Bridge Reinforcement Research Articles

Dynamic responses of large-diameter variable-section group-piles subjected to shaking-table tests with varying scour depths

Scouring leads to soil loss around piles, which, in turn, changes the ground-vibration characteristics and influences the seismic performance of bridges. In this study, the Xiang’an Bridge was used as a reference for constructing a large shaking-table test model to investigate the dynamic characteristics of the pore-pressure ratio of saturated sandy soils, accelerations, and bending moments of the piles, as well as the horizontal displacements of the pile-top at scouring depths of 10, 20, and 32 cm, with ground-vibration intensities ranging from 0.10-0.45 g. The results indicated that as the scour depth increased, the pile acceleration of the group piles increased and changed abruptly at the variable cross-section and soil-stratum interface. The peak values of the horizontal displacement of the pile-top and bending moment of the pile exhibited an increasing trend. As the ground-shaking intensity increased, the pore-pressure ratio of the saturated sandy soil, pile acceleration of the group piles, horizontal displacement of the pile-top, and bending moment of the pile body gradually increased, whereas the base frequency of the pile foundation gradually decreased. This study can serve as a reference for the seismic design and reinforcement of scour bridges in areas prone to seismic activity.

Holistic life cycle cost analysis of road bridges with non-metallic reinforcement

Corrosion-related damage due to exposure to environmental conditions is the main cause of costs in the maintenance of transport infrastructure. Because of its high corrosion resistance and the associated higher durability, non-metallic reinforcement offers great potential for preventing such damage, thus reducing maintenance costs. In this article, potential savings for an integral road bridge are studied through a holistic life cycle cost (LCC) analysis considering four different reinforcement materials (steel, glass, basalt, carbon). A fair comparison is enabled by a material-specific design, the calculation of maintenance and user costs and the consideration of the respective disposal scenario. Moreover, environmental costs are recognised by carbon pricing based on life cycle analysis (LCA). The influence of individual parameters is quantified by means of a sensitivity analysis and the probability of savings is studied by Monte Carlo simulation. It is shown that higher investment costs for non-metallic reinforcement can be compensated by lower user costs. This is mainly due to shorter maintenance periods, as less time is required for repair action, whereby potential savings in user costs are particularly evident if the traffic route below the bridge is not disrupted. It is concluded that even from today's perspective, the use of glass and basalt fibre-reinforced polymer (FRP) reinforcement in highway bridges with average traffic volumes very likely offers an economic advantage over corrosion-prone reinforcing steel.

Reinforcement of Insufficient Transverse Connectivity in Prestressed Concrete Box Girder Bridges Using Concrete-Filled Steel Tube Trusses and Diaphragms: A Comparative Study

To address the issue of insufficient transverse connectivity in prestressed concrete box girder (PCB) bridges, this study investigates two transverse strengthening methods—installing diaphragms and utilizing concrete-filled steel tube trusses (CFSTTs). A finite element model was developed for a typical 30 m PCB bridge and was validated by on-site load test results for reliability. Based on the deflection and load distribution of PCB bridges before and after reinforcement, as well as the maximum stress and strain of the diaphragms and the CFSTTs, comparative analyses were conducted on diaphragms of different thicknesses and materials, as well as on CFSTTs of various strength grades. The results show that the addition of a transverse partition and CFSTTs can effectively improve the load distribution of the PCB bridge and reduce the maximum deflection of the girder, especially when using the CFSTT reinforcement method. The unique structural design improves the reinforcement effect of the material in the post-elastic stage. When using CFSTTs, increasing the steel tube wall strength significantly reduces the maximum deflection of the main girder. For example, using steel tubes with yield strengths of 235 MPa and 420 MPa filled with concrete of 50 MPa compressive strength reduced the maximum deflections by 15.32% and 24.55%, respectively, and improved the load distribution coefficients by up to 7.31% and 11.57%. Additionally, steel diaphragms demonstrated better reinforcement effects compared with concrete diaphragms. The load transverse distribution coefficients for the CFSTT-reinforced PCB bridge were calculated using the hinge plate (beam) and the rigid plate (beam) methods, showing minimal differences between the two approaches. The findings of this study provide valuable insights into the design of diaphragm and CFSTT reinforcement in PCB bridges, aiding in the selection of optimal reinforcement strategies.

