European Journal of Computational Mechanics

Research on Seismic Mechanical Characteristics of Multi-Story Frame Structures in Prefabricated Buildings

Li Jianwei, Zhao Yongquan, Niu Haoshuang — Thu, 26 Feb 2026 00:00:00 +0100

As an important structural form of prefabricated buildings, multi-story frame structures are mainly composed of vertically load-bearing frame columns and horizontally connected beams, featuring good structural stability and strong seismic resistance. Compared with the traditional cast-in-place reinforced concrete frame structure, the core feature of the prefabricated frame lies in that its structural components are prefabricated in the factory and then transported to the site to be assembled into an integral structure through specific connection techniques. This revolutionary change in construction methods, while bringing about improvements in efficiency and quality, has also profoundly altered the force transmission mechanism and failure mode of structures. The key to its seismic performance is largely determined by the performance of the connection nodes between prefabricated components, especially the beam-column nodes. This paper focuses on the seismic mechanical characteristics of multi-story frame structures in prefabricated buildings. Through numerical simulation, the mechanical response features of multi-story frame structures under seismic loads are systematically analyzed. Two different strength grades of concrete show similar trends in bearing capacity and deformation capacity. When the axial compression ratio increases, the bearing capacity and yield displacement of the structure are smaller. When the yield strength of longitudinal reinforcing bars increases, the structure has a higher bearing capacity, initial stiffness and greater yield displacement. It has a stronger adaptability when plastic deformation occurs. Structures with a lower reinforcement ratio have a lower bearing capacity and, as the load increases, the rate at which the bearing capacity decreases is faster.

A Plasticity-Based Constitutive Framework for Multi-Scale Modeling of Mechanical Degradation in PEM Fuel Cell Membranes

Jaka Dujc — Thu, 26 Feb 2026 00:00:00 +0100

The long-term durability of polymer electrolyte membranes (PEMs) remains one of the key barriers to the widespread deployment of fuel cells. This work presents a plasticity-based constitutive framework for predicting membrane degradation under cyclic hydration and thermal loading. The model combines hydration- and temperature-dependent elasticity, swelling, and plastic strains with a pinhole growth law that is activated only when both mechanical plasticity and chemical degradation are present. A binary fluoride release rate (FRR) switch is introduced to couple chemical activity with defect growth in a computationally efficient manner.

Simulation results reproduce key experimental and modeling trends from the literature. Larger hydration amplitudes $Δ λ$ accelerate void growth and plastic strain accumulation, while thermal swings increase hydrostatic stresses and material softening, thereby enhancing defect evolution. The framework thus provides a physically consistent rationale for the coupled influence of hydration variability, thermal cycling, and chemical degradation on membrane lifetime.

While simplified in geometry and chemistry, the present approach captures the irreversible nature of plastic deformation and remains tractable for long-term cycling studies. It provides a robust basis for future extensions toward 2D/3D analyses and for integration into multi-physics durability assessments of PEM fuel cells.

Lattice Element Model Elastic Behaviour in Solid Mechanics: Bayesian-Based Calibration and Fine-Tuning

Duje Pavić, Noemi Friedman, Hermann G Matthies, Mijo Nikolić — Thu, 26 Feb 2026 00:00:00 +0100

This work investigates the elastic behaviour of a mechanical discrete lattice element model based on Timoshenko beam elements. Due to the selected irregular meshes generated with Delaunay triangulation and one-dimensional elements, lattice models struggle to correctly simulate a wide range of elastic material responses, particularly in capturing lateral deformations associated with variations in the material’s Poisson ratio. To address this limitation, we introduce correction coefficients that modify the stiffness properties of the lattice beam elements, influencing the global mechanical behaviour of the lattice. A Bayesian stochastic identification framework is chosen to calibrate these coefficients using a set of standard mechanical tests, ensuring consistency with the proper continuum elastic response. The applicability of the identified lattice element stiffnesses is evaluated across different loading conditions and material properties. The methodology ensures a fine tuning of the model, accuracy in simulating mechanical deformations, and the basis for non-linear phenomena, crack initiation and its propagation across the lattice.

A Parametric Study of Elastic Web Buckling in Steel Plate Girders with Transverse Stiffeners

Emina Hajdo, Emina Hadzalic, Adnan Ibrahimbegovic — Thu, 26 Feb 2026 00:00:00 +0100

This study presents a numerical investigation into the elastic buckling behaviour of steel plate girders with transverse stiffeners, focusing on the web buckling mode. The influence of key parameters, including web thickness, stiffener thickness and spacing, and flange-stiffener connectivity, is examined to understand their effect on the critical buckling load associated with this mode. Elastic buckling analyses are carried out for various combinations of these parameters using a finite element model based on a nonlinear shell element formulation, which incorporates von Kármán-type nonlinear strain-displacement relations to effectively capture geometric nonlinearities and local instability phenomena. The results are systematically presented and discussed to highlight the sensitivity of buckling performance to each parameter. Detailed insights are provided into the underlying structural behaviour, revealing trends and interactions that govern the elastic web stability of steel plate girders with transverse stiffeners across different design configurations.

