Investigation of train aerodynamic characteristics and dynamic responses induced by wind load mutation in pylon area of double-deck truss girder bridge

ABSTRACT For complex steel structures, the substitution of physical trial assembly with virtual assembly has the potential to significantly reduce both manufacturing costs and time. However, current pre-assembly verification methods face challenges in accurately quantifying assembly deviations that arise from the accumulation of manufacturing tolerances. To address this issue, the present study proposes an innovative framework that integrates Design for Manufacturing and Assembly (DFMA) principles to facilitate efficient data exchange. By synthesising Building Information Modelling (BIM) engines with DFMA theory, a Pre-Assembly Analysis System (PAS) and a data-driven conflict detection algorithm have been developed to elucidate the cumulative impact of manufacturing deviations on assembly accuracy. Validation through the use of a large-span cantilever steel truss structure demonstrated that the PAS effectively performs essential functions, such as geometric inspection and assembly conflict identification, thereby significantly enhancing assembly precision. This research offers an efficient digital solution for lean construction in steel structures.

PhysScaleFormer: A multiscale physics-enhanced deep learning framework for real-time dynamic response prediction in vibratory truss structures

Dynamic layout optimization of truss subjected to a time-dependent load by isogeometric-analysis-based stiffness spreading method

Engineering optimization problems are increasingly complex, requiring more sophisticated approaches to locate global optima. This paper presents the Adaptive Hybrid Optimization (AHO) algorithm, which addresses the limitations of single-equation update mechanisms and conventional linear decay schedules through three structural contributions. First, the algorithm implements four distinct position-update strategies, selected uniformly at random at each agent update, ensuring continuous structural diversity throughout the optimization process. Second, a dual-leader probabilistic guidance mechanism directs each search agent using asymmetric weighting between the top two solutions. Third, a nonlinear power-changing control parameter D replaces the conventional linear decay schedule used in existing algorithms such as WOA and GWO, providing 43% more total exploration budget while maintaining faster late-phase exploitation. AHO is validated on 23 benchmark functions from the CEC2005 suite and on seven constrained engineering problems, including four space truss structures: the 10-bar Truss Design, the 25-bar Spatial Truss, the 72-bar Spatial Truss, and the 120-bar Dome Truss. Friedman ranking analysis across all 23 benchmark functions ranked AHO first among the eight algorithms tested, with an overall best rank of 1.78 and an overall mean rank of 1.84. Wilcoxon signed-rank test results confirm statistically significant improvement over five of seven competitor algorithms on more than 19 of 23 benchmark functions, with AHO achieving the best overall Friedman rank of 1.78 across all 23 functions. On the four truss optimization problems, AHO achieves the best ranking across all five performance metrics against all seven competitor algorithms under an equal budget of 50,000 structural function evaluations per run. Performance analysis demonstrates competitive convergence behaviour and solution quality compared with the selected benchmark methods.

To investigate the differences in biomechanical performance between the Bailey bridge screw fixation system derived from truss units and the conventional volar locking plate-screw fixation system in the treatment of type C distal radius fractures, and to explore a simpler and minimally invasive internal fixation configuration. Based on the radial CT data of a healthy female volunteer, a finite element model of type C distal radius fracture was established, and the plate-screw group (PS group) and the Bailey bridge screw group (FMB group) were assembled respectively, with 2.7mm screws adopted in both groups. Material parameters, boundary conditions and four physiological loading conditions (axial, rotational, palmar flexion, dorsiflexion) were set uniformly. The mesh size of 1mm was determined through mesh convergence analysis, and the deformation scale factor of 1.0 and the color scale range of 0 ~ 0.66mm were unified. The displacement amplitudes of the two groups of models were compared at the levels of the overall structure, internal fixation devices and articular surface. The maximum displacement amplitudes of the PS group under axial, palmar flexion and dorsiflexion conditions were 0.1636, 0.3760 and 0.0915mm, respectively, with a reduction of 32.7, 37.7 and 84.9% compared with the FMB group, showing better rigidity. The FMB group exhibited advantages only under the rotational condition, with a maximum displacement amplitude of 0.2308mm, a 65.0% reduction compared with the PS group. In terms of displacement distribution, the PS group showed a characteristic of local concentration, with high-displacement areas located at the contact area between the plate and the fracture end, the distal screw holes of the plate, and the dorsal and ulnar margins of the articular surface; the FMB group presented uniform displacement distribution at the fracture end, each screw and the entire articular surface without obvious concentrated areas. At the level of internal fixation devices, the displacement of the plate in the PS group was concentrated at the distal screw holes, while the displacement of the truss screws in the FMB group was evenly distributed. Moreover, the FMB group achieved fixation performance comparable to that of the PS group with less material. The conventional plate-screw fixation system has higher overall rigidity under multi-directional loads, and is suitable for patients with type C distal radius fractures who require rigid fixation and early weight-bearing. The Bailey bridge screw fixation system realizes load distribution by virtue of the truss structure, which has the advantage of minimal invasiveness and excellent stability under rotational condition, making it suitable for patients pursuing minimally invasive treatment and requiring early rotational functional exercise. This study provides a new option for the individualized internal fixation treatment of type C distal radius fractures, and also offers a new idea for the interdisciplinary integrated design of engineering structural science and orthopedics.

