The nanocomposite structures reinforced with carbon nanotubes (CNTs) and graphene platelets (GPLs) in the functionally graded distributions have been intensively studied as an advanced composite structure. However, these studies were conducted for each nanocomposite without comparison, assuming that the structure was not damaged without cracks. In this context, the present study intends to compare the mechanical behaviors between the CNT- and GPL-reinforced composite plates with and without crack in the linear and nonlinear ranges. The numerical method is developed in the framework of 2-D extended natural element method (XNEM) in which the crack line is represented by the phase-field formulation (PFF) and the crack-induced singularity is captured by the crack-tip singular functions. The developed numerical method is validated through the benchmark test, and the mechanical responses of the CNT- and GPL-reinforced composite plates are compared with respect to the total volume fraction and the distribution pattern of nanofillers, the crack angle and CNT alignment, and the boundary condition. The numerical results reveal that the developed numerical method accurately predicts the linear and nonlinear mechanical responses of cracked nanocomposite plates. And, the comparative numerical results found that the GPL-reinforced composite plate is much stiffer than the CNT-reinforced one which exhibits the remarkable dependence on the CNT alignment.

Externally Bonded (EB) and Near-Surface Mounted (NSM) are the two well-known systems for strengthening Reinforced Concrete (RC) beams in flexure using Fiber-Reinforced Polymer (FRP) materials in the shapes of sheets, plates, bars, etc. Previous experimental research proved the effectiveness of the NSM FRP system compared to the EB FRP system. In this field, the current research presents a comparison between these systems using Cast3m software and theory. The beams were modeled in a 2D model, and the FRP materials were perfectly embedded in the concrete surface in order to ensure failure by FRP rupture. Firstly, the ability of the numerical model in predicting the flexural behavior of strengthened RC beams was tested against earlier experimental results. In this context, a good agreement between the predicted and the experimental results was obtained, where a significant convergence between P-Δ curves and similarity in failure way were observed. After that, the comparison was carried out. Hence, the comparison confirmed the effectiveness of the NSM FRP system in terms of strength, ductility, and economy. Moreover, it comes out that the use of NSM FRP system decreased the tension area and the stresses in concrete.

In this work, a time-domain nonlinear finite element model, considering an effective semi-explicit/explicit time integration procedure, is proposed to analyse ground-borne vibrations. In this approach, stabilized calculations and reduced governing systems of equations are enabled, eliminating the typical restrains of explicit time-marching algorithms, and providing a reduced computational effort solution procedure. In this sense, the present methodology combines the best features of both explicit and implicit standard formulations. In addition, iterative computations are not necessary in the discussed semi-explicit/explicit strategy, further greatly improving the efficiency of the proposed procedure when nonlinear models are regarded. To demonstrate the effectiveness of the discussed formulation, first, the classical Lamb's problem is studied and the obtained results, regarding accuracy and efficiency, are compared to those provided by the Newmark and Bathe methods, illustrating the much better performance of the proposed approach. In the sequence, ground-borne vibrations arising from pile driving are analysed, following a parametric study. In this case, a nonlinear hyperbolic model is employed to describe the soil behavior, and an axisymmetric finite element formulation is considered to describe the coupled soil-structure model. Comparisons with standard numerical approaches and previously reported results, available in the literature, are also provided for this problem, once again illustrating the excellent performance of the proposed formulation to effectively analyse complex wave propagation models.

This work examines the influences of rotational field and fractional heat time derivatives on thermal, acoustic, and optical wave propagation in nano-scale hydrodynamic semiconductors. Utilizing photo-thermoelasticity theory, we model the coupled wave behavior, incorporating the impact of rotation and fractional heat effects, which introduce nonlocality and thermal anisotropy. Normal mode analysis is applied to derive the boundary conditions at the hydro-semiconductor surface, which are addressed with continuity conditions for temperature under the laser excitation with recombination process, stress, and displacement, alongside thermal flux conditions. Numerical solutions highlight the influence of rotation, nonlocality, and fractional heat time derivatives on wave propagation. Graphical representations of the main fields demonstrate wave interaction dynamics, showing the dependence on rotational frequency and fractional order. The results reveal significant alterations in wave behavior due to the combined rotational and fractional thermal effects, offering insights into advanced material design and novel applications in nano-semiconductor devices.

