Search Results (60)

Adjacent existing box girder bridges should be spliced in the long-span bridge expansion project. A type of integral splicing composite structure for connecting the adjacent flange plates is designed herein. The mechanical characteristic of the integral splicing composite structure is tested using a local full-scale model, and a refined simulation model is also proposed for the optimization of the integral splicing composite structure. The loop bar in the joint connection segment and the application of Ultra-High-Performance Concrete (UHPC) material can guarantee the effective connection between the existing flange plate and the splicing structure. The embedded angled bar can delay the interface debonding failure and interface slip. The UHPC composite segment below the flange plate (segment CF) can bend together with the existing flange plate. In this study, an innovative integral splicing composite structure for a long-span bridge extension project is proposed and verified using both a local full-scale model test and finite element simulation. The adaptation of UHPC material and loop bar joint connection form can meet the cracking loading requirements of the splicing box girder structure. By proposing a refined simulation model and comparing the calculation result with the test result, it is found that the flexural performance of the integral splicing composite structure depends on the size of the composite segment below the flange plate (segment CF). Increasing the width of segment CF is beneficial to delay the interface debonding failure, and increasing its thickness can effectively delay the cracking load of the flange plate. Finally, the scheme of segment CF with one side width of 200 cm and a minimum thickness of 15 cm can improve the flexural resistance of the spliced structure and avoid the shear effect caused by the lane layout scheme and the location of the segment CF end. Through the research in this paper, the reasonable splicing form of a long-span old bridge is innovated and verified, which can be used as a reference for other long-span bridge splicing projects. Full article

Thousands of multi-span, simply supported beam bridges with short or medium spans have been built in China. They often suffer from problems of cracks in the link slabs over piers, and the deterioration and damage of deck expansion joints at abutments. To address these problems, one approach is to retrofit them by converting the simply supported box beams into continuous structures over the piers and jointless bridges over the abutments. This paper discusses the design methodology and details for retrofitting the Jinpu Bridge in Zhangzhou, Fujian, China, from a simply supported bridge into a semi-integral bridge, in which semi-fixed dowel joints are used to connect the superstructure and the substructure, including piers and abutments. Simultaneously, the finite element software is used to calculate the internal forces and displacements of the structure. The analysis reveals an 11.1% reduction in the maximum positive moment at the midspan of the main beam in the semi-integral bridge compared to the simply supported bridge. However, the shear forces at the interior pier increase by 6.4%. According to the response spectrum analysis, the maximum longitudinal displacement of the semi-integral bridge’s main beam is 11.6 mm, reduced by 80.1% compared to the simply supported bridge under a dead load and earthquake effects. The maximum bending moment and shear force on the pier of the semi-integral bridge are 984.7 kN·m and 312.6 kN, respectively, both below their ultimate bearing capacities. The maximum displacement at the top of the pier is 7.7 mm, which is below the allowable 52.4 mm displacement. The calculated results conform to the design requirements specified by the code. Full article

Bridge expansion joints are critical components that accommodate the movement of a bridge caused by temperature fluctuations, concrete shrinkage, and vehicular loads. Analyzing the spatiotemporal deformation of these expansion joints is essential for monitoring bridge safety. This study investigates the deformation characteristics of Hongtang Bridge in Fuzhou, China, using synthetic aperture radar interferometry (InSAR). We optimize the network paths to enhance the phase unwrapping process of InSAR. Additionally, to address design matrix bias resulting from inaccurate temperature data, we employ the mixed total least squares method to estimate deformation parameters. Subsequently, we utilize independent component analysis to analyze the spatiotemporal deformation characteristics of the bridge. The average standard deviation of the unwrapped phase and the modeling residuals have been reduced by 87% and 5%, respectively. Our findings indicate that thermal expansion deformation is primarily concentrated in the expansion joints, measuring approximately 0.6 mm/°C. In contrast, the cable-stayed bridge deck exhibits the largest deformation magnitude, exceeding 2.0 mm/°C. This research focuses on bridge structures to identify typical deformation locations and evaluate their deformation characteristics. Such analysis is beneficial for conducting safety assessments of bridges. Full article

