Search Results (17)

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

To compensate the incapability of traditional cable force adjustment methods to automatically optimize cable forces, this paper proposes Midas/Civil and MATLAB as a structure calculator and a cable force optimizer, and external memory as a data transfer. Initial solutions from conventional methods can be optimized by internalizing the influence matrix into the multiobjective particle swarm optimization algorithm with mutation operation and constructing the mathematical model of cable force optimization, and then, a series of Pareto frontier solution sets are obtained. For the first time, fuzzy set theory is introduced for selecting Pareto presolution set for the optimization of cable-stayed bridges, to solve the final reasonable dead load state of bridges. By using this method, the peak vertical displacement of a main girder of the optimized cable-stayed bridge decreased from −11 mm to −6 mm, with a reduction of 45%. Before and after optimization, the difference of peak negative bending moment at the top of the pier was 34.8%, indicating that the main beam was more evenly stressed and the alignment was more reasonable. Full article

This paper presents the results of an experimental dynamic campaign carried out on a reinforced concrete multi-span arch bridge. Five expeditious ambient vibration tests were conducted separately on five spans (one test in each span) of the bridge using only six piezoelectric uniaxial accelerometers. Modal parameters were identified through the well-known Enhanced Frequency Domain Decomposition (EFDD) procedure developed using Matlab R2021b software. At the same time, a finite element model was accurately implemented through a commercial software (Midas Civil) to evaluate the main modal features. A manual model update was successively pursued varying the elastic modulus of the reinforced concrete to make the identified and numerical modes as close as possible. A complete and suitable instrumentation to perform global experimental dynamic tests is not always available. Recursive/Multiple tests have different advantages: handy, easily executable, and could provide a more robust identification thanks to a statical characterization. The paper aims to highlight the peculiarities of recursive/multiple dynamic tests on multi-span arch bridges. The procedure also provides useful suggestions for designing a permanent and continuous vibration-based monitoring system. Full article

Natural vibration characteristics serve as one of the crucial references for bridge monitoring. However, temperature-induced changes in the natural vibration characteristics of bridge structures may exceed the impact of structural damage, thus causing some interference in damage identification. This study analyzed the influence of temperature on the natural vibration characteristics of simply supported beams, which is the most widely used bridge structure. The theoretical formula for the variation of the natural frequency of simply supported beams with temperature was proposed. The elastic modulus of simply supported beams in the range of −40 °C to 60 °C was acquired by means of the falling ball test and the theoretical formula and was compared with the elastic modulus obtained by the three-point bending test at room temperature (20 °C). In addition, the Midas/Civil finite-element simulation was carried out for the natural frequency of simply supported beams at different temperatures. The results showed that temperature was the main factor causing the variation of the natural frequency of simply supported beams. The linear negative correlation between the natural frequency of simply supported beams and their temperature were observed. The natural frequency of simply supported beams decreased by 0.148% for every 1 °C increase. This research contributed to the further understanding of the natural vibration characteristics of simply supported beams under the influence of temperature so as to provide references for natural frequency monitoring and damage identification of beam bridges. Full article

In Korea, a precast floating track with anti-vibration isolators was recently developed to reduce the vibration and noise in urban railway stations, without disrupting train operations. This precast floating slab track is a newly developed structure and differs from existing conventional slab tracks. In this study, a Finite Element Method program (MIDAS CIVIL 2019) was used to analyze the load-carrying ability of structures under the train axle loads. After finishing the design, to understand more precisely about load transfer efficiency of this type of track, an assembly test (two load cases) was conducted with three precast panels (with rail 60 K mounted on) and compared with Finite Element Analysis results. The final results satisfied the test standards in Korea, which confirms that the precast floating track has an acceptable safety factor and structural behavior. Full article

Currently, the seismic designs of reinforced concrete (RC) bridges with tall piers are often accomplished following the ductility-based seismic design method. Though the collapses of the RC bridges with tall piers can be avoided, they are likely to experience major damage and loss of functionality when subjected to strong near-fault ground motions. The objectives of this study are to put forward an innovative design concept of a tall-pier system and its application in tall-pier bridges. The concept of the innovative tall-pier system is derived from the principle of earthquake-resilient structures, and is to improve the seismic performances of the tall-pier bridges under strong near-fault ground motions. The proposed tall-pier system has a box section and is composed of four concrete-filled steel tubular (CFST) columns and energy dissipating mild steel plates (EDMSPs). Trial design of a bridge with the new composite tall-pier system is performed based on a typical continuous rigid frame highway bridge with conventional RC box section tall piers. Both static analysis and nonlinear time history analysis of both the bridges with the new composite tall piers and conventional RC tall piers under the near-fault velocity pulse-type ground motions were conducted in Midas Civil2019 and ABAQUS. The results show that: under the design-based earthquake (DBE), the CFST columns and connecting steel beams remain elastic in the bridge with the new composite tall piers, while the damage is found in the replaceable EDMSPs which help dissipate the seismic input energy. The displacement responses of the new bridge are significantly smaller than those of the conventional bridge under DBE. It is concluded that the bridge with the new composite tall piers is seismic resilient under near-fault ground motions. Full article