ИЗУЧЕНИЕ МЕТОДОМ КОНЕЧНЫХ ЭЛЕМЕНТОВ ЭФФЕКТА АРМИРОВАНИЯ СТЕКЛОВОЛОКНОМ ПРОВИЗОРНЫХ НЕСЪЕМНЫХ ПРОТЕЗОВ ИЗ АКРИЛОВОЙ И БИС-АКРИЛОВОЙ ПЛАСТМАССЫ

The use of interim (provisional) prostheses is an obligate stage of modern dental practice. The problem of provisional bridges recognized by most experts is their use under heavy occlusal stress due to the possibility of their fracture. The development of a simple method of reinforcing provisional of prostheses during a clinical appointment that does not require special equipment is an urgent scientific and practical task. Objectives. The goal of this study was to evaluate the stress distribution in fiberglass reinforced and non-reinforced short-span and long-span provisional bridges according to different acrylic and bis-acrylic resin. Methodology. For this purpose, four finite element models were developed to reproduce the properties of prosthetic materials and hard dental tissues (Young’s modulus, Poisson’s ratio, hardness). Each model was subjected to a vertical load of 100 N applied to the middle of the bridge. Calculations were carried out in APM 3D Studio, and the results obtained were monitored in Ansys 12.2. The results obtained were displayed on the monitor screen, printed and analyzed. Results. Stress distribution pattern for an acrylic non-reinforced short-span bridge (model 1) showed the highest stress (4.2–5.2 n/mm2) in the area of the occlusal surface. Stress distribution pattern for an acrylic non-reinforced long-span bridge (model 2) showed the highest stress (11.4–12.3 n/mm2) both in the load zone and in the cervical zones of the connector facing the defect. Stress distribution pattern for acrylic reinforced long-span bridge (model 3) showed the highest stress (10.5–12.0 n/mm2) in the area where the fiber reinforcing tape is located deep in the bridge. Stress distribution pattern for bis-acrylic reinforced long-span bridge (model 4) showed the highest stress (9.8–10.5 n/mm2) observed both in the area where the glass fiber reinforcing tape is located and on the occlusal surface. Conclusion. Finite element analysis confirmed the feasibility of fiberglass reinforcement of long-span provisional bridges made of acrylic or bis-acrylic resin.

Numerical Simulation Analysis of the Bending Performance of T-Beams Strengthened with Ultra-High-Performance Concrete Based on the CDP Model

Numerical Simulation Analysis of the Bending Performance of T-Beams Strengthened with Ultra-High-Performance Concrete Based on the CDP Model

Research on Quality Inspection and Reinforcement Technology of Road Bridge

With the acceleration of urbanization, road bridges play a crucial role in urban transportation, and their quality condition is directly related to traffic safety and urban development. The article analyzes the common problems of existing road bridges, mainly including cracks, settlement problems and other aspects, to provide a reliable basis for the maintenance and reinforcement of road bridges. Based on this, the article mainly researches the quality inspection technology of road bridges and the reinforcement technology of old bridges at the present stage, and analyzes the application of quality inspection technology and reinforcement technology in improving the structural quality of road bridges according to the construction cases of Jialingjiang Bridge, Qiuyun Bridge and Luoxi Bridge in Heyang, so as to improve the safety of road bridges and prolong the service life of bridges.

Enhanced YOLO v3 for precise detection of apparent damage on bridges amidst complex backgrounds

A bridge disease identification approach based on an enhanced YOLO v3 algorithm is suggested to increase the accuracy of apparent disease detection of concrete bridges under complex backgrounds. First, the YOLO v3 network structure is enhanced to better accommodate the dense distribution and large variation of disease scale characteristics, and the detection layer incorporates the squeeze and excitation (SE) networks attention mechanism module and spatial pyramid pooling module to strengthen the semantic feature extraction ability. Secondly, CIoU with better localization ability is selected as the loss function for training. Finally, the K-means algorithm is used for anchor frame clustering on the bridge surface disease defects dataset. 1363 datasets containing exposed reinforcement, spalling, and water erosion damage of bridges are produced, and network training is done after manual labelling and data improvement in order to test the efficacy of the algorithm described in this paper. According to the trial results, the YOLO v3 model has enhanced more than the original model in terms of precision rate, recall rate, Average Precision (AP), and other indicators. Its overall mean Average Precision (mAP) value has also grown by 5.5%. With the RTX2080Ti graphics card, the detection frame rate increases to 84 Frames Per Second, enabling more precise and real-time bridge illness detection.

