Search Results (22)

As urban areas keep growing, there are higher requirements for the carrying capacity of traffic operations, and there are more and more curve incremental launching projects with complex construction conditions. This paper builds upon the walking incremental launching project of a small-curvature steel box girder in Xuchang City and has developed a detailed construction method and monitoring technology. Due to the bridge’s longitudinal gradient being designed as a two-way slope and falling under the category of a small-radius steel box girder, the front end of the main beam exhibits significant lateral deviation, and linear control is difficult. It is necessary to carry out stress and displacement monitoring of the whole process of construction of the curved steel box girder and the guide girder to guide the construction process. The stress conditions of the incremental launching pier and the settlement of the concrete substructure are also studied, and we analyze the stress and displacement characteristics. Firstly, the finite element tool MIDAS Civil is adopted to build a model for the construction. The five most unfavorable working conditions are selected from the entire incremental launch process to analyze the internal force and displacement state of the steel box girder bridge, which is and then compared with the site monitoring value. It is demonstrated by the outcomes that the internal force and deflection of the steel box girder and the guide girder are within the safe construction range, which ensures the security of the incremental launching construction. In the maximum cantilever condition, the guide girder experiences significant stress, but the maximum value is not observed during the maximum cantilever condition of the guide girder. Therefore, whole-process monitoring should be carried during construction to maintain safety measures and quality management. Full article

This study proposes a time-dependent reliability analysis method for aqueduct structures based on concrete carbonation and finite element analysis. The primary goal of this study is to improve the reliability assessment of reinforced concrete aqueducts by incorporating environmental factors such as carbonation over time. First, a three-dimensional finite element model of a reinforced concrete aqueduct is established using the Midas 2022 Civil software, incorporating a time-varying function derived from a predictive model of concrete carbonation depth. Point estimation is then integrated with structural finite element analysis to calculate the first four moments of random variables as functions of concrete carbonation. Additionally, the original performance function is transformed into a normal distribution using dual power transformation and the Jarque–Bera test. The high-order unscented transformation (HUT) is subsequently employed to estimate the first four moments of the transformed performance function, facilitating the calculation of time-varying reliability indices for the carbonated concrete aqueduct. Based on the time-varying reliability index data, a reliability function corresponding to different time points is fitted and applied to service life prediction. The results demonstrate that the proposed method effectively reduces large errors associated with the fourth-moment method in calculating large reliability indices. Furthermore, the comparison with Monte Carlo simulation (MCS) results validates the high efficiency and accuracy of the proposed method, offering a valuable tool for addressing the reliability challenges of aqueducts exposed to carbonation and other environmental factors over time. Full article

Due to prolonged heavy traffic, the Wuhan Changfeng Bridge has experienced extensive cracking in its main girder structure. Of the bridge’s 60 crossbeams, 51 (85%) have developed cracks, while the deck pavement over the steel beams has accumulated a total of 648.8 m of transverse cracks. Additionally, two T-beams exhibit structural vertical cracks of 0.3 mm at the mid-span, exceeding the maximum allowable width of 0.2 mm. This recurrent pavement damage not only compromises driving safety and comfort but also increases maintenance costs. To address these issues, this paper proposes a systematic upgrade plan for the bridge deck system. The plan involves welding additional high transverse beams onto the existing steel transverse beams, removing the original deck slab and replacing it entirely with an orthotropic steel deck. Additionally, two new steel longitudinal beams will be installed. The original simply supported concrete longitudinal beams in the deck will be transformed into an integrally connected continuous steel structure deck system. Using Midas/Civil finite element software, 3D models of Changfeng Bridge, pre and post renovation, were created to analyze the overall dynamic characteristics under five loading scenarios. The ambient vibration test and vehicle field test were conducted to measure the bridge’s natural frequency and impact factor, verifying the dynamic performance and driving comfort of the bridge after the upgrade. The results indicate that the retrofitted bridge experienced a 19.9% increase in overall stiffness. The dynamic performance of the bridge structure was significantly enhanced, and the most notable improvement was observed in dynamic stress, which decreased by 19.4% to 76.9%. Additionally, the steel deck reduced the bridge’s dead load, and the driving comfort on the bridge deck improved. Full article