Balancing the strength and toughness of materials remains a long-standing core challenge in materials science. In this study, a novel design strategy for Al2O3/Mg interpenetrating phase composites (IPCs) is proposed. Al2O3 ceramic scaffolds with two types of Split-P triply periodic minimal surface (TPMS) structures (shell-type and solid-type) were fabricated via stereolithography (SLA) and then infiltrated with AZ91D magnesium alloy using lost foam casting (LFC), and consequently, Al2O3/Mg IPCs were successfully fabricated. In the proposed method, cocontinuous interpenetration of ceramic and metal phases is achieved, ultimately forming a dense interlocking structure with no interfacial delamination and a relative density exceeding 95%. Quasi-static compression tests and finite element simulations confirm that the as-built composites exhibit a compressive strength of up to 187.5 MPa and a specific energy absorption of 11.18 J/g; among them, the solid-type IPC shows a slightly higher compressive strength, while the shell-type IPC demonstrates superior energy absorption performance. The excellent performance of the IPCs is attributed to the TPMS structure that effectively mitigates the local stress concentration prone to occur in traditional truss structures, along with the synergistic strengthening effect between ceramic and metal phases that substantially improves the plastic deformation capacity and energy dissipation efficiency of the composites. This study provides a new idea for the design and fabrication of high-strength and lightweight composites, which hold significant application potential in lightweight load-bearing and impact-resistant energy-absorbing fields.

Aerodynamic stabilizers have been widely applied to enhance the flutter performance of long-span bridges. This study investigates the flutter behavior of the girder of a mountainous long-span truss-suspension bridge. It also analyzes the effects of stabilizer plates with different geometric parameters on the optimization of girder flutter performance under large angles of attack (AoA). Wind tunnel tests indicate that, at high AoA, the flutter performance of the truss girder increases with the height of the upper central stabilizer. For horizontal stabilizers, there exists an optimal width at which the girder achieves the best flutter performance. Flutter derivatives under various conditions were obtained through forced vibration tests, and the mechanism by which stabilizer parameters enhance girder flutter performance was analyzed using the work done by self-excited moments. As the height of the central stabilizer increases, the wind speed corresponding to the transition of the self-excited forces from negative to positive continuously rises. In contrast, as the width of the horizontal stabilizer increases, the corresponding wind speed first increases and then decreases, indicating the existence of an optimal width that maximizes flutter performance. Finally, computational fluid dynamics (CFD) simulations were conducted to examine the flow field around the truss girder. The results show that increasing the central stabilizer height leads to a more uniform vortex distribution above the bridge deck, while increasing the horizontal stabilizer width causes premature flow separation. At the optimal width, flow separation prevents vortices beneath the deck from attaching behind the chord members, thereby enhancing aerodynamic stability.

ABSTRACT In systems engineering, solution spaces provide a practical way to reconcile competing goals by working with sets of good designs instead of point‐based solutions. Earlier contributions, however, were restricted either by limiting the dimensionality per component or, more recently, by constraining these spaces to be convex, which can, in some cases, significantly restrict the available design freedom–usually, box‐shaped solution spaces include only a fraction of the complete solution space even in simple cases, and convex component solution spaces can still present considerable losses for problems with non‐convex complete solution spaces. In this paper, we introduce a new method to, for the first time, compute non‐convex component solution spaces for arbitrary performance functions and any number of design variables per component. By iteratively removing bad space only as so‐called corner boxes, loss of solution space is significantly reduced while maintaining crucial independence between components. Demonstrations with diverse truss structures with varying geometries and material properties, with constraints on tip deflection, show admissible regions up to eleven orders of magnitude larger than box‐shaped solutions and three orders of magnitude larger than convex component solution spaces, thus unlocking substantially more design freedom without sacrificing robustness. This can be useful in structural design for material selection before specifying geometric component details. The numerical characteristics and trade‐offs of using this new method are studied with up to 21 components and up to seven design variables per component.

This study proposes a graph edge-attention network (GEAN) to include the topological features and physical information of structures using a graphic representation in the model training process. Unlike conventional graph attention network-based models, which compute message-passing weights solely from node features, GEAN introduces an edge-attention mechanism to jointly model structural node and edge features. The message-passing weights are determined based on stiffness information of structures, enabling the model to capture the influence of element stiffness on force transmission and enhancing physical interpretability. Three numerical examples with different dimensions are used to evaluate the performance of the proposed method. The results demonstrate that GEAN achieves significantly competitive prediction results compared to traditional surrogate and graph neural network-based models. As the dimensionality of the problems increases, GEAN with affordable samples consistently keeps the prediction error around 3%, far smaller than that of the other surrogate-based approaches.

