Search Results (1,433)

Blasts, vehicle collisions, and other unexpected incidents may cause lateral impacts on building structures, which threaten their safety. This paper investigates the impact resistance of cold-formed steel (CFS) L-shaped built-up columns (LBC). Firstly, a finite element model (FEM) was established and validated through experiments conducted by the authors. Then, a parametric analysis was conducted to quantify the effects of axial compression ratio, impact velocity, and dimensions on the impact response. The results indicated that: (1) The peak lateral impact force of the specimens presented a significant nonlinear trend with increasing axial compression ratio, and an optimal axial compression ratio was found as about 0.3. (2) Higher impact velocity intensified both force and displacement responses of the specimens, and both lateral impact peak force and maximum displacement increased significantly with the impact velocity. When the impact velocity rose from 3.13 m/s to 6.26 m/s, the peak force and maximum displacement increased by an average of 38.2% and 96.5%, respectively. (3) Increasing the cross-sectional dimensions and steel thickness, and reducing screw spacing, could significantly enhance the impact resistance and deformation capacity of the specimens. This study reveals the failure mechanism of such members and the laws of parameter influence, which can be used for impact design of CFS-LBC. Full article

Integral abutment bridges (IABs) are increasingly adopted in transportation infrastructure due to their durability, reduced maintenance needs, and cost-effectiveness compared to conventional bridges. However, their reliable performance under live loads is strongly influenced by the nonlinear soil–structure interaction (SSI) at the pile–abutment joint, which remains challenging to quantify using conventional analysis methods. This study develops simplified spring-based models to capture the SSI behavior of pile–abutment joints in short-span IABs. Predictive equations for joint rotation, deflection, moment, and shear are formulated using Linear Regression (LR) and Response Surface Methodology (RSM). Unlike prior studies relying solely on FEM or traditional p–y curves, the novelty of this work lies in deriving regression-based spring constants calibrated against FEM analyses, which can be directly implemented in standard structural software. This approach significantly reduces computational demands while maintaining predictive accuracy, enabling efficient assessment of pile contributions and global bridge response. Validation against finite element method (FEM) results confirms the reliability of the simplified models, with RSM outperforming LR in representing nonlinear parameter interactions. Full article

Predicting early-age temperature evolution in mass concrete is crucial for controlling thermal cracks. This process involves two distinct physical stages: an initial, hydration-driven heating stage (Stage I) and a subsequent, environment-dominated cooling stage (Stage II). To address this challenge, we propose a novel two-stage hybrid modeling strategy that decouples the underlying physical processes. This approach was developed and validated using a 450-h on-site monitoring dataset. For the deterministic heating phase (Stage I), we employed polynomial regression. For the subsequent stochastic cooling phase (Stage II), a Random Forest algorithm was used to model the complex environmental interactions. The proposed hybrid model was benchmarked against several alternatives, including a physics-based finite element model (FEM) and a single Random Forest model. During the critical cooling stage, our approach demonstrated superior performance, achieving a Root Mean Square Error (RMSE) of $0.24°\mathrm{C}$. This represents a 17.2% improvement over the best-performing single model. Furthermore, cumulative error analysis indicated that the hybrid model maintained a stable and unbiased prediction trend throughout the monitoring period. This addresses a key weakness in single-stage models, where underlying phase-specific errors can accumulate and lead to long-term drift. The proposed framework offers an accurate, robust, and transferable paradigm for modeling other complex engineering processes that exhibit distinct multi-stage characteristics. Full article

Thin liquid film corrosion is a critical failure mechanism for the atmospheric environment and industrial infrastructure. This review systematically examines relevant methods and recent advances in characterizing and simulating this phenomenon. Various measurement methods for liquid film thickness, composition, and conductivity are investigated, with particular focus on the advantages of non-contact optical technology and X-ray fluorescence (XRF) in in situ monitoring and analysis. For corrosion simulation, the finite element method (FEM), cellular automaton (CA), and molecular dynamics (MD) are widely used. Their combination has synergistic potential in revealing essential corrosion mechanisms and establishing prediction models across scales. Full article

