Abstract This article presents a comparative study of the reliability of reinforced concrete (RC) cross-sections subjected to simple bending, designed at the ultimate limit state and following the recommendations of the 2014 and 2023 versions of the Brazilian code NBR 6118. The analyses are based on reliability theory by implementing the FORM algorithm on three rectangular cross-section configurations, considering three constant values of dimensionless bending moments and five different concrete strength classes between C30 and C90. Although the elements designed by NBR 6118:2023 have shown additions of up to 19% in the total steel cross-section area as a consequence of the implementation of the strength reduction factor ( η c), the results show no significant improvements in reliability compared to the 2014 previous version of NBR 6118.

Abstract This article investigates the buckling and free vibration behavior of bio-inspired helicoid laminated composite (BiHLC) plates resting on a Pasternak foundation (PF) using the meshfree moving Kriging (MK) method for the first time. In this study, the MK method leverages Reddy's first-order shear deformation theory (FSDT) for analysis of the mechanical behavior of plates. The PF is characterized by two stiffness parameters: spring stiffness k 1 and shear stiffness k 2. A key advantage of the MK interpolation is its Kronecker's delta property, enabling direct enforcement of boundary conditions (BC). Unlike original MK method, this approach does not require pre-defining the correlation parameter, which can influence approximation accuracy. The governing equations are derived using Hamilton's principle. A thorough analysis is conducted to understand how the helicoidal layup scheme, geometrical parameters, BC, and the foundation's stiffness parameters influence the critical buckling loads and natural frequencies of BiHLC plates.

Abstract The objective of this research is to present practical solutions for improving structural performance of thin-walled conic polygonal monopoles. The analysis encompasses computational simulations, analytical evaluation, and structural verification of reinforcements for openings and longitudinal folded stiffeners of flat walls. A benchmarked solution is derived from a design involving a 20-sided cold-formed steel polygonal section employed to support telecommunication antennas at a height of 40 meters. The structural verification is performed under the influence of wind loads, with particular attention to the commonly reported basic gust wind speed in Brazil. The conducted analysis encompasses: (i) wind-induced static equivalent dynamic behavior, (ii) parametric elastic buckling analysis, (iii) non-linear finite element analysis of reinforced openings, and (iv) direct strength method (DSM) performance evaluation of stiffened polygonal cross-sections. The importance of combining tailored numerical tools such as the finite strip and finite element methods, as well as wind-induced behavior, is demonstrated through the structural analysis results. In essence, the study's findings reveal the previously overlooked local-distortional buckling interaction in current design guidelines. Moreover, the research demonstrates that incorporating reinforcements and longitudinal stiffeners significantly enhances the flexural capacity of slender structures. Notably, the adoption of a single 4-fold (trapezoid) stiffener shape, per polygonal wall, emerges as a promising effective solution for enhancing the overall flexural capacity. Further full scale experimental structural tests and computational fluid dynamics should be considered for advanced structural analysis and improved design.

Abstract A numerical investigation is performed in this work to evaluate the influence of controlled spoilers on pressure mitigation over low-rise building roofs. Considering that low-rise buildings are susceptible to severe damages caused by wind action, spoilers are utilized along the roof windward edges to reduce the aerodynamic load, which are controlled using PID control techniques. Numerical simulations are carried out using a semi-implicit Characteristic-based Split algorithm, where linear tetrahedral finite elements are employed for spatial discretization in a standard Galerkin procedure. Turbulence modeling is performed using Large Eddy Simulation and the flow fundamental equations are written considering isothermal and incompressible conditions in arbitrary Lagrangian-Eulerian kinematical description to consider the spoiler angular motion. Two and three-dimensional simulations are carried out using a low-rise building model, where the influence of controlled roof spoilers is evaluated. Wind tunnel predictions are utilized to validate the numerical formulation proposed here.

Abstract Accounting for fluid-solid coupling in saturated underwater soils, the scattering problem of underwater tunnel under plane SV-wave incidence is investigated by using the Fourier-Bessel series expansion method of wave function. Numerical examples analyze the effects of incident wave angle, frequency, tunnel burial depth, and porosity on displacement at the water-soil interface and dynamic stress concentration on the tunnel surface. When η=0.5, increasing the incident angle reduces horizontal displacement by up to 39.3%, increases vertical displacement by up to 96.2%, and raises the Dynamic Stress Concentration Factor (DSCF) on the tunnel surface by 65.6%. Porosity shows minimal impact on stress and displacement. As porosity increases, horizontal displacement decreases by up to 2.1%, vertical displacement increases by approximately 1.23%, and DSCF decreases by 1.2%. As incident frequency increases, displacement and stress distributions become more complex, with more pronounced peaks, and troughs. Maximum horizontal displacement increases by 86.4%, and vertical displacement by 91.2%. Displacement and stress concentration are most pronounced above the tunnel under shallow burial conditions. fluidsolid fluid solid soils SVwave SV FourierBessel Fourier Bessel function depth watersoil water soil η05 η 0 5 η=0.5 393 39 3 39.3% 962 96 2 96.2% (DSCF 656 65 6 65.6% 21 1 2.1% 123 23 1.23% 12 1.2% complex peaks troughs 864 86 4 86.4% 912 91 91.2% conditions η0 η=0. 39.3 9 96.2 65.6 2.1 1.23 1.2 8 86.4 91.2 η=0 39. 96. 65. 2. 1. 86. 91. η=

