Aug 2026· Journal of fire sciences· 0 citations· 23 references
Abstract
This study presents the development of a three-dimensional finite element model for simulating the fire behavior of prestressed glued-laminated timber. The finite element model, based on experimental data and the recommendations of Eurocode 5, accounts for the temperature-dependent evolution of the wood’s physical and mechanical properties. It enables a realistic prediction of the residual load-bearing capacity and post-fire structural behavior of timber beams following fire exposure and cooling to ambient temperature and has been validated through simulations of full-scale fire tests reported in the literature. Despite advances in numerical modeling, the fire behavior of such structures has been subject to only limited numerical investigations, with most studies being experimental or analytical. In this context, the proposed model provides a robust numerical tool capable of accurately analyzing fire performance and identifying char formation zones. The calculated temperature profile at the fire-exposed surface closely matches experimental results, and the temperature trends at different beam depths show only minor deviations from measurements. Furthermore, the maximum deviation between the predicted and measured char layer thickness after 60 min of fire exposure is approximately 4.4%, demonstrating the model’s accuracy in reproducing thermomechanical transfers within wood under higher temperatures. These results confirm that the model can reliably predict both the temperature distribution and char formation in prestressed glued-laminated timber beams during fire exposure.
This study investigates the thermomechanical behavior and rehabilitation of RC beams strengthened with fiber-reinforced polymers (FRP) under high-temperature conditions, which are critical during fire exposure. A detailed finite-element model (FEM) was developed to simulate the structural performance of RC beams strengthened with three types of FRP laminates: carbon (CFRP), glass (GFRP), and aramid (AFRP). The model captures material nonlinearity, bond behavior, and temperature-dependent properties to analyze the effects of elevated temperatures (up to 800°C) on beam deflection, stress distribution, bending moment, and shear force. The study focuses on identifying the critical temperature at which each FRP type begins to lose effectiveness, providing insights into their thermal resistance. Additionally, the response surface methodology (RSM) was employed to predict and optimize the structural performance under various thermal and loading conditions. The RSM model demonstrated high predictive accuracy (
R
2
>
0.99
), validating the reliability of the numerical approach. Results showed that CFRP exhibits superior structural performance and thermal stability compared with GFRP and AFRP, particularly at temperatures up to 500°C. The findings emphasize the effectiveness of CFRP as a reliable rehabilitation solution for fire-damaged RC structures.
Objective
. This work is devoted to a quantitative assessment of the effect of internal prestressing of reinforcement on the stress-strain state and load-bearing capacity of a thick-walled cylindrical shell.
Method
. The study is carried out through a computational experiment using the finite element method in an axisymmetric formulation. The physical nonlinearity of concrete is described by the Sargin diagram, the parameters of which are verified according to Eurocode 2 data.
Result
. An iterative algorithm based on the method of variable elasticity has been developed for correcting the secant modulus of concrete deformations. The reinforcement is modeled discretely, and the prestressing effect is specified as initial stresses in the reinforcement elements. The modeling results showed that for a cylinder made of B40 concrete with a reinforcement percentage of 3.11%, failure under internal pressure is of a deformation nature and is associated with reaching ultimate tensile strains in the concrete, rather than with the exhaustion of compressive strength. The ultimate internal pressure for a non-stressed structure is 0.55 MPa. A hoop prestressing threshold of 265 MPa has been determined. Exceeding this threshold causes unacceptable tensile stresses in concrete even before the initial operational phase. It has been shown that the optimal hoop prestressing level of 250 MPa allows for doubling the ultimate internal pressure to 1.1 MPa.
Conclusion
. The developed numerical model and calculation algorithm enable predicting the behavior of reinforced concrete structures, taking into account the actual properties of materials and process factors. The obtained results demonstrate the high effectiveness of prestressing for thick-walled cylinders and highlight the need to control not only the strength but also the deformation criteria of concrete failure.
V. V. Kuznetsov, S. V. Litvinov, T. Volosatova· Herald of Dagestan State Tec...· 0 citations
This study presents a hybrid numerical modelling framework for predicting geometry, thermal history, and residual stresses in SS308L stainless-steel multiwall specimen manufactured by Wire Arc Additive Manufacturing (WAAM) on a low-alloy steel substrate. The model integrates macro-scale finite element thermomechanical simulation with analytical formulations for bead geometry, incorporating key physical phenomena such as Goldak double-ellipsoid heat source, and thermal expansion. Experimental deposition process was investigated under thermal camera. Simulated temperature histories at selected points demonstrated strong agreement with experimental thermal measurements, accurately capturing multiple thermal cycles associated with neighbouring bead depositions. Likewise, the numerical predictions of substrate distortion showed an average relative error below 5%, outperforming conventional macro-scale WAAM models. The simulated bead morphology locations closely matched the fabricated specimen, confirming the model’s capability to reproduce the overall bead morphology and macroscopic geometric deviations. The predicted residual stress distributions exhibited compressive and tensile regions qualitatively consistent with trends reported in previous WAAM studies. Since no direct residual-stress measurements were performed, these predictions should be interpreted qualitatively. Overall, the proposed study provides an efficient modelling framework for predicting thermal history, and distortion, while offering qualitative insight into macroscopic geometry and residual-stress evolution in WAAM components.
