Construction control of cable-supported bridges requires reliable vibration-based refined cable-tension identification, yet its accuracy is often limited by uncertain elastic end restraints that are difficult to quantify in practice. This study presents a modal-data-driven framework for refined cable-tension evaluation under uncertain boundary conditions. The framework combines a finite-element forward model with two coupled inverse modules: equivalent boundary-stiffness identification and cable-tension inversion. A Monotone–Bracketing Newton scheme is developed for tension inversion, integrating bracketing, MAC-based modal-branch locking, and sensitivity-driven Newton updates. Boundary stiffness is identified by optimizing non-dimensionalized variables through a tailored covariance matrix adaptation evolution strategy using a joint objective based on frequency residuals. Numerical studies on 50 cables show that, when cable tension is estimated using the 100 identified sets of equivalent boundary stiffnesses, the 95th-percentile error is 5.59 × 10 −4 . Laboratory strand tests under three unknown boundary conditions yield tension errors mostly within 0.5%, with a maximum of 0.92%. An in-construction cable-stayed bridge case further demonstrates practical applicability, with tension errors within 1% for instrumented cables, stage-wise tension differences mostly within 2%, and a maximum main-girder vertical alignment deviation of about 5 cm. The results demonstrate that the proposed framework provides an effective and practical approach for vibration-based refined evaluation of cable tension in the presence of boundary uncertainty.

Accurate detection of anomalies in bridge monitoring data is crucial for structural health monitoring systems. However, the limited availability of labeled data and the imbalanced distribution of anomaly categories pose significant challenges to conventional supervised learning approaches. This study proposes a semi-supervised anomaly detection framework that integrates pseudo-label enhancement with dynamic loss adjustment to address these issues. Multiple sub-models are constructed using an undersampling strategy, and high-confidence pseudo-labels are generated via consistency voting, effectively augmenting anomaly class training data while reducing manual labeling efforts. A novel CoFocus Ramp Loss function—incorporating class weights, a focusing parameter, and a dynamic coordination factor—is introduced to modulate the model’s attention across various classes and label sources during training, improving the recognition of anomaly classes. Experimental results on the acceleration monitoring dataset from the Hardanger Bridge demonstrate that the proposed method substantially enhances anomaly detection performance while maintaining high accuracy for normal samples, achieving an overall accuracy of 97.75%. Feature maps and Grad-CAM visualizations further reveal that the model follows a hierarchical perceptual process, progressively refining its focus from shallow to deep semantic levels. In the decision-making layers, it exhibits distinct spatial attention regions for different classes. In summary, the proposed semi-supervised anomaly detection framework delivers high precision and robust identification of structural anomalies under class-imbalanced conditions, without relying on extensive labeled data. These results highlight its practical value for engineering applications facing the challenges of imbalanced anomaly detection. Future work will extend the framework to multi-source heterogeneous sensor data to enhance adaptability in complex operational environments.

Monitoring and controlling temporary transverse braces and accurately predicting their stresses are critical to construction safety in cable-stayed tower works. This study establishes a monitoring-and-modeling framework and evaluates it on the A-shaped tower of the Songzihe Grand Bridge. Construction-stage stress measurements are acquired for the braces, and two finite-element (FE) representations are formulated: a 3D solid model and a computationally efficient beam model. To enhance predictive fidelity for the beam representation, an equivalent rotational stiffness of the brace–tower connection is derived from structural mechanics and embedded as optimized boundary conditions. Both FE models are calibrated and validated against full-scale construction data; predictive accuracy and computational cost are then compared. Results indicate that beam models with idealized pinned or fixed ends exhibit inferior stress predictions relative to the solid-model reference, whereas the optimized beam model reproduces brace stress, bending moment, and deflection with high fidelity. Its overall stress deviation is only 1.42 MPa higher than that of the solid model while requiring 4.4

Despite anchor span tension adjustment in an unloaded cable state constituting a critical phase of suspension bridge construction, comprehensive theoretical guidance on this topic remains lacking. This study proposes a strand tension calculation method based on the physical system of tangency point migration in unsupported strand segments, catenary configuration evolution, and unstressed length variations during splay saddle rotation for arbitrary splay saddle deflection angles. The coupling mechanism between saddle rotation and tension adjustment is simulated through a moment equilibrium model established for splay saddles without temporary constraints. This model enables controlled rotation from actual to theoretical saddle positions through tie rod length adjustments while ensuring uniform anchor span tension distribution in the completed bridge state. Finally, an algorithmic framework for tension adjustment is established. This framework resolves large-scale optimisation challenges in tie rod length determination by implementing the limited-memory Broyden-Fletcher-Goldfarb-Shanno bound algorithm. The application of this methodology in the construction of the Yongren Bridge reduced the splay saddle deflection angle error in the unloaded cable state from 0.068 degrees to 0.001 degrees, with 92.9 % of the strand tensions in the completed bridge state exhibiting relative deviations below 3 %. These results confirm the superior performance of the proposed approach over that of conventional methods, thereby offering a reliable methodology for high-precision tension adjustment in suspension bridge engineering.

