Search Results (130)

During the construction of large-span steel truss arch bridges, challenges such as complex control calculations, frequent adjustments of the cantilever structure, and deviations in the closure state often arise in the process of the assembly and closure of arch ribs. Based on the stress-free state control theory, this paper proposes a precise assembly control method for steel truss arch bridges, which takes the minimization of structural deformation energy and the maintenance of the stress-free dimensions of the closure wedge as the control objectives. By establishing a mathematical relationship between temporary buckle cables and the spatial position of the closure section, as well as adopting the influence matrix method and the quadprog function to determine the optimal parameters of temporary buckle cables (i.e., size, position, and orientation) conforming to actual construction constraints, the automatic approaching of bridge alignment to the target alignment can be achieved. Combined with the practical engineering case of Muping Xiangjiang River Bridge, a numerical calculation study of the precise assembly and closure of steel truss arch bridges was conducted. The calculated results demonstrate that, under the specified construction scheme, the proposed method can determine the optimal combination for temporary buckle cable tension. Considering the actual construction risk and the economic cost, the precise matching of closure joints can be achieved by selectively trimming the size of the closure wedge by a minimal amount. The calculated maximum stress of the structural rods in the construction process is 42% of the allowable value of steel, verifying the feasibility and practicality of the proposed method. The precise assembly method of steel truss arch bridges based on stress-free state control can significantly provide guidance and reference for the design and construction of bridges of this type. Full article

Asynchronous-pouring construction (APC) technology employs a suspended hanging basket directly supported by corrugated steel webs (CSWs) with high shear strength, significantly enhancing construction efficiency. To further elucidate the characteristics of APC and promote its application in prestressed concrete (PC) composite box girder bridges with CSWs, this study analyzes the sustainable development of APC from two aspects, including environmental impact and economic performance. Finite element models of APC and traditional balanced cantilever construction (TBCC) were established for the case bridge with a main span of 105 m. The stress distribution and deflection of the main girder in the cantilever construction state are compared with field measurements, and the variations in stress and deflection in typical sections during construction are analyzed. Additionally, a simplified theoretical method is proposed for calculating stress and deflection in PC composite girder bridges during the cantilever construction stage using APC. Results demonstrate that APC demonstrates significant advantages in reducing economic costs and minimizing long-term environmental impacts. Furthermore, this method ensures acceptable stress and deflection throughout construction. The proposed simplified formula for CSW deflection in the maximum segment agrees well with both measured data and finite element results, providing a valuable reference for deflection calculation in APC applications. Full article

This study addresses the water basin effect in the underwater sand layer of steel pipe pile cofferdams by integrating the concept from building foundation pits to cofferdam foundation pit analysis. A theoretical derivation is presented for the deformation evolution of steel pipe piles and bottom seals within the cofferdam pit. The cofferdam construction dewatering process is divided into four stages: riverbed excavation for bottom sealing, dewatering to the second support, dewatering to the third support, and dewatering to final bottom sealing. The steel pipe piles are modeled as single-span or multi-span cantilever continuous beam structures. Using the superposition principle, deformation evolution equations for these statically indeterminate structures across the four stages are derived. The bottom seal is simplified to a single-span end-fixed beam, and its deflection curve equation under uniform load and end-fixed additional load is obtained via the same principle. A case study based on the 6# pier steel pipe pile cofferdam of Xi’an Metro Line 10 Jingwei Bridge rail-road project employs FLAC3D for hydrological–mechanical coupling analysis of the entire dewatering process to validate the water basin effect. Results reveal a unique water basin effect in cofferdam foundation pits. Consistent horizontal deformation patterns of steel pipe piles occur across all working conditions, with maximum horizontal displacement (20.72 mm) observed at 14 m below the pile top during main pier construction completion. Close agreements are found among theoretical, numerical, and monitored deformation results for both steel pipe piles and bottom seals. Proper utilization of the formed water basin effect can effectively enhance cofferdam stability. These findings offer insights for similar engineering applications. Full article