The high- and low-temperature performance of asphalt-based seamless expansion joints seriously affects road performance. The purpose of this paper is to explore the application of thermosetting epoxy asphalt-based materials in bridge expansion joints. The composite modification of asphalt was performed using Styrene–Butadiene rubber (SBR) and Styrene–Butadiene–Styrene (SBS) copolymer. The study then investigates the impact of five different dosages of SBR/SBS-modified asphalt on the performance of epoxy asphalt. The results of the cone penetration test, tensile test, and stress relaxation test of SBR/SBS-modified epoxy asphalt (SSEA) and BJ200 (a commercial Seamless expansion joint material) were comparatively analyzed. The Marshall test, rutting test, three-point bending test, and freeze–thaw split test were used to evaluate the road performance of SSEA mixtures. The test results show that with the increase in asphalt content, the shear resistance and tensile strength of SSEA decrease, and the low-temperature relaxation ability and elongation at break increase. The content of SBR/SBS-modified asphalt has a positive effect on the low-temperature performance of SSEA mixtures, and the residual stability in water and freeze–thaw splitting strength ratio (TSR) are higher than that of BJ200. Based on the requirement of balancing high and low-temperature performance, SSEA-3 has the best overall performance, and the dosage of SBR and SBS modifier is 12% and 2.5%, respectively. The ratio of epoxy resin, SBR/SBS-modified asphalt, and the curing agent is 1:4:1.6, and its use is recommended in areas with slight temperature differences. Full article

Ultra-high-performance concrete (UHPC) is a recently emerged material with exceptional durability and ductility. While widely used in bridge retrofitting, particularly to replace expansion joints and deck overlays, UHPC has seen limited use in jacketing piers for the improvement of lateral load resistance. It presents superior mechanical properties and deformation resilience, enabled by the distributed fibers and the dense microstructure, providing corrosion resistance and a maintenance-free service life. The significant tensile strength and ductility establish UHPC as an attractive resilient jacketing system for structural members. The experimental literature documents the effectiveness of this solution in enhancing the strength and ductility of the retrofitted member, whereas premature modes of failure (i.e., lap splices and shear failure in lightly reinforced piers) are moderated. A comprehensive database of tests on UHPC-jacketed piers under lateral loads was compiled for the development of practical guidelines. Various UHPC jacket configurations were evaluated, and detailed procedures were developed for their implementation in bridge pier retrofitting. These procedures include constitutive models for UHPC, confined concrete, and the strengthening of lap splices, flexure, and shear resistance. The results are supported by the database, providing a solid foundation for the broader application of UHPC in improving the lateral load resistance of bridge piers. Full article

Cement Asphalt Mortar (CAM) is widely applied in infrastructure, particularly in railways, bridge expansion joints, and pavements, due to its combination of cement’s load-bearing capacity and asphalt’s flexibility. Conventional CAM formulations, however, often encounter challenges such as extended setting times, high shrinkage, and limited durability under extreme environmental conditions. This study addresses these limitations by integrating bio-oil and polymer additives to enhance both the sustainability and performance of CAM mixtures. CAM mixtures were evaluated with cement-to-asphalt emulsion (C/AE) mass ratios of 75:25 and 50:50, incorporating bio-oil contents of 2% and 4% by mass and latex–acrylic polymer proportions ranging from 1% to 2% by mass. The optimized mix design, with a 75:25 cement-to-asphalt emulsion (C/AE) mass ratio, 2% bio-oil, and 1.5% polymer, improved flowability by 25%. This formulation achieved a flow diameter of approximately 205 mm and reduced the flow time to 72 s. Compressive strength tests indicated that this formulation reached an early-stage strength of 10.45 MPa (a 20.8% improvement over the control) and a 28-day strength of 24.18 MPa. Thermal stability tests at 45 °C demonstrated that the optimized CAM retained 86.6% of its compressive strength, compared to a 25% reduction in unmodified mixtures. Chemical resistance assessments in 5% sulfuric acid and 5% sodium hydroxide solutions showed strength retention of 95.03% and 91.98%, respectively, outperforming control mixtures by 17% and 13%. SEM examination revealed a dense, cohesive microstructure, reducing shrinkage to 0.01% from 0.15% in the control. These findings underscore the potential of bio-oil and latex–acrylic polymers to improve the performance and sustainability of CAM mixtures, making them well suited for resilient, rapid-setting infrastructure applications. Full article