The precise placement of bridge caissons in fast-moving currents poses particular difficulties due to the occurrence of vortex shedding from these typically bluff structures leading to significant side-to-side oscillations. In this paper, we report on computations performed in order to recommend to a structural engineering team two practical adaptations to their caisson design in order to reduce the impact of vortex shedding from it. The adaptations involve the rounding of the sharp corners of the original caisson design together with the installation of a splitter plate of a suitable length at its base. The rounding of the corners reduces the available working space inside the caisson and this imposes a constraint on the process of finding the optimal dimensions of the proposed adaptations to yield worthwhile benefits at acceptable cost. The Unsteady Reynolds-Averaged Navier-Stokes (URANS) computational approach was used. Discretization was with second-order accurate spatial and temporal schemes while the effects of turbulence were accounted for with a turbulence model that has been extensively validated in benchmark flows with vortex shedding. The recommended adaptations were integrated in the caisson's final design and were implemented in the field. In situ velocity measurements obtained using a current meter mounted on a vessel, and photographic observations obtained from a drone provided a rare opportunity to validate the computations, and a clear demonstration of the efficacy of the proposed flow-control measures.

Caissons are important platforms and prerequisites for the smooth construction of deep-water bridges.Hydrodynamic loads are key factors affecting the precise positioning,sinking,and landing of the caisson in its segmental construction.To reduce the hydrodynamic load of steel caissons under current loads,this paper proposes a restrain method for rectangular steel caissons by adding a certain length of splitter plate at the rear end.First,a two-dimensional simplified model of a steel caisson was established based on the open source analysis platform OpenFOAM using the computational fluid dynamics method.A modified k-ε model was introduced to solve the Navier-Stokes equation of the steel caisson under ultra-high Reynolds numbers.The accuracy of the proposed method was verified using square and rectangular cross-section bluff columns.Subsequently,based on the full-scale steel caisson model,the influence of splitter plate setting on the hydrodynamic drag and lateral fluctuation force of the steel caisson was analyzed,and the inhibition effect of different lengths of the splitter plate and front/back end splitter on hydrodynamic load was clarified.An optimized and feasible splitter plate setting scheme is proposed.The results show that the standard k-ε model cannot accurately capture the vortex shedding process of square and rectangular bluff bodies at high Reynolds numbers,and the hydrodynamic load would be significantly underestimated.The modified k-ε model can accurately simulate the flow characteristics of a rectangular bluff body,which is in good agreement with the experimental data,and can be used to calculate and analyze steel caissons.The rectangular steel caisson with rounded corners can effectively reduce the hydrodynamic drag and lateral swing amplitude but increase the swing frequency.Adding a central splitter plate at the rear end of the steel caisson can significantly reduce the hydrodynamic drag and lateral swing force.When the length of the splitter is within 1/10 of the longitudinal length of the steel caisson,the inhibition effect is the highest.When the length of the splitter plate is more than 0.75 times the longitudinal length of the steel caisson,the wake begins to oscillate,which results in an increase in the lateral swing force;adding a front splitter can restrain such an increase.The effect of the front splitter on the hydrodynamic action can be ignored.A field flow trace test verified that the formation of the wake vortex can be reduced and delayed using rear-end splitter plates,and the hydrodynamic drag and lift loads of a steel caisson can be effectively restrained.