This study aims to establish a methodology that integrates experimental measurements with finite element analysis (FEA) to investigate the mechanical behavior and dynamic characteristics of soft–hard laminated composites fabricated via additive manufacturing (AM) under dynamic excitation. A hybrid AM technique was employed, using the PolyJet process based on stereolithography (SLA) to fabricate composite beam structures composed of alternating soft and hard materials. Initially, impact tests using a steel ball on cantilever beams made of hard material were conducted to inversely calculate the first natural frequency via time–frequency analysis, thereby identifying Young’s modulus and Poisson’s ratio. For the viscoelastic soft material, tensile and stress relaxation tests were performed to construct a Generalized Maxwell Model, from which the Prony series parameters were derived. Subsequently, symmetric and asymmetric multilayer composite beams were fabricated and subjected to impact testing. The experimental results were compared with FEA simulations to evaluate the accuracy and validity of the identified material parameters of different structural configurations under vibration modes. The research focuses on the time- and frequency-dependent stiffness response of the composite by hard and soft materials and integrating this behavior into structural dynamic simulations. The specific objectives of the study include (1) establishing the Prony series parameters for the soft material integrated with hard material and implementing them in the FE model, (2) validating the accuracy of resonant frequencies and dynamic responses through combined experimental and simulation, (3) analyzing the influence of composite material symmetry and thickness ratio on dynamic modals, and (4) comparing simulation results with experimental measurements to assess the reliability and accuracy of the proposed modeling framework. Full article

Ground-based movable roof construction offers advantages such as flexible adjustment, energy conservation, environmental protection, improved comfort, structural stability, and high space utilization. However, it faces technical challenges such as complex structure, high cost, and high maintenance expenses. This paper, based on the practical experience of the Hainan Lingshui Swimming Pool project, uses numerical calculations to analyze the mechanical characteristics of a ground-based movable roof’s track beam and roof structure. The results show that by using a two-point lifting method based on the center of gravity and structural characteristics, finite element simulations indicate that the top of the inverted L-shaped main beam deflects upward by 0.27 cm, and the cantilever end deflects downward by 2.08 cm. Under the combination of dead load + live load, the semi-ground-based roof has a mid-span deflection of 70 mm, with linear and nonlinear stability safety factors of 5.9 and 3.2, respectively. After optimizing the track beam, the deformation at 15 m did not meet the requirements, and the cost at 20 m was too high. Ultimately, a pile length of 18 m was selected. Full article

This study analyzes the deformation and internal force changes of the main tunnel during the cutting process of the pipe jacking method for cross passages. A combination of field monitoring and numerical simulation was used to investigate a construction case of the pipe jacking method for the cross passage of Zhengzhou Metro Line 12. The study provides an in-depth analysis of the stress characteristics of the main tunnel structure during the segment-cutting process. The research findings indicate that during the pre-support stage, the internal support system helps to disperse external water and soil pressure, thereby reducing the internal forces and deformation of the tunnel. In the segment-cutting stage, the horizontal diameter of the main tunnel near the hole location gradually increases, while the vertical diameter decreases. At the same time, the stress on the bolts also rises, with the circumferential bolt stress exceeding that of the longitudinal bolts, eventually approaching their yield strength. The upper and lower ends of the tunnel opening are cut to form cantilever ends, leading to inward converging deformation. This deformation causes the internal forces to disperse toward both sides of the opening, resulting in a noticeable increase in internal force at the 90° position of the semi-cutting ring. The research findings provide a theoretical reference for understanding the deformation patterns and internal force transfer mechanisms of the main tunnel structure during the construction process of cross passages using the pipe jacking method. Full article