To address the issue of regional water resource scarcity, water diversion projects have been constructed worldwide. As an essential lifeline project, the prefabricated aqueduct is prevalently utilized in cross-regional water transfer and diversion projects. This paper was based on the prefabricated aqueduct project, which adopted fabricated technologies including the connection technology among the gravity pier, the prefabricated arch ribs, and the prefabricated bent frame columns. The PHC piles, bearing platforms, bent frame columns, arch ribs, and groove bodies were all prefabricated components that were transported to the site for installation. The connections of the prefabricated aqueduct employed to link different components were of such crucial significance that their safety and stability determined whether the overall structure would be compromised. Therefore, the main objective of this paper was to examine the stress and deformation of this prefabricated aqueduct to prevent the occurrence of security risks throughout the entire construction stage. The finite element model was established in Midas Civil, and the entire construction stage was simulated and analyzed. Coupled with on-site monitoring, the stress and deformation of the prefabricated aqueduct were evaluated. The results indicated that the tensile stress, the compressive stress, the vertical displacement, and the lateral displacement of each part of the prefabricated aqueduct met the requirements of the standard, suggesting that the overall structure with the applied connection technology was in a safe and stable state throughout the entire construction stage. Full article

In order to study the effect of temperature on the alignment of a long-span special track bridge, this paper provides a theoretical basis and technical support for bridge design, construction and later operation. This research established the section model of the steel-hybrid beam by COMSOL, and the internal temperature field, transverse temperature, and vertical temperature gradient were analyzed. The Midas Civil bridge model analysis system was established to investigate the influence of temperature difference and temperature gradient on the vertical deformation of the whole bridge. Based on the temperature and displacement monitoring system of the Chongqing Nanjimen track bridge, the temperature and displacement data in 2023 were obtained for comparative analysis. The results show that the temperature field inside the composite beam presents a nonlinear distribution, the daily temperature difference can reach 26.0 °C, and there is a significant temperature gradient between the steel beam and the concrete. The highest temperature is 60.3 °C at 15:00 when the temperature difference between the upper and lower edges of the concrete slab is 11.1 °C, and the daily transverse temperature gradient is 3.2 °C, 5.3 °C and 7.4 °C, respectively. Under the temperature difference in the system, the maximum displacement of the main beam is 92.3 mm, and the mid-span displacement is 132.1 mm under the positive temperature difference. Based on the measured data for the whole year, it is found that the displacement of the main beam under the combined action of ambient temperature and solar radiation significantly exceeds the influence of a single temperature. The research shows that temperature change has an important impact on the stability and durability of the bridge, and temperature monitoring and management should be strengthened in the design and operation stage to ensure the bridge’s safety and smooth operation of the train. Full article

Partially cable-stayed bridges have the characteristics of continuous rigid-frame bridges and cable-stayed bridges, making them a novel composite bridge system. This study focuses on the construction project of a multi-tower high-pier curved partially cable-stayed bridge to investigate the bridge’s stability during construction. The Midas/Civil software was used to establish a model for key construction stages of the bridge, considering structural linear elasticity and geometric nonlinearity. The study examines the impact of static wind loads, asymmetric construction of the main girder, closure sequence, and the load and detachment of the hanging basket on the bridge’s stability during construction. The results indicate that static wind loads have a significant impact on structural geometric nonlinearity, with a maximum reduction of 4.99%. Asymmetric construction at both ends of the main girder can cause structural instability and should be avoided. The geometric nonlinearity stability coefficient for the hanging basket load decreased by 10.83% during the maximum no-cable stage and by 7.84% during the cable stage, significantly affecting the stability during construction. A bridge closure sequence of side-span, secondary midspan, and midspan provides the most stable condition during the construction phase. The results of this study can inform the construction of similar partially cable-stayed bridges. Full article

Under the action of cement hydration heat, the construction environment, thermal insulation measures, and pipe cooling systems, a mass concrete pile cap is subject to a complex internal temperature field, which makes it difficult to control its internal surface temperature difference (T_ISTD), the internal adiabatic temperature rise (T_IATR), and the surface temperature (T_ST). In this study, a mass concrete pile cap of a very large bridge (the length, width, and height were 26.40 m, 20.90 m, and 5.00 m, respectively, and the central-pier pile cap was constructed with C40 concrete) was taken as the research object. The control factors affecting the temperature field of the pile cap were determined by comparing the field temperature measurements with the values calculated with finite element software simulation analysis. By using Midas Civil (2022 v1.2) and Midas FEA (NX 2022) finite element software, these factors (the concrete mold temperature, the concrete surface convection coefficient, the ambient temperature, the pipe cooling system parameters, etc.) were numerically analyzed, and their influence laws and degrees were determined. Full article