The paper reports on the computation of the hydrodynamic loads on a full-scale caisson at high Reynolds number in the presence of vortex shedding. The objective was to obtain reliable predictions of the resulting mean and fluctuating forces to guide the design of an actual caisson in the absence of relevant experimental data. A further objective was to investigate the effectiveness of alternative methods for the control of vortex shedding that can be implemented in practice. Two such methods were evaluated: (1) by rounding the corners of the rectangular-sectioned caisson, and (2) by the placement of a splitter plate in the separated wake region. The computations, which were performed using the OpenFOAM open-source software, were for a fixed caisson and hence did not account for motions due to vortex-induced vibrations. The effects of turbulence were accounted for by performing large-eddy simulations, and by using two-equation eddy-viscosity closures, one of which was specifically adapted to account for the interactions between the periodic vortex shedding and the random turbulence. The numerical accuracy was checked using the grid convergence index method, and the computations were extensively validated against data from relevant benchmark flows. The recommendations of this research were implemented in the design of a full-scale caisson that has since been deployed in a bridge construction project.

For the bridge tower with large inclination angle, the beam element in Midas finite element software is used to model and analyze the bridge tower structure, and its accuracy is difficult to guarantee. In this paper, taking the construction of a suspension bridge’s inward-inclined tower as the research background, the finite element simulation of the inward-inclined bridge tower is carried out by using the two modeling methods of the beam element and the solid element. The calculation accuracy of the beam element model, the specific position and the jacking force applied by the active transverse brace of the inward-inclined bridge tower are determined, and the field test of the tower bottom stress during the construction process is performed. The results show that: when the inclination angle of the bridge tower is small (5 °), the beam element element is used for modeling and analysis, which has fast calculation speed and high calculation accuracy; When the inclination angle is 15 °, the error of the beam element model exceeds 30%, and it is recommended to use the solid model for calculation; the active cross brace plays a key role in controlling the stress at the bottom of the tower column before the lower cross beam is applied. And after the construction of the cross beam, the active cross brace forms a closed frame structure with the lower tower column, and the subsequent cross brace has little impact on the stress at the bottom of the tower column; Compared with increasing the number of temporary cross braces, increasing the jacking force can improve the stress at the bottom of the tower. And by adjusting the position of the active cross brace and applying the appropriate active jacking force, the stress at the root of the tower column can be greatly improved.

A high precision back propagation neural network-particle swarm optimization (BP-PSO) algorithm inversion method is proposed to calibrate the microparameters of the clustered-particle logic concrete discrete element method model. The calibration targets include initial damage, failure mode, and mechanical properties of the material. The research utilise 243 training datasets generated through orthogonal experimental design and conducted simulations to train the BP neural network. In addition, a parameter sensitivity analysis is employed on the trained BP neural network to quantify the impact level of each microparameter and guide future macroparameter fine-tuning. The results indicate that the mean absolute percentage error of the BP-PSO inversion method is only 3.79%. This research also study on the concrete failure mechanism by using a mesoscale model based on clustered-particle logic, which considered concrete as a three-phase composite composed of mortar matrix, aggregates, and interfacial transition zone. The crack initiation, propagation and coalescence of DEM model show a good agreement with the experimental results.

通过PFC2D建立考虑骨料级配的钢筋混凝土梁离散元细观数值模型,开展钢筋混凝土梁极限承载力的研究.混凝土标准棱柱单轴压缩模拟验证了混凝土单元细观参数的准确性.通过修改平行黏结模型获得了适用于钢筋模拟的平行.强化黏结接触模型,钢筋单轴拉伸模拟验证了钢筋单元细观参数的准确性.建立了无缺口钢筋混凝土梁离散元数值模型,在此基础上生成预制缺口钢筋混凝土梁数值模型,根据缺口位置及倾角分为9种工况,分析了各工况下梁的裂缝扩展规律及极限承载力.结果表明:缺口位置对裂缝的扩展过程影响较大,一般起裂位置均位于缺口顶端;缺口倾角仅对裂缝扩展初期有影响,后期裂缝依然会沿竖向发展;缺口梁极限承载力约为无缺口梁极限承载力的95％～98％.

This paper improves the method of high-efficiency calibrating the meso-parameters considering the concrete aggregate gradation, and carries out numerical simulations of four-point bending strength test and direct shear strength test on concrete beams. Firstly, unconfined uniaxial compression test carried out to calibrate the meso-parameters of C40 concrete based on DEM. Secondly, the accuracy of the numerical model is verified according to the stress-strain curve and failure morphology of concrete prism. Finally, the crack propagation and load-displacement curves of concrete beams under four-point bending strength test and direct shear strength test were analyzed. The result show as follow: ① The DEM numerical model which take into account the concrete as a three-phase composite material can well realize the mechanical property of concrete. The display of force chains and micro-cracks greatly contributes to the concrete failure mechanism. ② The numerical model is generated by the random distribution of particles, which shows the characteristics of concrete heterogeneity, and defines the contact model between particles with parallel bond model (PBM). Compared with the numerical simulation and experiment results, the error is within 10.4%; ③ In four-point bending strength test, the crack initiates from the bottom edge of the beam and propagates upward. With the increase and coalescence of micro-cracks, only one concentrated, wide and long macro-crack is formed; In direct shear strength test, however, the high shear stress of two shear surfaces resulted in the generation of cracks. With the one side crack coalescence, the other side of crack initiate follow, and finally two coalescence macro-cracks are formed.