Evolutionary algorithm-based size optimization of plane and space truss structures is studied for sequential loading scenarios. Size optimization of a truss is a search for the most suitable cross-sectional areas of the truss members from the available design spaces. The novelty of the present work lies in developing an evolution-based algorithm that can consider the sequential loading scenario while designing the planner and space trusses. Fortran-based computer programming has been developed for the proposed optimization method considered here. A standard displacement-based finite element method is implemented to obtain the trusses' nodal displacement and elemental stresses. To assess the performance of the proposed algorithm three plane trusses (3-bar, 18-bar, and 200-bar) and three space trusses (22-bar, 25-bar, and 72-bar) with various displacement and stress constraints under sequential loading have been considered. The optimum weights obtained from all the problems considered here have been analyzed and compared with the same, as obtained from other methods mentioned in the existing literature. It is important to note here that the results are in close agreement and in some cases optimum weights obtained from the present study are even better than the earlier results. Finally, a real-life design problem of an industrial roof truss has been considered to assess the applicability of the proposed algorithm. The convergence study and optimum cross-section of the truss have been reported as a case study.

Based on experimental study on the cross-joints of concrete-filled PVC-CFRP (Polyvinyl Chloride-Carbon Fiber Reinforced Plastics) tubular column-RC (Reinforced Concrete) beam connected with core steel tubes, this study selects appropriate constitutive relations of materials and failure criteria, and establishes a finite element model using ABAQUS software to investigate the seismic mechanical behavior of such joints under low-cycle reversed loading. The hysteretic curve and skeleton curve derived from finite element simulation are in good agreement with the experimental results, proving the validity of the finite element model. Based on this, the study analyzes the stress distribution of the concrete in the joint area and the inner and outer concrete of the core steel tube in the loading process, and explores the ultimate failure mode of such joints. Finally, the experimental parameters are extended to study the effects of concrete strength grade, core steel tube radius-thickness ratio, joint area stirrup ratio, and axial compression ratio on the skeleton curve and stiffness degradation of the joint. The stress mechanism of the joint under low-cycle reversed loading is analyzed, and relevant design and structure requirements are proposed to provide a reference for the experimental design and engineering application of this type of joint.

This paper aims to demonstrate a predictive model for the flexural behavior of isotropic, orthotropic, and laminated plates resting on Winkler-Pasternak elastic foundation type. This study utilizes An Innovative integral hyperbolic higher-order shear deformation theory that requires only four unknowns. The model incorporates shear deformation effects while satisfying zero shear stresses at the plate's free edges, eliminating the need for shear correction factors. The developed theories are based on a novel displacement field description that includes terms involving indefinite integrals to minimize the number of unknowns. The governing equation, derived from the virtual displacement is solved using Navier's analytical solution. The results obtained in the current study are consistent with available results in the existing literature. Additionally, the proposed theory is intriguing and shows promise for investigating further problems related to the mechanical behavior of plates due to their reduced variable count.

This paper studies seismic performance of a tall full-frame building with a thick-slab transfer substructure on depot. The thick- slab transfer substructure is comprised of the reinforced concrete shear wall, the reinforced concrete frame and the concrete thick transfer slab. A prototype with a scaling ratio of 1:15 is designed and fabricated to feasibly test and to reasonably assess structural dynamic characteristics under different earthquake intensities. The earthquake intensities are simulated by wave vibration of 0.118 g, 0.337 g, 0.741 g, and 1.347 g on a shaking table. A finite element analysis (FEA) model is developed and verified with the experimental results. The test results show that the superstructure is yielded before the substructure failure, whereas the reinforced concrete frame structure is intact under the excitation of peak ground acceleration of 1.347 g. The verified FEA model is used to investigate three structural layout angles of 60°, 45° and 0°. The structural seismic behaviors of the different layout angles between the reinforced concrete shear wall and the reinforced concrete frame are discussed. The FEA results show that the dynamic responses are significantly affected by layout angles of the single tower.