Introduction. Bamboo structures have become widespread in Asia, Africa, and Latin America. Bamboo is a gradient material with unequal cross-sectional properties and characteristic anisotropy: good properties in the longitudinal and weak transverse directions. The connection of bamboo rods thereby represents a weak point in the design, which is a scientific issue. In modern literature, the lack of the efficiency of various types of bamboo rod joints has been shown leading to a progressive collapse of a structure. The identified gaps in the existing research has enabled us to formulate the aim of the article, which is to develop new types of bamboo rod connections to ensure safe and reliable operation of the truss structure. Materials and Methods. The object of the study is a bamboo truss with a wall thickness of at least 10 mm. The trusses were calculated by means of the advanced methods of cutting nodes, selecting cross-sections, and designing influence lines. Research Results. A new design for connecting bamboo rods in the spatial case has been set forth. The advanced spatial hinge is a one-piece hot-forged steel sphere with 18 threaded holes and a machined support surface at angles of 45°, 60° and 90° in relation to each other. A conical steel section is attached at each end of the spatial structure element to transfer force from the bamboo joints to the nodal ones. Due to this tapering cone-shaped section, the nodal joints can be connected to lots of elements at once. The pedestrian bridge truss has been calculated for various load application options. It is shown that the suggested type of connection ensures efficient operation of the spatial structure. The actual reliability factor of 2.33 is 29% over the traditional value. Discussion and Conclusions. The suggested options for ensuring a reliable connection of bamboo rods are of primary importance in the design and construction of bamboo truss structures of a spatial type. A spherical hinge and a conical attachment with a metal cable create a reliable connection, which is critical for bridge-type structures or residential buildings. The prospects of the work are focused on investigating the efficiency of the suggested compounds in dynamic tasks under a moving load and creep.

Additive manufacturing of lattice structures offers superior lightweight and energy-absorbing properties across aviation, automotive, and biomedical sectors. However, achieving dimensional precision remains a primary obstacle to ensuring design compatibility and product functionality. To address this challenge, this study introduces a novel comparative analysis of BCC, Diamond, and Octet Truss geometries, specifically focusing on the interplay between infill density and strut thickness. By evaluating PLA-fabricated plates with thicknesses of 0.8 mm, 1 mm, and 1.2 mm through microscopic CAD-to-print comparison, the research identifies critical accuracy thresholds. Findings demonstrate that higher infill ratios significantly enhance structural stability; notably, Octet Truss structures exhibited substantially lower dimensional deviations (0.694%–1.923%) compared to BCC structures (1.25%–3.546%). Furthermore, increasing strut thickness to 1.2 mm reduced deviation rates by up to 50% compared to 0.8 mm struts. These results provide a significant resource for optimizing additive manufacturing parameters, offering new insights into achieving high-precision fabrication for complex lattice systems.

Traditional design of space grid structures typically relies on the assumption of pinned joints. While this simplification streamlines the evaluation of member importance, it fails to account for the semi-rigid behavior of actual connections. This discrepancy often leads to inaccuracies in structural analysis and member importance ranking, introducing potential risks of misjudgment. To overcome these limitations, this study develops a more refined evaluation framework. First, a high-fidelity finite element model (FEM) of a semi-rigid space grid was established, incorporating joint rotational stiffness. Members were simulated using segmented beam elements, and the model's accuracy was rigorously validated against experimental data. Subsequently, a comprehensive evaluation index was proposed based on structural strain energy, which integrates multiple internal force components, including axial force, bending moment, and shear force. Finally, the proposed method was applied to a regular square pyramid space grid to compare member importance rankings against traditional methods. The underlying internal force redistribution mechanisms were analyzed by selecting representative members with significant ranking discrepancies. The results indicate that while both methods show consistent trends for most members, substantial differences exist in critical regions, such as the top chords. Mechanism analysis reveals that the traditional pinned-joint model, by neglecting moment transfer, results in simplified load paths and stress concentrations, thereby overestimating the importance of specific members. In contrast, the semi-rigid model accurately reflects the diversified load-transfer mechanisms facilitated by joint moments. This study confirms that joint semi-rigidity significantly influences the assessment of member importance. The proposed method effectively identifies and corrects misjudgments caused by the pinned-joint assumption, providing a more reliable theoretical basis for identifying critical components and optimizing maintenance strategies, particularly for complex space structures requiring high assessment precision.