This study presents a flutter answer analysis of the Romanian IAR-99 HAWK advanced trainer aircraft equipped with multiple external store configurations. A high-fidelity finite element model (FEM) of the complete aircraft, including pylons and external stores, was coupled with a Doublet Lattice Method (DLM) aerodynamic model. The aeroelastic framework was validated against Ground Vibration Test (GVT) data to ensure structural accuracy. Four representative configurations were assessed: (A) RS-250 drop tanks on inboard pylons and PRN 16 × 57 unguided rocket launchers on outboard pylons; (B) four B-250 bombs; (C) eight B-100 bombs mounted on twin racks; and (D) a hybrid layout with B-100 bombs inboard and PRN 32 × 42 launchers outboard. Results show that spanwise distribution governs aeroelastic stability more strongly than total carried mass. Distributed stores lower wing-bending frequencies and densify the modal spectrum, producing critical pairs and subsonic crossings near M ≈ 0.82 at sea level, whereas compact heavy loads remain subsonic-stable. A launcher-specific modal family around ≈29.8 Hz is also identified in the hybrid layout. The validated FEM–DLM framework captures store-driven mode families (≈4–7 Hz) and provides actionable guidance for payload placement, certification, and modernization of the IAR-99 and similar platforms. Full article

This study investigates the influence of frame material on the thermal behavior of motors and mechanical performance in First Person View (FPV) drones operating under extreme payloads. Two identical 7-inch quadcopters were constructed, differing only in the lower frame section material: carbon fiber-reinforced polymer (CF) or aluminum alloy 6061-T6 (AL). Both drones were subjected to 5-min hover tests with and without a 20 N payload, and their performance was assessed through infrared thermography, vibration analysis, flight log data, and finite element method (FEM) thermal simulations. Under no-load conditions, both frames showed comparable motor temperatures (37–44 °C). With payload CFframe motors exceeded 90 °C, indicating severe overheating, while ALframe motors remained below 60 °C, approximately 30 °C cooler, and demonstrated a more uniform temperature distribution between motors. Power analysis revealed higher consumption for the AL frame drone at no load due to its greater mass, but lower consumption under payload, likely because motor efficiency was maintained. Vibration analysis indicated fewer and lower-frequency resonances for the AL frame. FEM simulations, using boundary conditions from flight data, reproduced the experimental temperature distributions, confirming their reliability for predictive design. The overall results show that aluminum frames, although denser, enhance thermal regulation and dynamic stability in demanding UAV operations, providing practical guidance for defense, search-and-rescue, and other critical applications. Full article

A disc-shaped double-layer shell structure reinforced by stiffeners is introduced for underwater gliders. Based on the finite element method integrated with automatic matching layer (FEM/AML) technology and the direct boundary element method (DBEM), the acoustic response of a disc-shaped double-layer shell with six longitudinal ribs within the frequency range of 10–500 Hz is obtained. The resonant frequencies of the sound pressure level (SPL) correlate with the structural–acoustic modes. At resonance frequencies, the acoustic directivity and spatial sound pressure distribution of the double-layer shell exhibit symmetry relative to the mid-cross-section. The influence of longitudinal rib counts on vibro-acoustic behavior is investigated. The analysis results of frequency–spatial spectrum for radiated sound pressure reveal that the resonant frequencies migrate to the mid-high frequency with increases in the longitudinal rib quantity. Full article

This study analyzed the dynamic behavior of EN C45 structural steel under impulse loading generated by a pressure wave. The experiments were conducted on a special test rig using two load configurations: (I) direct contact of the load with the sample surface and (II) detonation at a distance of 30 mm. Depending on the loading conditions, the specimens were fragmented or developed extensive internal cracks and plastic deformations. To complement the experimental program, hybrid numerical simulations were performed using the finite element method (FEM), smoothed particles hydrodynamics (SPH), and coupled Euler–Lagrange (CEL) approach. A modified Johnson–Cook (JC) model was used to account for dynamic damage and cracks. Computed tomography (CT) and metallographic analyses provided detailed information on the formation of cracks in MnS inclusions, brittle cracks near the sample axis, and shear deformation zones away from the axis. These observations allowed direct correlation with the predicted numerical deformation and damage fields. The innovative nature of this work lies in the combination of three complementary computational techniques with computed tomography analysis and microstructure analysis, providing a comprehensive framework for describing and confirming the mechanisms of damage and fragmentation of structural steels under explosive loading. Full article