A Study on the Suitability of Composite Material Failure Theory Applicable to Behavior Analysis of Wedge-Type Anchorage System for Road Bridge Reinforcement

A Study on the Suitability of Composite Material Failure Theory Applicable to Behavior Analysis of Wedge-Type Anchorage System for Road Bridge Reinforcement

Research on fatigue vulnerable details of cross beam joints after reinforcement for steel truss bridges

In this research, fatigue tests on full-size specimens are conducted for a steel cross-beam joint before and after reinforcement. Combined with a three-dimensional (3D) numerical simulation, the 3D stress parameters, and their redistribution rules study anew with a web crack and new crack initiation locations and fatigue weakness details are predicted. The research results include the following: 1) The empirical formula parameter m of the Z-axis stress for the new crack tip is approximately 0.05. 2) The fatigue performance of the web’s new crack tips is significantly improved by bolting reinforced steel plates, the stress range is reduced by 60%-98.78%, and the original crack stops growing in size. The health monitoring system can choose the predicted weak details as valid monitoring points so that the fatigue damage can be intelligently perceived after the reinforcement of steel bridges.

Case Study on Collision Accident Analysis and Repair·Reinforcement of Old Plate Girder Bridge

Case Study on Collision Accident Analysis and Repair·Reinforcement of Old Plate Girder Bridge

A new type of bridge structure reinforcement effect evaluation algorithm based on time series

A supplement method based on reusing the original bridge structure is suggested to expedite construction and reduce costs. Furthermore, theoretical analysis of the single pile bearing capacity is conducted, primarily involving the calculation of the bridge pile foundation settlement, horizontal resistance and axial bearing capacity. At the same time, considering that the time series data generated in the actual process often have characteristics of imbalance between classes, a cost-sensitive hybrid network model is also constructed. Its significance is the analysis of bridge reinforcement performance data. The experimental results show that compared with the cross-entropy loss function, the introduction of a cost-sensitive loss function can significantly improve the monitoring accuracy of abnormal data sets. The ACC– score, G-means and F-measures are higher than those of the specific cross-entropy loss function. The permissible bearing capacity of muddy clay determined using a network model complies with engineering standards in the evaluation of bridge reinforcement performance. As a result, the reliability of this form of reinforcement is improved.

Numerical Study on the Evolution Law of Explosion Response of Extra-wide Self-anchored Suspension Bridge under the Influence of Concrete Shrinkage and Creep

In order to deeply reveal the evolution law of explosion response of super wide self anchored suspension bridge under the influence of concrete shrinkage and creep, the evolution law of explosion response of extra-wide self-anchored suspension bridge under the influence of concrete shrinkage and creep is studied by simulation experiment. Based on a real bridge, the dynamic response of vertical displacement of the bottom plate of the bridge under explosion load at different ages is analyzed by numerical simulation. Firstly, the refined finite element model of the whole bridge is established by using SolidWorks software and Hypermesh software; Secondly, the explosion load is applied by ANSYS/LS-DYNA software and *LOAD_BLAST_ENHANCED (LBE) method, and the reliability of the calculation method is verified by combining the explosion test results of concrete members in the literature; Finally, the dynamic response of the bridge at different ages is analyzed by modifying the elastic modulus of the material to make the main girder reach the linearity predicted in the literature. The results show that under the action of explosion shock wave, the stress of the concrete element on the top plate of the main girder reaches the limit value and fails, forming an elliptical breach. With the increase of the age of the bridge, the vertical displacement of the bottom plate in the middle of the bridge span increases continuously, and the growth rate is “fast in front and slow in back”, which is consistent with the impact of concrete shrinkage and creep on the bridge. The results of this paper can provide an important basis for the anti-explosion protection and reinforcement of concrete extra-wide self-anchored suspension bridge.