Alexandra Morvayovà, M. Karamimoghadam, N. Contuzzi et al.· Discover Surfaces· 0 citations
Numerical approaches based on the Discrete Element Method (DEM) have proven effective in reproducing complex cracking and failure mechanisms of masonry structures. However, when intending to use them for virtual testing, an important constraint is that their predictive capability strongly depends on the appropriate calibration of material and contact parameters. This study presents the calibration of three-dimensional DEM models developed in 3DEC to simulate in-plane response of full-scale masonry wall with opening, subjected to quasi-static monotonic lateral loading. The experimental results, including the lateral force–displacement relationship, crack patterns and damage mechanisms, are used as benchmark data for the numerical model with exact geometry, boundary condition and loading scenario. Two models were calibrated, composed of rigid blocks and elastic deformable blocks. In both cases the blocks were connected through contact interfaces governed by Mohr–Coulomb joint model. To capture results of the experimental test, a tailored joint-displacement-based softening model is introduced on subcontact scale, representing main novelty of the study. Calibration using the proposed joint model successfully captures the main features of experimental behavior, including initial elastic part, stiffness degradation, peak lateral load, and post-peak softening (including an abrupt decrease in lateral load bearing of the wall at proper displacement), together with experimentally found damage mechanisms. The results demonstrate the capability of DEM-based simulations to reproduce nonlinear in-plane behavior of masonry wall without need for fracture energy parameters and highlight the importance of accurate joint softening models for reliable structural assessment of masonry structures.
Habibollah Katouli, Katalin Bagi· Meccanica (Milano. Print)· 0 citations
IN718 superalloy components fabricated by selective laser melting (SLM) generally require subsequent machining and numerical simulation. However, Johnson-Cook (J-C) constitutive parameters specifically applicable to three-dimensional milling of SLM-IN718 and independently validated using milling forces and chip characteristics remain scarce, thereby limiting the predictive accuracy of finite element simulations of the cutting process. In this study, dynamic stress–strain curves over wide ranges of strain rate and temperature were obtained through split Hopkinson pressure bar (SHPB) tests. A second-order regression model correlating the J-C parameters with the resultant milling force was then established based on orthogonal finite element simulation data. Taking the relative error between the experimentally measured and finite element-predicted resultant milling forces in the steady cutting stage as the objective function, a genetic algorithm was employed to inversely identify the J-C constitutive parameters within physically reasonable ranges. In addition, the predictive capability of the model for material flow and chip formation was further evaluated by comparing the experimental and simulated chip morphologies and chip thicknesses at low, medium, and high cutting speeds. Consequently, a set of equivalent J-C parameters with satisfactory predictive performance under the investigated processing conditions and finite element modeling assumptions was obtained. Validation under 16 independent milling conditions showed that the optimized J-C parameters achieved an
R
2
of 0.973, an RMSE of 9.39 N, an AARE of 3.1%, and a maximum relative error of 6.63%. The model also reproduced the overall chip morphology and thickness variation reasonably well. These results demonstrate that the proposed method provides satisfactory mechanical prediction accuracy and physical consistency within the investigated processing and parameter ranges.
Hao Wang, Haiqing Bai, Pei Han et al.· Proceedings of the Instituti...· 0 citations
This study aims to numerically investigate the mode I, II, and III fracture behaviors of additively manufactured degradable, bioplastic polylactic acid (PLA) lattice specimens. Numerical simulations were performed using the eXtended Finite Element Method (XFEM) based on the extracted PLA's mechanical and fracture material properties. The maximum principal stress and fracture energy power‐law criteria were utilized to simulate damage initiation and evolution in three‐dimensional (3D) numerical analyses. To consider the effects of build orientation, the transversely isotropic elasticity model (TIEM) was implemented. To facilitate the XFEM analyses, the equivalent solid material model (ESMM) technique was also utilized. The experimental load‐displacement responses of single‐edge notched bending specimens under the symmetric and asymmetric four‐point bending and mode III transverse shear cracked plate tests were conducted for comparison with the XFEM analyses in mode I, II, and III fracture, respectively. A common calibration factor, as well as the simultaneous utilization of the TIEM model, as well as the XFEM and ESMM techniques, reflected numerical results of acceptable accuracy compared to the experimental results; 5.3% (3.4%), 4.4% (5.8%), and 9.6% (5.4%) differences for the stiffness (peak load) of mode I, II, and III specimens, respectively.
Bahman Paygozar, R. Gorguluarslan· Fatigue & Fracture of En...· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