This article presents a unique study on the demolition process of a high-rise reinforced concrete building simulated using a methodology based on the Applied Element Method (AEM). Prior to the parametric analyses, the progressive collapse-based solid model was visually validated against real-world controlled demolition footage captured by both Unmanned Aerial Vehicles (UAVs) and fixed cameras, showing close agreement in building motion and debris dispersion patterns. In contrast to the Finite Element Method (FEM) model, the simulation is not blast-induced; it is instead developed on a column removal approach, which is widely adopted in progressive collapse assessments. Discussions related to the FEM model are provided as well. The parametric analysis is conducted in two stages. First, a constant removal sequence (removal of 4, 3, and 2 floors, respectively, in the first, second, and third axes) is applied to both 20- and 15-storey buildings under three time delays: 100 ms, 300 ms, and 500 ms. Based on these results, a 300 ms delay is identified as a suitable compromise for controlling debris dispersion, and this value is adopted for the subsequent analyses. In the second stage, three distinct removal sequences are examined on the 20-storey structure using the fixed 300 ms delay: Scenario 1 (4–3–2), Scenario 2 (12–8–6), and Scenario 3 (16–12–6). Among these, Scenario 3 yields the most compact horizontal debris spread. The findings indicate a strong correlation between the actual demolition behavior and the proposed model, demonstrating its capability to realistically capture complex structural failure mechanisms and provide practical guidance for optimizing controlled demolition strategies. Full article

Symmetry plays a key role in the study of stress and strain analysis of spherical tanks, as described in detail in the main text. The inherent geometric symmetry of a spherical tank–being uniform in all directions from its center–allows for significant simplification of finite element models. This radial symmetry means that the stress and strain fields under uniform internal pressure are also symmetrical, reducing the computational domain to a small, representative portion of the tank rather than the entire structure. By using these symmetry principles, the study not only ensures the accuracy of its predictions but also achieves a high degree of computational efficiency, making complex engineering problems easier and more accessible. The application of symmetry, therefore, is not just a theoretical concept but a practical tool that underlies the methodology and success of this analysis. This study investigates the mechanical behavior of a spherical tank subjected to internal fluid pressure, utilizing the finite element method (FEM) as a primary analytical tool. Spherical tanks are widely used for the storage of various fluids, including liquefied natural gas (LNG), compressed gases, and water. Their design is critical to ensure structural integrity and safety. This research aims to provide a comprehensive stress and strain analysis of a typical spherical tank, focusing on the hoop and meridian stresses, and their distribution across the tank’s geometry. A 3D finite element model of a spherical tank will be developed using commercial FEA software. The model will incorporate realistic material properties (e.g., steel alloy) and boundary conditions that simulate the support structure and internal fluid pressure. The analysis will consider both linear elastic and potentially non-linear material responses to explore the tank’s behavior under various operational and overpressure scenarios. The primary objectives of this study are as follows: (1) determine the maximum principal stresses and strains within the tank wall, (2) analyze the stress concentration at critical points, such as support connections and nozzle penetrations, and (3) validate the FEM results against classical analytical solutions for thin-walled spherical pressure vessels. The findings will provide valuable insights into the structural performance of these tanks, highlighting potential areas of concern and offering a robust numerical approach for design optimization and safety assessment. This research demonstrates the power and utility of FEM in engineering design, offering a more detailed and accurate analysis than traditional analytical methods. Full article

