerical analyses of the three bridges using Plaxis 2D under static and dynamic loadings are presented. The results showed that the GRS-IB exhibited the least lateral displacement (almost zero) at wall facing and vertical displacements increments at the top of the abutment compared to those of the GRS-IBS and IB. The presence of the reinforcements (GRS-IB) reduced the vertical displacement increments by 4.7 and 1.3 times (max) compared to IB after the applied general traffic and railway loads, respectively. In addition, the numerical results revealed that the GRS-IB showed the least displacement curves in response to the dynamic load. Generally, the results revealed that the GRS-IB performed ahead of both the GRS-IBS and IB considering the internal and external behavior under static and dynamic loading. Full article

Accelerated construction in the form of steel–concrete composite beams is among the most efficient methods to construct highway bridges. One of the main problems with this type of composite structures, which has not yet been fully clarified in the case of continuous beam, is the crack zone initiation that gradually expands through the beam width. In the current study, a semi-empirical model was proposed to predict the size of cracks in terms of small box girder deflection and intensity of load applied on the structure. To this end, a set of steel–concrete composite small box girders were constructed by the use of steel fibrous concrete and experimentally tested under different caseloads. The results were then used to create a dataset of the box girder response in terms of beam deflection and crack width. The obtained dataset was then utilized to develop a simplified formula providing the maximum width of cracks. The results showed that the cracks initiated in the hogging moment region when the load exceeded 80 kN. Additionally, it was observed that the maximum cracked zone occurred in the center of the beam due to the maximum negative moment. Moreover, the crack width of the box girder at different loading cases was compared with the test results obtained from the literature. A good agreement has been found between the proposed model and experiment results. Full article

This work describes a vibration-based structural health monitoring of a prestressed-concrete box girder bridge on the A100 Highway in Berlin by applying statistical pattern recognition technique to a huge amount of data continuously collected by an integrated monitoring system during the period from 2000 to 2013. Firstly, the general condition and potential damage of the bridge is described. Then, the dynamic properties are extracted from 20 velocity sensors. Environmental variability captured by five thermal transducers and traffic intensity approximately estimated by strain measurements are also reported. Nonlinear influences of temperature on natural frequencies are observed. Subsequently, the measurements during the first year are used to build a baseline health index. The multiple linear regression (MLR) method is used to characterize the nonlinear relationship between natural frequencies and temperatures. The Euclidean distance of the residual errors is calculated to build a statistical health index. Finally, the indices extracted from the following years gradually deviate; which may indicate structural deterioration due to loss of prestress in the prestressed tendons. Full article