为研究双折线抗力模型对空爆荷载梁式构件振动位移的影响,提出了柔性、刚性两类梁式构件正向弹塑性振动及回弹阶段弹塑性振动的分析法.应用等效单自由度法建立了各阶段振动方程并依据不同的初始条件推导出了各阶段的理论解.采用此理论解和代表性塑性强化系数,开展了双折线抗力模型中不同塑性强化程度对两类梁式构件正向弹塑性振动及回弹阶段弹塑性振动位移的典型工况验证.研究结果表明:基于双折线抗力模型位移理论解的适用范围更广;随着双折线抗力模型塑性强化系数的增大,两类梁式构件的最大弹塑性位移、残余变形均逐渐减小,且残余变形降低程度高于最大弹塑性位移;塑性强化系数增大到一定程度,梁式构件回弹阶段将出现塑性振动位移,进一步降低残余变形,无塑性回弹位移的理想弹塑性抗力模型会高估空爆荷载下梁式构件的残余变形.

In order to study the load limiting method of long-span concrete truss composite arch bridge at low temperature, the finite element analysis of the operating force of a 138m truss composite arch bridge at low temperature was firstly carried out, including the deflection change and stress distribution caused by temperature. Secondly, the load characteristics of trucks on the bridge are analyzed and the lower limit load is analyzed based on WIM data. Finally, the analysis results show that the long-term deformation of the truss composite arch bridge under the action of temperature is m-shaped, and the structure has a large tensile stress at the junction of empty and solid sides in the middle of span and at the lower chord position at the double columns. This kind of bridge is very sensitive to the effect of temperature. The influence of vehicle load on the structure under low temperature should be paid attention to and the relevant load limiting method is proposed to provide reference for this kind of bridge.

某大桥为两联六跨刚架拱桥,采用增大截面法加固.针对加固过程的安全性,采用Midas Civil对4种加固施工方案进行比选;采用有限元模型对混凝土裂缝出现较多的实腹段进行结合面收缩应力分析.研究结果表明:“实腹段-拱腿-斜撑-弦杆”的施工顺序能有效控制拱脚及小节点应力,减缩剂可减少跨中底缘37.7％的收缩拉应力.背景桥梁采用优化方案施工后,受力良好,混凝土裂缝得到有效控制,可为同类桥梁加固施工提供参考.

Through decades of operation, deformation fluctuation becomes a central problem affecting the normal operating of concrete truss combination arch bridge. In order to clarify the mechanism of temperature-induced deformation and its impact on structural stress distribution, this article reports on the temperature distribution and its effect on the deformation of concrete truss combination arch bridge based on bridge health monitoring on a proto bridge with 138 m main span. The temperature distribution and deformation characteristics of the bridge structure in deep valley area are studied. Both of the daily and yearly temperature variation and structural deformation are studied based on bridge health monitoring. Using the outcome of monitoring data, three-dimensional solid finite element models are established to analyze the mechanism of temperature-induced deformation of the whole bridge under different temperature fields. The influence of temperature-induced effect is discussed on local damage based on the damage observation of the background bridge. The outcome of comparisons with field observation validates the analysis results. The relevant monitoring and simulation result can be referenced for the design and evaluation of similar bridges.

The purpose of this paper is to report on the development of a three-dimensional (3D) creep calculation method suited for use in analyzing long-term deformation of long-span concrete girder bridges. Based on linear creep and the superposition principle, the proposed method can consider both shear creep and segmental multiage concrete effect, and a related program is developed. The effects of shear creep are introduced by applying this method to a continuous girder bridge with a main span of 100 m. Comparisons obtained with the nonshear case show that shear creep causes long-term deformation to increase by 12.5%. Furthermore, the effect of shear creep is proportional to the shear creep coefficient; for a bridge with different degrees of prestress, the influence of shear creep is close. Combined with the analysis of a continuous rigid bridge with a main span of 270 m, the results based on the general frame program suggest that shear creep amplification is multiplied by a factor of 1.13–1.15 in terms of long-term deformation. Moreover, the vertical prestress has little effect on shear creep and long-term deformation. The 3D creep analysis shows a larger long-term prestress loss for vertical prestress at a region near the pier cross section. The relevant computation method and result can be referenced for the design and long-term deformation analysis of similar bridges.