Different combinations of round and flat tensile specimens for different gripping systems of Austempered Ductile Irons (ADIs) were produced from the same 25 mm Y-block castings to investigate the effect of the specimen geometry and gripping system on the tensile mechanical properties of ADIs. Particular attention was paid to the analysis of strain-hardening behavior of ADIs that can be related to the stability of ausferrite, when austenite transforms into martensite. Moreover, Digital Image Correlation (DIC) was carried out on the flat tensile specimens to analyze the strain distribution of the material in real time. To quantify the austenite stability with plastic deformation, X-ray Diffraction (XRD) analysis was performed on ADIs before and after straining. Finally, Finite Element Modeling (FEM) simulations were carried out to analyze the stress distribution along the tensile specimens in all the different tensile testing configurations (tensile specimen geometry + gripping system). The flat specimens showed lower ductility and higher strain-hardening rates; however, the flat tensile specimens with the wedge gripping system experienced the highest strain-hardening rate, suggesting a significant decrease in the ausferrite stability in this tensile testing configuration. FEM simulations showed that the specimen geometry and the gripping system influenced the tensile behavior of ADI by reducing the ductility because of stress intensification and triaxiality effects. Furthermore, the stress intensification and triaxiality factor caused a higher strain-hardening rate, which was associated with increased ausferrite instability. Full article

This article presents a methodology for estimating the gripping forces in a Fin Ray-type gripper, based on the integration of experimental and computational approaches. The development and validation methods includes (1) mechanical modeling and material selection; (2) experimental tests to relate FG finger displacement to maximum applied force using a load cell; (3) validation of the computational model through finite element method (FEM) simulations in ABAQUS using experimental data; and (4) experimental analysis of the FG handling a chicken egg, with the FEM determining the stress applied to the egg. The computational results showed a maximum stress of approximately 7 MPa on the egg, with no signs of damage, demonstrating the FG’s suitability for handling delicate objects in both the experimental and computational procedures, thus enabling safe object handling without causing damage. This work advances research on Fin Ray-type flexible end-effectors, emphasizing their utility in manipulating fragile objects without requiring complex force and pressure control algorithms. Full article

This study proposes an optimal design approach incorporating rotor skew to reduce torque ripple in a 5 kW in-wheel axial flux permanent magnet (AFPM) motor. Nine design variables, including the skew angle, were selected for optimization. The variation ranges of these variables were defined, and sample points were generated using the optimal Latin hypercube design (OLHD). Response data corresponding to the sample points were obtained through three-dimensional finite element method (3D FEM) analysis. Metamodels were then constructed using five different methods and evaluated based on the root mean square error (RMSE). The optimization results showed that the average torque of the optimized model increased by 2.3% compared with the initial design, reaching 48.85 Nm. Torque ripple was reduced by 42.01% to 2.83 Nm, while peak-to-peak cogging torque decreased by 42.76% to 2.61 Nm. In addition, efficiency improved by 0.07% to 95.53%, and the total harmonic distortion (THD) of the back-EMF waveform was reduced by 50.72% to 2.4%. These findings demonstrate that the proposed method provides an effective and systematic design strategy for enhancing the performance of AFPM motors. Full article

The article concerns the internal insulation of a utility room located in the attic of a building from the late 1990s. Due to the freezing of the external wall, an analysis of heat flow through this wall was conducted. Various insulation materials recommended for internal application were tested: EPS and resol board (100 mm thick) and an aerogel mat (10 mm thick). The analyses included the temperature distribution in the wall and indoor thermal conditions. Experimental studies determined the thermal conductivity coefficient (λ) of the selected insulation materials and the heat transfer coefficient for the analyzed wall. Numerical analyses were conducted with the TRISCO 12.0w software, which applies the finite element method (FEM), whereas the assessment of interlayer condensation risk was performed using the WUFI^® Pro 5.1 program. Full article

This brief editorial introduces the Special Issue “Computational Methods in Structural Engineering”. This Special Issue brings together recent advances in computational approaches—including finite element modeling, machine learning applications, stochastic analysis, and high-precision numerical methods— highlighting their increasing influence on the analysis, design, and assessment of modern structural systems. The published contributions cover topics such as the nonlinear finite element method (FEM) for structural response under extreme loading, advanced plate and composite modeling, explainable AI for material characterization, machine learning for predictive performance modeling, data-driven signal processing for structural health monitoring, and stochastic analysis of dynamic inputs. Through this collection of studies, this Special Issue underscores both the opportunities and the challenges of applying advanced computational methods to enhance the resilience, efficiency, and understanding of structural engineering systems. Full article