Abstract In this paper, the penetration resistance of 6061 aluminum plates to explosively formed projectiles (EFPs) at the incidence angles of 0°, 15°, 30°, and 45° was studied. The penetration process was roughly divided into three typical stages—the plastic flanging stage of the target, the righting stage of the projectile, and the plug formation stage of the target. Through the energy analysis, the energy consumption of the aluminum plate increased with the increase in the incidence angle during the entire penetration process. Through the microscopic analysis of the perforated wall surface of the aluminum plate, it was found that there were distinct boundaries and differences between the plastic reaming zone and the punching plug fracture zone.. Overall, four kinds of classification modes were proposed for the damage of the aftereffect plate, which provides a method to evaluate the aftereffect of EFP oblique penetration into 6061 aluminum plates.

Abstract To further improve the strike accuracy and penetration power of explosively-formed projectile (EFP) after long-distance flight, a polygonal charge capable of forming EFP with tail fins was designed during the study. A model for calculating the EFP velocity was derived from the effective charge and detonation projection theories with the integration of calculus. The circumferential velocity distributions of EFP formed using polygonal charges were obtained using this model, and the mechanisms underlying the formation of tail fins were elucidated. The feasibility of using this polygonal charge to form tail fin EFP was verified by conducting multi-media soft recovery tests and numerical simulations. Furthermore, the feasibility of forming tail fin EFP using polygonal charges with different numbers of sides and the effects of the structural parameters of a hexagonal charge on the formation of tail fin EFP were investigated by simulation. The ranges of optimal values for the structural parameters of a hexagonal charge capable of forming high-performance tail fin EFPs were determined.

Abstract Based on the inverse piezoelectric effect and other characteristics of piezoelectric ceramics, a new type of piezoelectric variable friction damper is developed, and the output performance test of piezoelectric ceramic actuator and piezoelectric variable friction damper is carried out, and the parametric mechanical model of the damper is established by using Simulink to carry out numerical simulation, and compared and analyzed with the test results. The results of the study show that the simulation and the test present a good regular agreement. With the increment of loading voltage, the displacement deformation and zero-displacement thrust of piezoelectric ceramic actuator are approximately linear with the loading voltage; when the loading voltage is increased by 15V every time, the test value of the output damping force of the damper increases by 259.66N on average step by step, and the simulated value increases by 256.14N step by step, and the damping force has a linearly incremental relationship with the voltage and the slope of the linear increase is 16.434.

Abstract Analytical and computational calibrations and subsequent parametric analyses were performed on the four UHPFRC beams under flexure to estimate their actual shear strength. The computational models were calibrated using different values for the CDP parameters, and a finite element mesh sensitivity study was conducted. These models predicted the experimental behavior satisfactorily, and the analytical model was also able to find the beams’ failure loads and proved to be a simple tool to estimate their behavior. The parametric analysis showed that the current beams did not require stirrups once the UHPFRC had high shear strength, and the maximum shear capacity was accurately determined. strength parameters conducted satisfactorily determined

Abstract The use of simple bar elements in nonlinear structural finite element formulations has the academic advantage of uncoupling element technology issues from the structural phenomena to be observed. In this work, we present a finite element setting for the formulation of different nonlinear material models applied to the transient analysis of trusses. While nonlinear elasticity is considered by studying a Hooke-like linear relationship between different pairs of nonlinear measures of stress and strain, hyperelasticity is formulated using Ogden’s model. Viscoelasticity is introduced using a generalized Kelvin rheological model to account for strain rate effects. The finite kinematics is set in a corotational total Lagrangian description where the virtual work is described using the Second Piola-Kirchhoff and the Green Lagrange measures. Although the derivation is omitted, the consistent tangent moduli are given for all these cases. Numerical problems involving simultaneously different truss models are studied and made available as benchmarks since little comparative data is found in literature. observed trusses Hookelike Hooke like Ogdens Ogden s effects PiolaKirchhoff Piola Kirchhoff omitted cases literature