Expansion joints render bridge structures highly vulnerable to damage during strong ground motions. Failures of expansion joints triggered by earthquakes not only jeopardize the post-earthquake serviceability of the bridge but also have a significant impact on the bridgeâs overall seismic performance. Despite extensive investigations and efforts to integrate these measures into design specifications aimed at mitigating the consequences of relative movements between adjacent bridge spans, major earthquakes have still revealed instances of damage related to expansion joints. On 6 February 2023, strong earthquake sequences occurred in KahramanmaraÅ, Turkey, with magnitudes of M7.7 and M7.6. The fault lines and epicenters of these shallow earthquakes were near the city and town centers and caused severe structural damage to buildings and infrastructures. There are approximately 1000 railway and highway bridges in the earthquake-affected region. Although both highway and railway bridges have generally performed well, some bridges experienced structural damage during the KahramanmaraÅ earthquakes. A large number of damage on the bridges is due to pounding and opening relative movements in expansion joints. This paper presents a comprehensive seismic evaluation of expansion joint failure mechanisms on bridges without viscous dampers during the 2023 KahramanmaraÅ earthquake sequences and an in-depth investigation into the seismic performance of bridge expansion joints equipped with viscous dampers and shock transmission unit devices are implemented utilizing the strong ground motion data collected throughout the earthquake sequences. It can be stated that the near-fault induced significant directivity and fling effects, resulting in notable velocity pulses and permanent tectonic deformations, and that these effects contributed to the failures of expansion joints, viscous damper devices, pot bearings, and shear keys. Full article

In order to improve the basic pavement performance of high-elastic asphalt concrete filled in the expansion longitudinal joints of seamless bridges, rubber particles and polyester fibers were added to optimize the mix proportion of elastic asphalt concrete, and the optimal asphalt–aggregate ratio was determined. The influence of rubber particles and polyester fibers on the basic pavement performance of high-elastic asphalt concrete was studied. The results show that when the dosage of polyester fiber is not more than 0.6%, the optimal asphalt–aggregate ratio is 1:5, and when it exceeds 0.6%, the optimal asphalt–aggregate ratio is 1:4. The incorporation of rubber particles reduces the compressive strength of high-elastic asphalt concrete but enhances its high-temperature stability, fracture performance, and deformation recovery ability. The incorporation of polyester fibers improves its compressive strength, high-temperature stability, fracture performance, and deformation recovery ability. In addition, the incorporation of rubber granules and polyester fibers promotes the use of green building materials and provides strong support for sustainable building practices. Full article

With the rapid development of China’s transportation network, the demand for bridge construction is increasing, the traffic volume is increasing yearly, and the average vehicle speed and the frequency of overloaded vehicles crossing bridges are soaring. When a vehicle passes over a highway bridge, it can easily form a coupling vibration between the vehicle and bridge due to the excitation of the expansion joint, the unevenness of the bridge deck, and the existing coating-hole. The impact effect is significant, which seriously affects the operation safety of both the vehicle and bridge, seriously damaging the service life of the bridge. Due to the influence of construction technology, it is common for the vibration to meet transverse and longitudinal expansion joints of a prefabricated girder bridge, where an aging bridge deck frequently results in bulges and potholes in asphalt pavement. The bridge vibration amplification effect under the dynamic load of heavy, high-speed vehicles is significant, and research about the large impact coefficient of bridges with local pavement deterioration is urgently needed. This study used SIMULINK simulation software and involved conducting several bridge model tests. Dynamic simulation analyses and running vehicle tests on scaled and real bridge models were carried out to study the coupling vibration response of bridge decks in the presence of different pothole sizes. The results show that the impact effect of low-speed vehicles passing through a larger-sized pothole is relatively significant, and the impact coefficient can be amplified to 214% of the original value under good road surfaces in extreme cases. The vehicle–bridge coupling impact effect of potholes is similar to bulges. This relevant work could provide suggestions for the operational performance evaluation and maintenance of bridges with local pavement deterioration. Full article