The long-span dual-purpose highway-rail double-tower cable-stayed bridge has the characteristics of a large span and large load-bearing capacity. Compared with the traditional cable-stayed bridge, its wind resistance and seismic resistance are weaker, and the dynamic characteristics of the bridge are closely related to the wind resistance and seismic bearing capacity of the bridge. This study investigated the influence of the variations of bridge member parameters on the dynamic characteristics of the bridge and then improved the dynamic characteristics of the bridge. To provide the necessary experimental theory for the research work of the long-span dual-purpose highway-rail double-tower cable-stayed bridges, this paper takes the world’s longest span of the dual-purpose highway-rail double-tower cable-stayed bridge as the background, using the finite element analysis software Midas Civil 2022 v1.2 to establish a three-dimensional model of the whole bridge by changing the steel truss beam stiffness, cable stiffness, pylon stiffness, and auxiliary pier position, as well as study the influence of parameter changes on the dynamic characteristics of the bridge. The results show that the dynamic characteristics of the bridge can be enhanced by increasing the stiffness of the steel truss beam, the cable, and the tower. The stiffness of the steel truss beam mainly affects the transverse bending stiffness and flexural coupling stiffness of the bridge. The influence of cable stiffness is weak. The tower stiffness can comprehensively affect the flexural stiffness and torsional stiffness of the bridge. The position of auxiliary piers should be determined comprehensively according to the site conditions. In practical engineering, the stiffness of components can be enhanced according to the weak links of bridges to improve the dynamic characteristics of bridges and save costs. Full article

Box culverts, as a commonly employed structural form for culverts, play a critical role in traversing topographic barriers, ensuring the safety and smooth operation of transportation means such as roads and railways. However, traditional design methodologies are often time-consuming and prone to inaccuracies, failing to achieve the efficiency and precision required by modern engineering construction. To address these challenges, using the Revit 2021 and Midas Civil 2021 software platforms, we developed a Building Information Modeling (BIM) parametric modeling method for box culverts using Dynamo’s visual programming capabilities. This method enables the rapid and accurate automated generation of box culvert BIM models. Furthermore, this study proposes an effective strategy for conversion between box culvert BIM models and Midas Civil finite element models, as well as internal force visualization within a BIM project. A case study involving a box culvert underpass beneath an expressway in an urban setting was modeled parametrically and structurally validated, demonstrating that the approach not only significantly enhances modeling efficiency but also strengthens computational capabilities through bidirectional data exchange between BIM and Finite Element Analysis (FEA) software. This research has effectively advanced the application and practical implementation of BIM technology in box culvert engineering. Full article

Bridges often improve the visual appeal of urban landscapes by incorporating curve elements to create iconic forms. However, it is noteworthy that curved bridges have unique mechanical properties under loads compared to straight bridges. This study analyzes a spatial three-curved steel box girder bridge based on an actual engineering case with a complex configuration. Initially, the finite element software Midas/Civil 2021 is utilized to establish a beam element model and a plate element model to examine the structural responses under dead loads in detail. Then, two different temperature gradient distribution models are employed for the temperature effect analysis. The backpropagation neural network (BPNN) optimized by the WOA algorithm is trained as a surrogate model for finite element models based on the results of temperature stress simulation. The results reveal that the bending–torsion coupling effect in the second span of the spatial three-curved steel box girder bridge is pronounced, with the maximum torque reaching 40% of the bending moment. The uneven distribution of cross-section stress is particularly significant at the vertices, where the shear lag coefficient exceeds 3. Under the action of temperature gradients, the bridge displays a warped stress state; the stress results obtained from the exponential model exhibit a 21% increase compared to BS-5400. Optimization of the weights by the WOA algorithm results in a significant improvement in prediction accuracy, and the convergence speed is improved by 30%. The coefficient of determination (R²) for predicting temperature stress can reach as high as 0.99. Full article

To facilitate the first application of the novel concrete-filled built-up K-joints with different brace sections in truss bridges, the present paper aims to determine their practicability through a comparison with integral joints. First, a structural analysis was carried out using the MIDAS CIVIL software to evaluate the loading applied to the structure. Additionally, boundary condition analysis was carried out. After that, the symmetric multi-planar joints were developed, using Abaqus 6.14 for the strength verification and the failure mode identification. These were followed by the multi-planar joints estimate cost. The results indicated that for positive bending, the novel joint deformed by 2.01 mm, compared to 4.83 mm for the integral joint in the serviceability limit state. These deformations were equal to 5.58 mm and 7.68 mm, respectively, in the negative bending. Verification under the ultimate limit state indicated a deformation of 10.43 mm for the novel joint type and 16.59 mm for the integral joint in the positive bending, whereas deformations of 15.89 mm and 16.82 mm were indicated in the negative bending. Moreover, a failure mode analysis showed a buckling of the arc yielding for the novel joint type and a buckling of the gusset plate for the integral joint. Finally, the results showed that the novel type of joint was more expensive by about CNY 111,286.06. Full article