During the cantilever casting construction process of continuous girder bridges, it is crucial to accurately predict the pre-camber of each cantilever segment to ensure smooth closure of the bridge, structural safety, and construction quality. However, traditional methods for predicting pre-camber have limited accuracy and primarily handle linear relationships. Therefore, this paper proposes a pre-camber prediction model based on a Convolutional-Bidirectional Long Short-Term Memory network with a fusion attention mechanism (CNN-BiLSTM-Attention) and utilizes the Dung Beetle Optimizer (DBO) algorithm to optimize the hyperparameters of the CNN-BiLSTM-Attention model to enhance its predictive performance. The research results indicate that compared to several other prediction models, the model proposed in this paper demonstrates superior performance in predicting the pre-camber of continuous girder bridges. Compared to other prediction models, the evaluation metrics MAE, RMSE, and MAPE of the model proposed in this paper are minimized to 2.76 mm, 3.47 mm, and 0.70%, respectively. Applying the model proposed in this paper to the cantilever casting stage of the elevated continuous girder bridges in Shenyang Metro, China, enables pre-camber prediction with an accuracy of an average absolute error of less than 2 mm, providing a new efficient method for pre-camber prediction in cantilever casting construction. Full article

Structural instability in marine scaffold systems often causes serious economic losses and casualties. In this study, a multi-parameter coupled model was established based on the MIDAS GEN finite element analysis platform to investigate the influence mechanisms of key parameters on the overall stability of marine scaffold systems. To quantify the impact levels of the key parameters, a sensitivity analysis framework was established using an orthogonal experimental design approach and the corresponding compliance detection index and instability early-warning mechanisms were proposed. The results indicate that the overall stability of the scaffold system initially increases and then decreases with the rise in the adjustable base height. Variations in the cantilever length of the adjustable bracket within the range of 100–650 mm have no significant effect on the system’s overall stability. The absence of diagonal brace at the bottom, top, and facade ends significantly reduces structural stability. Increased vertical offset markedly degrades stability, whereas horizontal offset within ±5 mm has a negligible effect. The key parameters affecting the structural stability, ranked in descending order of significance, are as follows: absence of diagonal braces, verticality offset of the vertical bar, height of the adjustable base, horizontality offset of the horizontal bar, and cantilever length of the adjustable bracket. Finally, an early-warning assessment system for the scaffold structure was established. The research findings provide valuable guidance for optimizing marine scaffold design, enhancing construction safety, and formulating relevant standards and specifications. Full article

During the construction of concrete-filled steel tubular (CFST) arch bridges, hollow steel tube arch ribs are typically erected using the cantilever method with cable hoisting. In this construction stage, the arch ribs exhibit low out-of-plane stiffness and are thus highly susceptible to wind-induced vibrations, which may lead to cable failure or even collapse of the structure. Despite these critical risks, research on the aerodynamic performance of CFST arch ribs with different cross-sectional forms during cantilever construction remains limited. Most existing studies focus on individual bridge cases rather than generalized aerodynamic behavior. To obtain generalized aerodynamic parameters and buffeting response characteristics applicable to cantilevered CFST arch ribs, this study investigates two common cross-sectional configurations: four-tube trussed and horizontal dumbbell trussed sections. Sectional model wind tunnel tests were conducted to determine the aerodynamic force coefficients and aerodynamic admittance functions (AAFs) of these arch ribs. Comparisons with commonly used empirical AAF formulations (e.g., the Sears function) indicate that these simplified models, or assumptions equating aerodynamic forces with quasi-steady values, are inaccurate for the studied cross-sections. Considering the influence of the curved arch axis on buffeting behavior, a buffeting analysis computational program was developed, incorporating the experimentally derived aerodynamic characteristics. The program was validated against classical theoretical results and practical measurements from an actual bridge project. Using this program, a parametric analysis was conducted to evaluate the effects of equivalent AAF formulations, coherence functions, first-order mode shapes, and the number of structural modes on the buffeting response. The results show that the buffeting response of cantilevered hollow steel arch ribs is predominantly governed by the first-order mode, which can be effectively approximated using a bending-type mode shape expression. Full article