Integrated Flood Hazard Assessment using GIS and 2D Hydraulic Modelling: A Case Study of Sanica River, Bosnia and Herzegovina

Nerma Lazović, Ajla Mulaomerović-Šeta — Thu, 26 Feb 2026 00:00:00 +0100

Flood extent maps (FEM) and flood hazard maps (FHM) serve as legal instruments for spatial planning, decision-making, strategic flood risk planning, and public awareness, supporting sustainable and safe land use along the river corridor. This study aims to improve existing FEM and create FHM for the Sanica river, prone to frequent flooding. The existing FEM were developed using a 1D HEC-RAS model under steady-flow conditions, applying a single uniform Manning roughness coefficient along the entire river reach. The study presents the first application of an unsteady 2D HEC-RAS model along Sanica river, integrating LiDAR-based topography and updated hydrological data to derive FEM and FEH for common return periods. The final 2D hydraulic model was selected through calibration of seven variants of the Manning roughness coefficient, three lumped and four distributed, with the optimal configuration identified based on three goodness-of-fit measures. The comparison of 1D and 2D FEM shows close agreement in morphologically confined canyon reaches, while significant differences occur in river sections with floodplain inundation and dominant 2D flow. These results indicate that model dimensionality can be selected based on reach-scale morphology, enabling the use of 1D models in canyon sections to reduce computational time, while applying 2D models only where complex flow dynamics are present within the Sanica river study area.

Optimization of the Performance of Bimorph Piezoelectric Energy Harvesters with Honeycomb Metamaterials Using Artificial Neural Networks and NSGA-II

Mohamed Taha Mhiri, Walid Larbi, Mnaouar Chouchane, Mohamed Guerich — Thu, 26 Feb 2026 00:00:00 +0100

Honeycomb-based metamaterials have recently attracted considerable interest for their potential in energy-harvesting applications. In this paper, we focus on two types of bimorph harvesters incorporating honeycomb substrates with positive and negative Poisson’s ratios (PPR and NPR). The substrates are coupled with piezoceramic (PZT) layers to enable electromechanical conversion. To improve energy-harvesting efficiency, we propose an optimization framework that integrates finite element (FE) simulations for data generation, a pretrained neural network for rapid performance prediction and the NSGA-II evolutionary algorithm for multiobjective optimization. The proposed strategy enables the identification of optimal geometric parameters of the honeycomb cells, particularly for cantilever resonators where the fundamental vibration modes are critical and must be tuned to specific eigenfrequencies for engineering applications. The optimization is applied to an initially unoptimized bimorph harvester with a honeycomb substrate. The simulation results indicate that an optimized harvester with an NPR metamaterial substrate can increase the power-to-mass ratio at a resonance frequency of 160 Hz by approximately 14.72% compared to the unoptimized honeycomb harvester. Moreover, compared to a harvester with a solid substrate, the improvement reaches 5%. Furthermore, a life cycle analysis was conducted, showing that the honeycomb substrate can significantly increase the operational lifetime of the piezoceramic layer. This improvement arises because the honeycomb substrate reduces the equivalent stress on the active layer. At high acceleration levels, the predicted operational lifetime is enhanced by more than tenfold compared to the solid substrate, since the PZT material is brittle and lacks flexibility. This improvement is notable because it surpasses the typical lifespan of both standard button batteries and rechargeable batteries highlighting a strong potential of this design for future applications.

Method of Variable Material Properties for Small Elastoplastic Deformations

Nives Brajčić Kurbaša, Blaž Gotovac, Vedrana Kozulić — Thu, 26 Feb 2026 00:00:00 +0100

This work presents a mesh-free formulation that combines the method of variable material properties (MVMP) with a collocation method based on finite atomic basis functions (ABF) for the analysis of small elastoplastic deformations. Unlike existing approaches that update only the tangent modulus of material hardening, the presented method simultaneously updates the elastic modulus $E$ and Poisson’s ratio $ν$ (i.e., Lamé constants $λ$ and $μ$ ) as smooth fields. This reduces the nonlinear problem to a sequence of linear elasticity problems. The algorithm is implemented using a strong formulation and the finite Fup₄ basis functions from the class of algebraic ABFs. Fup₄ is an infinitely differentiable function that exactly reproduces polynomials up to the fourth degree, maintains the continuity of higher derivatives, and thus ensures numerical stability and fast convergence of the collocation-based MVMP procedure. Due to the compact support of the basis functions and the choice of the positions of the collocation points, the matrix of the equations system retains its band form throughout all iterations, which improves the conditioning of the system and accelerates convergence. The accuracy of the proposed approach has been verified on two classical benchmark problems with analytical solutions: a one-dimensional bar under axial load and a thin cylindrical disc subjected to internal pressure.

Editorial

Adnan Ibrahimbegovic, Mijo Nikolić — Thu, 26 Feb 2026 00:00:00 +0100

This special issue contains six selected papers first presented in short for- mat at the 7th International Conference ECCOMAS MSF 2025 Multi-scale Computational Methods for Solids and Fluids, organized in Dalmatian capital Split, Croatia, 25–27 June 2025.