Effect change of extra-wide concrete self-anchored suspension bridge under blast loads and its prediction considering time-dependent effect

In order to study the dynamic response of self-anchored suspension bridge with extra-wide concrete girder under explosive load, a real bridge was taken as the background, which is the widest on in China at present. Firstly, the refined finite element model (FEM) of the whole bridge was established. The reliability of numerical simulation method was validated by the measured data of the bridge at completion state and explosive test results of scaled girder specimen. The vertical displacement, reinforcement strain, acceleration and failure characteristics of the girder specimen under the explosive load of 3 kg TNT were analyzed. Through parametric simulation, the effects of different scale distance, concrete strength and reinforcement ratio on the explosion response of girder specimen were studied. Secondly, the dynamic responses of girder were studied. Finally, the change law of dynamic response at different ages was analyzed. The results show that the elliptical crack is formed on girder top plate. The maximum girder vertical displacement reaches 135.9 mm under 1000 kg, and the maximum increasing ratio of hanger force is 27%. The influence brought by the extra width of girder is significant. The girder vertical displacement changes along transverse direction and the concrete breach sizes are different. In addition, with the increase of service age, the girder displacement increases from 60.50 mm to 106.16 mm under the same explosive load. The research results can provide an important basis for the anti-explosion protection and reinforcement of similar extra-wide concrete self-anchored suspension bridge.

Experimental and Numerical Investigation of the Anti-Overturning Theory of Single-Column Pier Bridges

In recent years, overturning accidents at single-pier bridges have occurred frequently, resulting in significant property losses and safety accidents. Overturning accidents show that there are still many hidden dangers in the design, operation, and management of existing single-pier bridges. Therefore, this paper takes the K503 + 647.4 separated overpass of the Hegang–Dalian Expressway as the research object and carries out an onsite anti-overturning stability test of a single-column pier bridge. Through loading under various working conditions, the displacement changes of each support are measured, and the reaction changes of the supports are calculated. In the process of simulating the field test using the finite element program ANSYS, a rigid model based on ideal support and an elastic model considering beam deformation are established, and the accuracy of the elastic model is verified by comparison with the field-measured data. Furthermore, a series of parameters, such as the bridge side-span ratio, bridge span number, bearing spacing, loading position, and torsional rigidity, are varied, and finite element simulation is carried out on the basis of the elastic model. Through comparison of the results, a relationship between the parameters of the single-pier bridge and the anti-overturning ability is obtained, which provides a theoretical basis for anti-overturning design research and the effective reinforcement of single-pier bridges.

Research on the Application of Prestressed CFRP in Strengthening Concrete Beams

CFRP plate is a kind of common bridge reinforcement material, its high tensile strength, shrinkage, environmental corrosion resistance. It is conducive to the bridge reinforcement of CFRP plate, which can not only effectively improve the bearing capacity, stiffness, crack resistance and ductility of the component, but also will not increase the original size and weight of the bridge. It has the advantages of reliable anchorage effect, large tensile stress, simple process, good technology and economy. The reinforcement can give full play to the high strength characteristics of CFRP material, effectively improve the mechanical properties of components in the use stage, prevent spalling damage, reduce strain lag phenomenon, while the construction does not interrupt the traffic, and the material utilization rate is high, light weight, beautiful appearance and so on.

Study on Anchoring Effect of Different CFRP Anchors

Prestressed carbon fiber plate (CFRP) is widely used in the field of bridge reinforcement, but the anchoring ways of CFRP are various, and the anchoring performance of different anchoring forms is also different. In this paper, the anchorage performance, failure form and tension control stress of several common anchorage are studied by experiments, the results show that the anchorage effect is the best when the end of the anchor bearing only tension and no other stresses, which can provide some construction guidance for the selection of anchorage in the future.

Application examples of steel-concrete composite bridges that can be quickly replaced

Compared with concrete bridges, steel-concrete composite structure bridges have lighter dead load and lower beam height, which can better adapt to the longitudinal alignment of the route. Therefore, it has great application and promotion value in bridge reinforcement, reconstruction or expansion projects in which the upper structure is removed and the original lower structure is retained. This article introduces the application examples of fast-replaceable steel-concrete composite structure bridges in engineering, and introduces in detail the key contents of the bridge structure, such as structural dimensions, construction methods, and construction periods, which can provide references for the implementation of such projects.