为研究大跨径混凝土梁桥在长期变形分析时剪切徐变的影响,针对剪切徐变系数的取值问题,提出一种基于扭转的剪切徐变试验装置和测试方法,并开展三组混凝土试件的剪切徐变试验研究;获取375 d的徐变系数曲线,利用现行规范模型的参数修正,对剪切徐变的发展规律进行分析,并通过有限元对结果进行验证,研究结果表明:基于扭转的剪切徐变试验装置可对构件进行有效加载;通过扭转剪切得到的徐变系数计算公式可用于试验数据分析;C30混凝土试验剪切徐变终极值为规范轴压徐变终极值的2.26～2.63倍,剪切徐变在受荷早期的发展低于轴压徐变,但后期逐步加速;受扭构件等剪切影响显著的结构徐变计算应考虑剪切徐变效应.

With the development of economy, highways play an important role in transportation system, especially for heavy highways. In order to learn traffic flow characterizes of heavy highway on rainy days, this study focuses on a heavy highway, Xuanda Highway, in Hebei Province. The research selects traffic data of seven days, collected by weigh-in-motion (WIM) system at Haierwa Bridge, to analyse the effect of rain on traffic flow characterizes, including volumes and speed. Specific issues evaluated that the traffic volumes were not sensitive to little rain, while speed of each time period has different degree of reduction during rainy days. The research further indicates people’s willingness to travel. In addition, the study quantifies the speed characteristics for each class, and the relationship between speed and heavy vehicle ratio on rainy days. 

针对分丝管索塔锚固区受力状态问题,以南盘江特大桥(108 m+180 m+108 m三跨矮塔斜拉桥)为背景,进行锚固区混凝土劈裂行为与受力机理研究.首先,综合考虑拉索对索鞍的压力和摩擦力作用,推导拉索沿纵桥向的压力分布公式;然后,建立ABAQUS实体模型并按压力分布公式加载,分析其空间应力分布规律.最后,开展锚固区节段足尺模型试验,采用自平衡反力梁法,分四级张拉斜拉索,最大张拉力为1.09倍设计张拉力,观测并验证锚下混凝土的受力特征.研究结果表明:作用在鞍下混凝土上的压力受摩擦力影响较小,沿纵桥向基本服从均匀分布;锚固区混凝土压应力及拉应力均低于规范限值要求,处于安全工作状态;设计荷载作用下,最大劈裂应力出现在两分丝管索鞍之间的混凝土部分,但应力水平较小,此外两索鞍两侧及与索鞍接触的混凝土区域亦出现较小劈裂应力;索鞍底缘附近的混凝土劈裂应力沿竖向衰减迅速,劈裂应力沿竖向的叠加效应不明显.有限元模型显示,当拉索索力达到25 100 kN时,锚固区混凝土达到劈裂极限应力而开裂;在横桥向,竖向压应力由核心区域向两侧逐渐减小,近似成二次抛物线分布;有限元模型应力分布计算结果与模型试验实测结果基本一致,具有可靠性.

The effective thermal conductivity (ETC) of concrete is the most important parameter in determining the temperature field and thermal stresses. A 2D random polygonal aggregate model and its modified model considering porosity were established in this paper in order to partially replace the experiment for parametric analysis on the ETC of concrete and to save the experiment cost. A mesoscopic finite element method for the ETC of concrete with arbitrary gradation was also proposed. In addition, the influence factors (thermal conductivity of coarse aggregate, cement mortar, and volume fraction of coarse aggregate) of the effective thermal conductivity of concrete were analyzed. The results show that the 2D gradation curve of coarse aggregates is proved to exist, and there is a corresponding relationship between the 2D and 3D gradation curves of coarse aggregates. The effective thermal conductivity of concrete has a positive exponential relationship with the volume fraction of coarse aggregates, a positive logarithm relationship with the thermal conductivity of coarse aggregates, and a positive linear correlation with the thermal conductivity of cement mortar. The most practical way to improve the effective thermal conductivity of concrete is to increase the ETC of the cement mortar, but the most effective way is to replace the aggregate with a material with a high thermal conductivity.