Abstract For the first time, this article uses higher-order IGA to study the high frequency of the functionally graded sandwich (FGS) square nanoplates with two different skin layers resting on elastic foundations. In this work, the elastic foundations use the Pasternak foundation (PF) model with a two-parameter as a spring stiffness ( k 1) and a shear layer stiffness ( k 2). The observation of small-scale effects in nanoplates is accomplished by incorporating nonlocal elasticity theory (NET) with a higher-order shear deformation theory (HSDT). The governing equation of nanoplates is derived from Hamilton's principle. An extensive parametric investigation has been conducted to illustrate the free vibration characteristics of FGS square nanoplates across both low and high frequency modes, placing a greater emphasis on the analysis of high frequency behaviour. Furthermore, the high eigenmodes and frequencies of the FGS circular/elliptical nanoplates are also added. Therefore, the findings presented here contribute to an improved understanding of the vibrations of FGS nanoplates at high frequencies. time higherorder higher order (FGS work PF (PF twoparameter parameter 1 2. 2 . 2) smallscale small scale NET (NET HSDT. HSDT (HSDT) Hamiltons Hamilton s principle modes behaviour Furthermore circularelliptical circular elliptical added Therefore (HSDT

Abstract This paper presents an enhanced version of the Artificial Rabbit Optimization (ARO) algorithm designed for identifying structural damage in bridge structures. The original ARO draws inspiration from survival observed in wild rabbits. However, it demands a substantial investment of computational time. Therefore, in this paper, the Improved ARO (IARO) algorithm incorporating elements of the Grey Wolf Optimizer (GWO) through hybridization, is employed to deal with optimization problems. The central concept of this approach involves infusing predator-hunting characteristics into the prey-rabbit during the hunting process, thereby enabling more effective predator evasion. The proposed method is evaluated through a series of simulations related to two real bridges: a simple supported beam structure and a steel truss bridge. The results show a significant improvement in accuracy and efficiency in determining structural damage while considering factors such as damage location, severity, and computation time. These findings underscore the potential of the proposed approach for real-world applications in structural health monitoring and damage detection. (ARO structures rabbits However time Therefore IARO (IARO GWO (GWO hybridization problems predatorhunting preyrabbit prey rabbit process evasion bridges location severity realworld world detection

Abstract A damage detection method based on the quadratic correlation function of strain responses (QCoS) and pattern matching degree (PMD) is proposed in the present study. For this method, only QCoS is calculated in time domain by strain responses, and there is no need for modal parameter extraction and analytical model of structures. It is proved that QCoS is the function of modal parameters of structures, such as natural frequency, mode shape and damping ratio. Numerical simulations of a simply supported steel beam are analyzed for illustrating the effect of excitation position, reference point and damage level on QCoS, respectively. The results show that QCoS is sensitive to local damage in the structure and robust to measurement noise. Therefore, QCoSs are used to construct the damage feature vector. The damage detection is performed by comparing the damage feature vectors before and after the structural damage. Three simply supported aluminum beams are tested in the laboratory to demonstrate the effectiveness and practicability of the proposed method. (QCoS PMD (PMD study structures frequency ratio position respectively noise Therefore vector

Abstract This article aims to identify the presence of cracks in slender rotating beams (Euler Bernoulli) from the dynamic behaviour of cracked beams operating at low rotational speeds. For this purpose, the behavioural model of the cracked rotating beam developed by the authors in previous works is shown. The results of the mathematical model developed (natural frequencies) feed a novel meta-heuristic optimisation algorithm based on the survival tactics of rabbits against their predators: Artificial Rabbit Optimization (ARO). The application of this algorithm to the first two natural frequencies of vibration obtained with the analytical model and contrasted in previous works gives rise to the identification of the characteristic parameters of the crack contained in the beams. The estimation of the parameters: position along the beam and crack depth, show a high similarity with the initial data, which allows validating the application of the optimisation algorithm to the identification of cracks in this type of component as a first approach to a health monitoring method for more complex rotating cantilever beam structures. Euler Bernoulli speeds purpose shown metaheuristic meta heuristic predators ARO. ARO . (ARO) depth data structures (ARO

Abstract The main goal of this study is to further expand the ES-MITC3 for analyzing the buckling characteristics of functionally graded porous (FGP) variable thickness (VT) plates with sinusoidal porous distribution. The ES-MITC3 was developed to improve the accuracy of classical triangular elements (Q3) and overcome the locking phenomenon while still ensuring flexibility in discretizing the structural domain of the Q3. The first-order shear deformation theory (FSDT) in combination with ES-MITC3 is used due to its simplicity and effectiveness. The Pasternak foundation (PF) is a two-parameter model with springer stiffness ( k 1) and shear stiffness ( k 2) that describes the foundation reaction as a function of the deflection and its Laplacian. The accuracy and performance of the proposed formulation are verified through comparative examples. Moreover, a comprehensive analysis has been undertaken to scrutinize the effects of geometric parameters and material properties on the buckling of FGP VT plates. ESMITC3 ESMITC ES MITC3 MITC ES-MITC (FGP (VT distribution Q3 Q (Q3 firstorder first order FSDT (FSDT effectiveness PF (PF twoparameter two parameter 1 2 Laplacian examples Moreover (Q