The Interfacial Friction Loss of Prestressed Carbon-Fiber Tendons in a Bending State

Carbon-fiber reinforced plastic (CFRP) is ideal for bridge reinforcement due to its high strength, light weight, and corrosion resistance. Studies on the friction loss of CFRP tendons in a bending state form an important part of advancing the application of CFRP materials to external prestressing strengthening technology. To understand the magnitude and variation of interfacial friction loss of prestressed CFRP tendons under bending conditions, 12 single-bending prestressing tension tests and 4 three-consecutive-bending prestressing tension tests were conducted in this study. Two bending radii of 1.5 m and 2 m, two bending angles of 20° and 30°, and three contact surfaces with different friction coefficients were selected for the steering block condition to measure the friction loss under each stage of tensioning prestress. On this basis, a model for calculating the friction loss rate on the surface of prestressed CFRP tendons was derived for the change of contact stress between CFRP tendons and deflectors during the installation and tensioning stages. The results show that the friction loss of external prestressed CFRP tendons is mainly related to four external factors: bending radius, steering angle, friction coefficient, and the magnitude of tensioning prestress; with the increase of prestress, the friction loss rate goes through three stages, the rising stage, the falling stage, and the stable stage; in the process of friction loss rate change, the main influencing factor controlling the magnitude of friction loss rate changes from bending radius to steering angle. In the theoretical calculation model of friction loss rate, the calculation model of the prestressed CFRP tendons under multiple successive bends can be simplified to a combination of several calculation models for a single bend. This study provides a reference for the engineering field of strengthening reinforced concrete (RC) beams using external prestressed CFRP tendons.

Evaluation of long-service-life cable-stayed bridge strengthening schemes using a two-phase finite element model updating technology

Thus far, the finite element model updating (FEMU) theory has been employed to address parameter errors between finite element models (FEMs) and actual structures. However, previous studies involving multiobjective optimization based on the FEMU of bridges focused on engineering experience or Euclidean distance alone, which affords a less efficient solution with less recognizability. To address this issue, in this work, an innovative two-phase model updating technique was developed to accurately evaluate a long-service-life cable-stayed bridge strengthening scheme. During the first phase, a sensitivity analysis was performed to determine the main updating parameters. Subsequently, the updating process was developed into a multiobjective optimization problem with the establishment of an objective function, which was solved using an improved genetic algorithm (GA). During the second phase, the ELECTRE-III method was introduced to rank the Pareto front from the first stage and determine the final updating results. Additionally, the impact of the mesh sizes of the finite element model (FEM) on the updating process was analyzed. The relative differences between the original numerical results and the elevation measurements reached 20.5 % and 25.0 %, which were then reduced to 11.7 % and 11.9 %, respectively, after the updating process. Results revealed that the updating process considerably improved the accuracy of the FEM. Based on the updated FEM, the structural responses of the Shengli Yellow River Bridge were evaluated in different cable and bolt replacement schemes. Considering construction progress and safety, optimal strengthening schemes were selected and successfully applied to the actual Shengli Yellow River Bridge reinforcement project. This work and its results are expected to serve as a reference for the effective evaluation of long-service-life cable-stayed bridge strengthening schemes.

Seismic risk to beam end corner in railway bridges

The beam end of the railway bridge is the crucial part of the whole bridge, and the earthquake will cause damage to the beam end. In order to ensure the safety of the bridge and track system. To investigate the risk of seismic deformations at the beam end in railway bridges, a three-span continuous rigid frame bridge was taken as a case study and a three-dimensional finite element model of the whole bridge was established in ABAQUS. The deformation angle of the beam end was selected as the damage index, and the seismic vulnerability and risk curves of the beam end were calculated by the incremental dynamic analysis (IDA) method using 22 scaled ground motion time histories. The results show that in the same range of peak ground accelerations (PGAs), the influence of cross-bridge ground motion on the corner deformations of the beam end was much greater than that of the along-bridge ground motion. Under the along-bridge seismic excitation, the damage probabilities for the rotation angles in X, Y and Z-directions did not exceed 50 %. In different damage states, increasing in PGA correlated positively with the beam end damage probability. The vulnerability curves for PGA can be used for the seismic risk assessment of the beam end and can also provide decision support for prioritizing the seismic reinforcement of bridges.