During strong earthquakes, pounding may occur on large-span bridges and their approach bridges. The effect and mitigation measures of such pounding have rarely been explored in previous studies. This paper primarily uses finite element models to investigate the pounding effects at the expansion joints between the main cable-stayed bridge and its approach bridge. Friction pendulum bearings (FPBs) and fluid viscous dampers (FVDs) are used to alleviate poundings. Furthermore, a detailed analysis is conducted on how the pounding effect of the isolated main bridge with FPBs and FVDs is affected by the wave passage effect, ground motion type, and soil type. This study reveals that FPBs and FVDs can effectively reduce pounding effects and the associated risks. Even with the installation of FPBs and FVDs, lower seismic wave velocities and near-fault seismic motions with pulse effects can significantly increase the pounding effects between the cable-stayed bridge and its approach bridge. Full article

Wood characterized by desired mechanical properties and wood joining material is essential for creating wooden structures. The polymer adhesives are suitable for such applications due to the possibility of energy dissipation from stresses generated by wooden structures and the elimination of thermal bridging, which are common problems in metal joining materials. This research focuses on the thermophysical properties of the laboratory-prepared flexible and rigid polyurethanes to select an appropriate polymer adhesive. Our results showed that the highest thermal stability was in the case of the new PSTF-S adhesive, which reached 230 °C, but the lowest mass loss in the air environment was around 54% for the PS material. The mean thermal expansion coefficient for F&R PU adhesives was 124–164∙10⁻⁶ K⁻¹. The thermal diffusivity of examined adhesives varied between 0.100 and 0.180 mm²s⁻¹. The thermal conductivity, depending on the type of polyurethane, was in the 0.13–0.29 W∙m⁻¹∙K⁻¹ range. The relative decrease in thermal diffusivity after heating the adhesives to 150 °C was from 2% for materials with the lowest diffusivity to 23% for the PU with the highest value of heat transfer. It was found that such data can be used to simulate wooden construction joints in future research. Full article

This study investigates the structural performance of assembled rib-plate bridge abutments (ARBAs) with two different connection methods: bull leg bolt and flange connections. In addition, we explored the bending and shear performance of the connection parts and related areas to assess the damage characteristics and modes of these ARBAs. Utilizing model testing, a numerical analysis was conducted to define the force performance of the ARBA, with reference to a cast-in-place rib-plate abutment. The research results indicate that the bearing capacity and deformation capacity of the cap part of the assembled ribbed slab abutment model with cow leg connections are lower than those of the cast-in-place structure. When the structure fails, a 45° diagonal crack develops from the cross-section at the mid-span joint to the connection between the rib slab and the cap, until the concrete protective layer at the joint is crushed, exhibiting a shear failure mode. The bearing capacity of the assembly rib plate type abutment cap connected by the flange plate is basically the same as that of the cast-in-place structure, and the deformation capacity is weaker than that of the cast-in-place rib plate type abutment. The expansion of structural cracks is consistent with that of the rib plate type abutment connected by the cow leg. When the flange plate at the mid span is damaged, the contact surface between the flange plate and the concrete is pried off, resulting in the inability of the structure to continue bearing, exhibiting a shear failure mode. Through numerical simulation, taking the stress performance of the integral cast-in-place ribbed slab abutment as a reference, the assembled ribbed slab abutment connected by the flange plate is basically consistent with the integral cast-in-place ribbed slab abutment in terms of ultimate load, concrete damage, and steel reinforcement skeleton stress, and the connection device has not yet reached the yield state. The ultimate displacement is slightly weaker than that of the integral cast-in-place ribbed slab abutment. By comparison, it can be seen that the ultimate bearing capacity of the assembled ribbed slab abutment connected by the flange is basically the same as that of the cast-in-place ribbed slab abutment, and the stress performance can reach an “equivalent cast-in-place”, making it the preferred solution for the assembled abutment structure. The finite element parameter analysis of the flanged ARBA revealed that the thickness of the stiffening ribs, the number of bolts, and length of the flange plate anchoring steel plate were proportional to the ultimate load-bearing capacity of the prefabricated ARBA. In the case of no change in the structural damage mode, considering the economic benefits and load-bearing capacity of the structure, the following parameter combinations of the flanged ARBA are recommended: a thickness of 30 mm of the stiffening ribs, the number of bolts is 12, and a length of 50 cm of the length of flange plate anchoring steel plate. Full article