This paper presents a physics-informed training framework for projection-based Reduced-Order Models (ROMs). We extend the original PROM-ANN architecture by complementing snapshot-based training with a FEM-based, discrete physics-informed residual loss, bridging the gap between traditional projection-based ROMs and physics-informed neural networks (PINNs). Unlike conventional PINNs that rely on analytical PDEs, our approach leverages FEM residuals to guide the learning of the ROM approximation manifold. Our key contributions include the following: (1) a parameter-agnostic, discrete residual loss applicable to nonlinear problems, (2) an architectural modification to PROM-ANN improving accuracy for fast-decaying singular values, and (3) an empirical study on the proposed physics-informed training process for ROMs. The method is demonstrated on a nonlinear hyperelasticity problem, simulating a rubber cantilever under multi-axial loads. The main accomplishment in regards to the proposed residual-based loss is its applicability on nonlinear problems by interfacing with FEM software while maintaining reasonable training times. The modified PROM-ANN outperforms POD by orders of magnitude in snapshot reconstruction accuracy, while the original formulation is not able to learn a proper mapping for this use case. Finally, the application of physics-informed training in ANN-PROM modestly narrows the gap between data reconstruction and ROM accuracy; however, it highlights the untapped potential of the proposed residual-driven optimization for future ROM development. This work underscores the critical role of FEM residuals in ROM construction and calls for further exploration on architectures beyond PROM-ANN. Full article

During long-span arch bridge construction, repeated adjustments of large cantilevered segments and nonuniform cable tensions can lead to deviations from the desired arch profile, reducing structural efficiency and increasing labor and material costs. To precisely control the process of cable-stayed buckle construction in long-span arch bridges and achieve an optimal arch formation state, a constrained optimization for the buckle and anchor cable forces under one-time tension is developed in this paper. First, by considering the coupling effect of the cable-stayed buckle system with the buckle tower and arch rib structure, the control equations between the node displacement and cable force after tensioning are derived based on the influence matrix method. Then, taking the cable force size, arch rib closure joint alignment, upstream and downstream side arch rib alignment deviation, tower deviation, and the arch formation alignment displacement after loosening the cable as the constraint conditions, the residual sum of squares between the arch rib alignment and the target alignment during the construction stage is regarded as the optimization objective function, to solve the cable force of the buckle and anchor cables that satisfy the requirements of the expected alignment. Applied to a 310 m asymmetric steel truss arch bridge, the calculation of arch formation alignment is consistent with the ideal arch alignment, with the largest vertical displacement difference below 5 mm; the maximum error between the measured and theoretical cable forces during construction is 4.81%, the maximum difference between the measured and theoretical arch rib alignments after tensioning is 3.4 cm, and the maximum axial deviation of the arch rib is 5 cm. The results showed the following: the proposed optimization method can effectively control fluctuations of arch rib alignment, tower deviation, and cable force during construction to maintain the optimal arch shape and calculate the buckle and anchor cable forces at the same time, avoiding iterative calculations and simplifying the analysis process. Full article

In the application of digital twin technology for the heading workface in coal mining, real-time state data will be transmitted to the remote control platform through a gateway device. This cross-system and cross-software data transmission method inevitably introduces transmission delays, resulting in a certain spatiotemporal discrepancy in the virtual model control for the remote control of the physical equipment. In this paper, by analyzing the operational process of the cantilever roadheader, a state evolution dynamics model construction method for the cantilever roadheader is proposed, which includes three stages, the discretization of the operating state based on the cutting path, event-driven graph construction of the cutting state evolution, and real-time data-driven dynamics evolution, so to continuously monitor, analyze, and adjust the operational dynamics of the cantilever roadheader based on real-time state data, thus improving the efficiency, performance, and adaptability. The construction of the model provides a theoretical basis and technical support for the construction and alignment of the digital twin multidimensional model of the cantilever roadheader. Full article