In consideration of the mild climatic conditions of North Vietnam with average monthly air temperatures ranging from 15 °C in winter to 26.5 °C, this study analyzes the regulation of the temperature regime and thermally stressed state of a concrete gravity dam made of rolled concrete. Despite the favorable weather conditions, there remains a risk of thermal cracking, necessitating the presentation of crack-formation models from different countries to assess and mitigate the risk of cracking through the adjustment of construction conditions. The study has developed a predictive model for the temperature regime and thermally stressed state of a layer-by-layer concrete mass under the given construction conditions using the factor-analysis method. Regression equations were then derived from the factorial experiment to quantify the responses of the maximum temperature and maximum stress in the concrete mass. The numerical finite-element method using the Midas Civil software package was employed to calculate the temperature regime and thermally stressed state of the concrete mass. To validate the mathematical predictive model, it was tested on the Ban Lai gravity dam in North Vietnam. The dam, which was constructed from rolled concrete and stands 56 m tall, was selected as the object in this practical example. The results obtained from applying the predictive model were compared to the results obtained from numerical calculations of the dam under construction, as well as the findings from field observations. These results were found to be in good agreement, indicating the effectiveness of the predictive model. Furthermore, an evaluation of the potential for temperature cracking of the concrete during the construction period was conducted. Full article

Tied steel box arch bridges are increasingly being used due to their attractive appearance, high load-bearing capacity, and good stress performance. Their construction involves multiple processes and factors. Construction monitoring can ensure that such a bridge remains in its intended stress and linear states during and after construction. This helps to minimize deviations from the design state at every stage of construction. Using the segmental assembly construction technique, this study conducted construction monitoring of the alignment and force at each stage of the reconstruction of bridges using MIDAS Civil software. The construction monitoring analysis indicated that the arch rib and lattice beam were correctly placed, thereby meeting the specified requirements for arch rib closure. Displacement errors between the measured and theoretical values at each stage of construction fell within an allowable range, resulting in overall smooth bridge alignment. The measured stress in the main arch and the lattice beam generally corresponded to the theoretical stress derived from the control section stress of the entire bridge. The deviation between the cable force of the suspender and the tie rod and theoretical value fell within 10%, indicating good stress reserve. The symmetrical monitoring points in the analyzed rigid-frame tied steel box arch bridges exhibited symmetrical displacement, stress, and cable force results under various working conditions. This observation further confirms the effectiveness of construction monitoring using the segmental assembly technique. Full article

To investigate the reasonable range of the inclination angle of arch ribs, a spatial finite element method was employed based on a concrete-filled steel tube (CFST) basket-handle through an arch bridge with a span of 360 m. A spatial finite element model was established using Midas/Civil software, which was verified with actual bridge data. The effects of different arch rib inclination angles were investigated under static loads. The structural natural frequencies, linear elastic stability coefficients, internal forces, and displacements were comprehensively considered to determine the reasonable range of the inclination angle. The results show that when the inclination angle ranges between 8° and 10°, the first, third, and sixth natural frequencies of the structure are increased. It effectively improves the lateral and torsional stiffness of the arch ribs while ensuring optimal out-of-plane stability of the arch ribs. Compared with the parallel arch, the stability is improved by 20.2%. The effects of angle variation on displacement and internal force of the arch ribs were not significant. Considering all indicators, the optimal range of the inclination angle for the arch ribs of 300-m-level highway CFST arch bridges is suggested to be 8~10°. Full article

Because of their beautiful appearance, strong crossing ability, and reasonable stress performance, the application of tied steel box arch bridges is becoming more and more extensive. Bridge construction monitoring can control and adjust the deviation state to ensure the stress and linear state of the bridge after completion. This study carried out a symmetrical construction monitoring analysis and completed state evaluation of the newly built Dafeng River Bridge in Guangxi Province based on the finite element method. MIDAS Civil finite element software is used for simulation analysis to calculate the deformation and stress of the tied steel box arch bridge at the construction and completion stages. The tensile and compressive stress of the main arch and transverse brace, as well as the cumulative displacements of the main arch and lattice beam, are symmetrically distributed. The maximum tensile and compressive stresses are 15.1 MPa and 74.6 MPa, respectively, less than the specification’s allowable value. Meanwhile, for the completed bridge under the loading combinations of serviceability limit state and bearing capacity ultimate limit state, the stress of the main arch, transverse brace, and lattice beam meets the specification requirements. The maximum cable forces of the suspender and tie rod under the bearing capacity ultimate limit state are 2189.4 kN and 2991.2 kN, and their corresponding minimum safety factors are 3.2 and 2.7. In addition, the deviations between the on-site monitoring and the finite element theoretical values are within the specification allowable range for the cable force of the suspender and tie rod and the bridge deck alignment. It indicates that the bridge construction monitoring effect is reasonable and ideal, and the symmetrically finite element simulation analysis can provide a theoretical basis for construction monitoring. Full article