Flexural behavior of UHPC-enhanced concrete filled steel tubular composite truss girders

Real-time modal parameter identification of a variable-topology truss structure via transporting robots

Abstract The paper focuses on developing a simple symmetric planar truss structure that could be effectively used to understand and study nonlinearities in large structures. A simple two-member truss model was defined and used for the study. A simple analytical model was derived using the theories of first and second order, which were then solved using the numerical formulations. To validate the model, an experimental setup was created and mounted on a tensile testing machine to apply required loads on the system. The results obtained from the test are used to validate the numerical model. Different parametric studies were conducted using the validated model to further understand the effects of the different variables on the model’s behaviour.

ABSTRACT Group theory has profoundly advanced physics and chemistry in systems with symmetries. Yet its use in structural engineering applications has not yet been fully explored beyond the aesthetics of symmetric designs. This work addresses two significant gaps that have limited the broader adoption of group‐theoretic methods in structural vibration analysis and clarifies their implications for structural design when multiple eigenvalues arise. First, a problem‐independent approach is presented with detailed derivations for constructing group representations for symmetric structures directly from the ‐invariance for structural vibration analysis. This method applies effectively to both dihedral groups and the higher‐order Platonic groups, including tetrahedral (), octahedral (), and icosahedral () symmetries. The method used in this work scales well with structural complexity and enables both explicit and canonical block diagonalizations. Second, this work provides a comprehensive guide to applying finite‐point‐group representations in structural vibration analysis and proves that the dimensions of irreducible representations determine eigenfrequency multiplicities. Although no optimization is performed in this work, this theoretical result has direct implications for structural optimization, resolving longstanding misconceptions about the coalescence of eigenvalues by showing that symmetry is the origin of repeated eigenfrequencies. The theoretical developments are validated on truss structures with dihedral and higher‐order symmetries, accurately predicting their eigenfrequency distributions.

To address the issues of premature convergence and insufficient local search capability in genetic algorithms (GAs), this article proposes a hybrid optimization algorithm: the harmony search–genetic algorithm (HS-GA). By integrating the principles of GA and harmony search (HS), this algorithm significantly enhances global and local search capabilities through fine division of the GA population and adaptive optimization of crossover and mutation probabilities for each subgroup. It is suitable for truss structure optimization design with both discrete and continuous variables. Size optimization analyses based on classical truss examples demonstrate that, under structural constraints, HS-GA reduces structural weight by an average of 9.27% and 4.69% compared to GA and the improved genetic algorithm (IGA) (across three examples), respectively, exhibiting superior comprehensive performance.

Tubular members in truss structures allow for spanning large distances with reduced self-weight. To facilitate manufacturing, transportation, and assembly, these members are subdivided and therefore require connections to join the segments. One example is the sleeve connection, which uses through bolts and eliminates the need for welded or flanged joints, making assembly quicker and more practical. The present study aimed to conduct a theoretical and numerical analysis of the influence of the edge-to-hole distance in sleeve connections with aligned bolts, applied to thin-walled square hollow sections. For this purpose, a numerical analysis was carried out using the finite element method through ANSYS software, with variations in edge-to-hole distance of 2, 2.5, 2.7, 3, and 3.5 times the bolt diameter, as well as variations in the number of bolts between 2 and 3. From this study, the possible failure modes of the connection were identified, with the dominant failure mode being the bearing failure of the bolt holes, also observed in the theoretical evaluation, occurring in the outer tubes. Furthermore, variations in the edge-to-hole distance and the number of bolts did not change this failure mode.

The dynamic analysis of structures differs from static analysis mainly due to the consideration of load variations over time. Harmonic loads, also known as cyclic loads, are among the most critical factors requiring precise evaluation to predict structural behavior accurately. These loads involve periodic variations over time, such as those induced by earthquakes, wind, or traffic, and can lead to complex responses in structures, including significant nonlinear effects. Thus, it is essential to design buildings to ensure safety and comfort, avoiding unexpected performances. In dynamic analysis, the use of computational simulations is crucial, as it provides more precise results and enables complex analyses to which a building may be subjected. This approach allows for the anticipation of potential problems and ensures that both static actions (self-weight, permanent loads) and dynamic actions (winds, vibrations, impacts) are properly considered and verified. Then, the main objective of this work was to develop a methodology for the dynamic analysis of 2D reinforced concrete truss structures, considering the physical nonlinearity of the material (cracking). To achieve this objective, Finite Element Method (FEM) was employed for the spatial discretization of the structure domain, and Newmark method was used for the temporal discretization. Physical nonlinearity was considered through the material's constitutive equation, according to ABNT NBR 6118:2023, with the update of the stiffness matrix over time. Newton-Raphson method was used to obtain the solution of the nonlinear problem in the process of verifying the reinforced concrete section. The results obtained were compared with those of well-established market software in their student, free, or temporary versions to validate the robustness and efficiency of the proposed algorithm.