In South Korea, the public infrastructure encompasses 172,111 facilities, with bridges accounting for a significant segment (totaling 34,199). These bridges undergo expansion due to traffic, vehicular loads, and temperature fluctuations. Expansion joint devices are installed to maintain vehicle stability and driving performance across expansion gaps. While these devices effectively ensure vehicular stability and performance, they do not address issues such as leakage and debris fall; therefore, rubber expansion joints should be installed. However, these rubber joints are prone to damage from various factors, resulting in secondary issues such as girder corrosion and accidents under bridges. Because of these inherent vulnerabilities, these joints require frequent replacements, making continuous bridge maintenance challenging. Therefore, this study explores the development of novel expansion joints using superelastic shape memory alloys to overcome the limitations of traditional rubber expansion joints. A comparative finite element analysis was conducted on the developed superelastic shape memory alloy and traditional rubber expansion joints. This study also assessed the long-term usability of these novel joints, particularly their ability to revert to their original shape post load removal. This research presents a promising alternative to conventional expansion joints and holds potential implications for enhancing the durability and safety of bridge infrastructure. Full article

To study how varying the parameters of expansion joints and bearing supports (E-B parameters) affects the dynamic response of a coupled vehicle–bridge system for curved girder bridges, a dynamic response analysis method for the coupled vehicle–joint (bearing)–bridge system, which takes into account centrifugal forces, was proposed and verified. Subsequently, taking a continuous curved box girder bridge as the prototype, the influence of the E-B parameters on the vehicle-induced dynamic response of the curved girder bridge was explored. The results showed that the dynamic amplification factor (DAF) of the middle beam of the expansion joint (DAF-EJ) and the main girder of the curved bridge (DAF-MG) were both significantly influenced by the E-B parameters. When there were height differences between the middle beam and side beam in the EJ, the DAF-EJ obviously varied, and the DAF-MG increased. When the EJ was damaged, the impact effect of the vehicle on the bearing support increased. The DAF-EJ and DAF-MG both increased with the decrease of the vertical support stiffness of the bearing support. The DAF-EJ was greatly affected by the single-support void at the near-slit end of the lane. The DAF-MGs at the beam end, the 1/4 point and 1/2 point of the first span, and the 1/2 point of the second span, were significantly affected by the single-support void near the measuring point. Compared with the single-support void, the DAF-EJ and DAF-MG more significantly increased under the double-support void. Variation in the height difference of the EJ had a more significant effect on the DAF-EJ and DAF-MG at the beam end, while a vertical stiffness reduction in the bearing support had a more significant effect on the DAF-MG. Full article

On 3 November 2023, a moment magnitude (M_W) 5.7 (Local Magnitude, M_L6.4) earthquake struck the western region of Nepal, one of the most powerful seismic events since 1505 in the region. Even though the earthquake was of moderate magnitude, it caused significant damage to several masonry buildings and caused slope failures in some regions. The field reconnaissance carried out on 6–9 November by the study team, following the earthquake, conducted the first-hand preliminary damage assessment in the three most affected districts—Jajarkot; West Rukum; and Salyan. This study covers the observed typical structural failures and geotechnical case studies from the field study. To have a robust background understanding, this paper examines the seismotectonic setting and regional seismic activity in the region. The observations of earthquake damage suggest that most of the affected buildings were made of stone or brick masonry without seismic consideration, while most of the reinforced concrete (RC) buildings remained intact. Case histories of damaged buildings, the patterns, and the failure mechanisms are discussed briefly in this paper. Significant damage to Khalanga Durbar, a historical monument in Jajarkot, was also observed. Medium- to large-scale landslides and rockfalls were recorded along the highway. The motorable bridge in the Bheri River suffered from broken bolts, rotational movement at the expansion joint, and damage to the stoppers. The damage observations suggest that, despite the existence of building codes, their non-implementation could have contributed to the heavy impact in the region. This study highlights that the local population faces a potential threat of subsequent disasters arising from earthquakes and earthquake-induced landslides. This underscores the necessity for proactive measures in preparedness for future disasters. Full article