In rock engineering, understanding the strength and failure mechanisms of heterogeneous crystalline rocks is important for rock mass stability and engineering safety. The macroscopic mechanical properties of these rocks are influenced by microstructural characteristics at the grain scale. However, the effects of heterogeneity on failure mechanisms remain unclear. This study uses the discrete element method with the Voronoi algorithm to construct a three-dimensional grain-based model, and investigates the effects of mineral grain orientation, morphology (aspect ratio), and number on the anisotropic mechanical behavior of gneiss. Results show that grain orientation (β) dominates strength anisotropy: uniaxial compressive strength follows a U-shaped distribution, while Young’s modulus increases monotonically with β. When the aspect ratio exceeds 2:2:0.3, the influence of schistosity on strength decreases, weakening the U-shaped trend and shifting the failure mode from conjugate shear to tensile fracture. Increasing particle number enhances modulus anisotropy but has limited effect on strength anisotropy. By incorporating deformable particles and differentiated contact properties, this study establishes a mapping between micro-geometric parameters and macroscopic mechanical responses, providing a refined framework for rock mass stability evaluation.
The present study evaluates the feasibility of using recycled construction and demolition waste (CDW) as a partial and full replacement for natural sand in mortar, with emphasis on mechanical performance and thermal stability. Mortar mixes containing 0
To the best of the authors’ knowledge, no previous study has employed a higher-order shell theory to investigate rotating sandwich cylindrical shells with a magnetorheological elastomer (MRE) core. Moreover, the coupled effects of fluid–structure interaction and hygrothermal environment have not yet been incorporated into such spinning MRE-based shell systems. Motivated by this research gap, the present work investigates the free vibration behavior of rotating functionally graded graphene origami metamaterial (FG-GOM) sandwich cylindrical shells with an MRE core conveying fluid and subjected to thermal and moisture conditions within the framework of a higher-order shear deformation shell theory. Different GOM dispersion patterns governed by a piecewise rule are investigated. The formulation of the motion equations based on the suggested higher-order theory represents a significant analytical challenge, which is further intensified by incorporating the MRE core into the structural model. The interaction force between the viscous fluid and the sandwich shell is modeled using the Navier–Stokes equations, where the fluid velocity is taken into account in describing the fluid–structure interaction. The motion equations with simply-supported conditions are solved analytically using Navier method. To demonstrate the validity of the proposed formulation, the obtained results are compared with those reported in the literature. In addition, an extensive parametric investigation is conducted to evaluate the influence of several key parameters on the vibration characteristics of the sandwich cylindrical shell having a MRE core with spinning motion.
Recent advancements in seismic retrofit strategies have focused on low-impact, rapid, and reversible interventions, with self-centering rocking dual-frame (SCR-DF) systems demonstrating strong potential for enhancing the seismic resilience of reinforced concrete (RC) buildings. These systems, typically integrated as exoskeletons, improve seismic resistance by combining dissipative devices with post-tensioning and column uplift mechanisms to provide self-centering capability, thereby limiting residual deformations and facilitating rapid post-earthquake recovery. This research examines the development and effectiveness of a SCR-DF system applied as an external dissipative exoskeleton to enhance the seismic resilience of a real case study RC building. The expected seismic behavior of the SCR-DF system is validated through simulation results. Equations predicting the load-deformation behavior of the rocking systems are developed, ensuring accurate control of key limit states for reliable performance. Design parameters—such as frame configurations, overturning moment resistance, fuse properties, and post-tensioning stress—are optimized based on the inelastic behavior of the existing structure using a displacement-based design procedure. Nonlinear computational analyses are used to validate these designs. The peak interstory drift ratios (IDR) of the retrofitted building are significantly reduced compared to those of the existing structure, reaching approximately 0.69