This paper presents a Bayesian-based finite element model updating method that integrates static displacement measurements and dynamic modal data to simultaneously identify structural mass and stiffness parameters. By leveraging Bayesian inference, a posterior probability density function (PDF) is constructed by integrating static displacement and modal parameters, thereby effectively decoupling the identification of structural mass and stiffness. The Delayed Rejection Adaptive Metropolis (DRAM) Markov Chain Monte Carlo (MCMC) sampling algorithm is utilized to derive the posterior distributions of the updated parameters. To mitigate the computational burden associated with repetitive finite element (FE) analyses during large-scale MCMC sampling, a Kriging surrogate model is employed to efficiently approximate the time-consuming FE simulations. Numerical examples involving a cantilever beam and an actual concrete three-span single-box girder bridge illustrate that the proposed method accurately identifies simultaneous variations in mass and stiffness at multiple structural locations, effectively addressing parameter coupling and misidentification issues encountered when using either static or dynamic data alone. Moreover, the Kriging surrogate significantly improves computational efficiency. Experimental validation on an aluminum alloy cantilever beam further corroborates the effectiveness and practical applicability of the proposed method. Full article

The Tujia ethnic group is one of the major ethnic groups in China, with a long history and abundant cultural heritage. As a distinctive architectural style, Tujia dwellings have evolved over thousands of years, developing a wealth of construction techniques and embodying the wisdom of local craftsmen. These construction techniques are a valuable asset of Tujia folk dwellings but still rely on the oral tradition among craftsmen. Therefore, it is extremely valuable for enriching the world’s architectural system and heritage inheritance to refine these techniques and transform them into regularized digital properties. The “L”-shaped system of Tujia houses is the most common type of Tujia house, featuring both the main house and the wing house, and can distinctly represent the construction technology and style characteristics of Tujia houses. The grammar of “L”-shaped houses is the core part of the grammar of Tujia houses and is also important for analyzing and inheriting the construction technology of Tujia houses. Shape grammar is an analytical method centered on the refinement of rules. This paper takes advantage of its ability to analyze and refine rules, and based on the rich Tujia architectural material library, it summarizes the corpus and refines the grammatical rules of “Generation of the main structure framework”, “Roof truss conversion and support”, “Side houses and stilted structures”, and “Cantilevered elements and corners” into four dimensions, along with many detailed grammars. These rules are transformed into a programming language and parameterized toolkit, providing a detailed summary of the construction logic and techniques. Ultimately, an “L”-shaped construction grammar for Tujia traditional dwellings has been proposed, and with the help of software tools such as Grasshopper, the digital regeneration has been completed. Full article

This study assesses the wind resistance and vortex-induced vibration (VIV) risks of the Dongzhou River Bridge in China reconstruction during critical construction stages. Computational Fluid Dynamics (CFD) simulations analyzed wind effects when the twin main girders were maximally separated, revealing asymmetric vortex shedding patterns influenced by upstream–downstream aerodynamic interactions. The upstream girder’s wake generated complex flow fields, increasing turbulence on the downstream girder and indicating elevated VIV susceptibility. A 1:50 scale aeroelastic model validated these findings through wind tunnel tests, confirming that CFD-predicted critical VIV wind speeds aligned with experimental observations. Tests identified a distinct “jump-like” vibration mode at specific wind speeds (35–40 m/s full-scale equivalent), characterized by abrupt amplitude escalation rather than gradual growth—a signature of unstable VIV resonance. However, measured amplitudes remained below the 61.5 mm full-scale equivalent safety threshold, confirming that vibrations posed no critical risk. While aerodynamic coupling between girders requires monitoring during cantilever construction, the study concludes that existing control measures ensure safe construction and operation without structural modifications. These results provide actionable guidelines for wind risk mitigation through construction sequencing and real-time wind speed restrictions. Full article