Foam concrete is a lightweight material characterized by low density and moderate mechanical strength, which can be combined with aluminum alloys to form a novel type of column. Such composite members enable rapid assembly, disassembly, and functional reconfiguration in prefabricated structures. However, research on the axial compressive performance of this new column system remains limited. This study investigates the axial behavior of aluminum alloy-foam concrete short columns through a combination of numerical simulation, theoretical analysis, and machine learning prediction enhanced by the SHAP (SHapley Additive exPlanations) interpretability method. A three-dimensional finite element model was developed in ABAQUS to examine the effects of frame thickness, foam concrete strength, and section dimension on load-bearing capacity. The results indicate that the column sectional dimensions have a significant influence on the axial compressive capacity. The foam concrete strength and frame thickness have relatively smaller effects. In addition, the frame thickness can effectively restrain lateral deformation and delay buckling. Based on the confinement mechanism, polynomial fitting, Mander’s model, and a composite column formulation were proposed for axial capacity prediction. Furthermore, eleven machine learning models were trained on 64 simulation datasets 64 independent computational experiments, among which the Gradient Boosting Decision Tree (GBDT) demonstrated the best performance (R² = 0.9984, MAE = 5.97, RMSE = 7.51). SHAP analysis further revealed the relative contributions of key features, showing that section dimension is the most influential parameter, followed by foam concrete strength, while frame thickness contributes the least. These findings not only enhance the theoretical understanding of the load-transfer mechanism of columns but also provide reliable predictive models and analytical formulations for their application in lightweight prefabricated structures.

A lightweight and high-strength structural system is increasingly demanded in prefabricated and sustainable construction; however, accurately evaluating the mechanical behavior of novel composite members remains challenging. This study proposes an aluminum alloy foam concrete composite column consisting of an embedded aluminum alloy frame and foam concrete infill. Material tests, a full-scale axial compression test, and finite element-based parametric analyses were conducted to verify the hypothesis that composite action between the embedded aluminum alloy frame and foam concrete governs the axial load-transfer mechanism and bearing capacity of the proposed column. The results show that initial cracking mainly occurred in the middle region of the column along the diagonal brace direction, while the composite column maintained favorable elastic performance under relatively high load levels. The aluminum alloy frame provided a semi-passive confinement effect on the foam concrete, although this effect gradually weakened with increasing load due to lateral deformation of the diagonal braces. Moreover, an appropriate arrangement of interlocking keys significantly improved the composite action and overall stability of the column. These findings provide experimental and numerical evidence for assessing the axial compression performance of aluminum alloy foam concrete composite columns and offer guidance for the design and optimization of this novel lightweight structural system.

To investigate the dynamic compressive behavior and deformation characteristics of medium-carbon Cr-Ni-Mo high-strength steel under different strain rates and temperatures, quasi-static tensile and compression tests, together with Split Hopkinson Pressure Bar (SHPB) dynamic compression tests, were conducted. The Johnson–Cook flow stress and damage model parameters were calibrated based on the experimental results under the investigated loading conditions. Combined with macroscopic morphologies of recovered specimens, SEM fracture observations, and finite element simulations, the deformation and damage behavior of the material was investigated. The results show that the material exhibits pronounced strain-rate strengthening and thermal softening characteristics. At 298 K, increasing the strain rate from 1000 to 5000 s⁻¹ increases the mean maximum compressive stress from 2263.1 to 2500.9 MPa, while expanding the plastic deformation range. At 1000 s⁻¹, increasing the temperature from 298 to 698 K decreases the mean maximum compressive stress from 2263.1 to 1722.2 MPa. The calibrated Johnson–Cook model reasonably describes the stress response and deformation characteristics at different strain rates at 298 K, with relative errors of simulated maximum compressive stresses below 4% for the representative experimental curves used in the numerical comparison. The macroscopic and microscopic observations reveal that increasing strain rate promotes the localized shear deformation, inclined cracking, and partial fragmentation after plastic compression, with enhanced shear deformation features reflected by elongated dimples, fracture steps, and tear ridges. Increasing temperature reduces fragmentation under high strain-rate loading and promotes the formation of coarse dimples and plastic flow features. Numerical analysis further indicates that increasing strain rate promotes the localization of equivalent plastic strain, leading to inclined shear bands and crack formation.

This study addresses the challenges of slow attenuation and significant hazards associated with explosive shock waves confined within conventional underground tunnel walls. A novel serrated passive shock-attenuating tunnel design is proposed, grounded in the principle of viscous dissipation within the boundary layer. The investigation encompasses both experimental analyses and numerical simulations. The study found that shock waves in smooth tunnels primarily propagate as one-dimensional plane waves, resulting in concentrated energy and gradual attenuation. Conversely, the serrated tunnel geometry generated a continuous reflection, scattered and vortex formation due to abrupt geometric discontinuities, led to distortion and fragmentation of the shock front and the emergence of a three-dimensional discrete pressure field. Through turbulent dissipation mechanisms, energy is rapidly transformed into small-scale vortices, effectively reducing wave velocity and markedly diminishing the forward peak pressure. Under conditions of high-equivalent explosions, the serrated structure demonstrates enhanced efficacy in energy dissipation and peak pressure attenuation, significantly curtailed the effective propagation distance of high-pressure shock waves. Optimization of the serration spacing identified 30 cm as the optimal interval, minimizing stress peaks both centrally and at the tunnel entrance, thereby maximizing wave attenuation. Comparative analysis between simulation and experimental was resulted that corroborates the wave-attenuation performance of the serrated design, offering a critical foundation for the development of blast-resistant underground structures.