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CONTENTS
Volume 44, Number 5, September10 2022
 

Abstract
Structural design, in general, is developed through trial and error technique which is guided by standards criteria and based on the intuition and experience of the engineer, a context that leads to structural over-dimensioning, with uneconomic solutions. Aiming to find the optimal design, structural optimization methods have been developed to find a balance between cost, structural safety, and material performance. These methods have become a great opportunity in the steel structural engineering domain since they have as their main purpose is weight minimization, a factor directly correlated to the real cost of the structure. Assuming an objective function of minimum weight with stress and displacement constraints provided by Brazilian standards, the present research proposes the sizing optimization and combined approach of sizing and shape optimization, through a software developed to implement the Simulated Annealing metaheuristic algorithm. Therefore, two steel plane frame layouts, each admitting four typical truss geometries, were proposed in order to expose the difference between the optimal solutions. The assessment of the optimal solutions indicates a notable weight reduction, especially in sizing and shape optimization combination, in which the quantity of design variables is increased along with the search space, improving the efficiency of the optimal solutions achieved.

Key Words
optimization; Simulated Annealing; steel; structures; truss-frame; truss

Address
Jéssica M. Bresolin, Zacarias M.C. Pravia and Moacir Kripka: Faculty of Engineering and Architecture, Graduate Program in Civil and Environmental Engineering (PPGEng),
University of Passo Fundo (UPF), Passo Fundo, Rio Grande do Sul, Brazil

Abstract
There are numerous structural details (Longitudinal beam, web plate, U-ribs and I-ribs) in the top and bottom plates of steel box girders, which have significant influences on the longitudinal stress (normal stress) distribution. Clarifying the influence of these structural details on the normal stress distribution is important. In this paper, the ultra-wide steel box girder with large cantilevers of the Jinhai Bridge in China, which is the widest cable-stayed bridge in the world, has been analyzed. A 1:4.5 scale laboratory model of the steel box girder has been manufactured, and the influence of structural details on the normal stress distribution in the top and bottom plates for four different load cases has been analyzed in detail. Furthermore, a threedimensional finite element model has been established to further investigate the influence regularity of structural details on the normal stress. The experimental and finite element analysis (FEA) results have shown that different structural details of the top and bottom plates have varying effects on the normal stress distribution. Notably, the U-ribs and I-ribs of the top and bottom plates introduce periodicity to the normal stress distribution. The period of the influence of U-ribs on the normal stress distribution is the sum of the single U-rib width and the U-rib spacing, and that of the influence of I-ribs on the normal stress distribution is equal to the spacing of the I-ribs. Furthermore, the same structural details but located at different positions, will have a different effect on the normal stress distribution.

Key Words
cable-stayed bridge; finite element analysis; large cantilever; normal stress; structural details; ultra-wide steel box girder

Address
Yu HONG, ShengYu LI:National Engineering Laboratory for Technology of Geological Disaster Prevention in Land Transportation,
Southwest Jiaotong University, Chengdu, 611756, China

Yining WU, Dailing XU and QianHui PU: Department of Civil Engineering, Southwest Jiaotong University, Chengdu, China

Abstract
This paper is first implemented with the bending behavior of three-dimensional functionally graded (3DFG) plates in the framework of level set-based topology optimization (LS-based TO). Besides, due to the suitable properties of the current design domain, the thin-plate spline (TPS) is recognized as a RBF to construct the LS function. The overall mechanical properties of the 3DFG plate are assessed using a power-law distribution scheme via Mori-Tanaka micromechanical material model. The bending response is obtained using the first-order shear deformation theory (FSDT). The mixed interpolation of four elements of tensorial components (MITC4) is also implemented to overcome a well-known shear locking problem when the thickness becomes thinner. The Hamilton-Jacobi method is utilized in each iteration to enforce the necessary boundary conditions. The mathematical formulas are expressed in great detail for the LS-based TO using 3DFG materials. Several numerical examples are exhibited to verify the efficiency and reliability of the current methodology with the previously reported literature. Finally, the influences of FG materials in the optimized design are explained in detail to illustrate the behaviors of optimized structures.

Key Words
FSDT; level set; MITC4; thin-plate spline; three-dimensional functionally graded material; topology optimization

Address
Thanh T. Banh, Nam G. Luu and Dongkyu Lee: Department of Architectural Engineering, Sejong University, Seoul 05006, Republic of Korea

Abstract
Most of the experimental, theoretical, and numerical studies on the stability of functionally graded composites are deterministic, while there are full of complex interactions of variables with an inherently probabilistic nature, this paper presents a non-intrusive framework to investigate the stochastic nonlinear buckling behaviors of porous functionally graded cylindrical shells exposed to inevitable source-uncertainties. Euler-Lagrange equations are theoretically derived based on the three variable refined shear deformation theory. Closed-form solutions for the shell buckling loads are achieved by solving the deterministic eigenvalue problems. The analytical results are verified with numerical results obtained from finite element analyses that are conducted in the commercial software ABAQUS. The non-intrusive framework is completed by integrating the Monte Carlo simulation with the verified closed-form solutions. The convergence studies are performed to determine the effective pseudorandom draws of the simulation. The accuracy and efficiency of the framework are verified with statistical results that are obtained from the first and second-order perturbation techniques. Eleven cases of individual and compound uncertainties are investigated. Sensitivity analyses are conducted to figure out the five cases that have profound perturbative effects on the shell buckling loads. Complete probability distributions of the first three critical buckling loads are completely presented for each profound uncertainty case. The effects of the shell thickness, volume fraction index, and stochasticity degree on the shell buckling load under compound uncertainties are studied. There is a high probability that the shell has non-unique buckling modes in stochastic environments, which should be known for reliable analysis and design of engineering structures.

Key Words
finite element analysis; Monte Carlo simulation; nonlinear buckling analysis; perturbation technique; porous functionally graded shell; uncertainty quantification

Address
Minh-Chien Trinh:1)Department of Civil and Environmental Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea
2)Division of Mechanical System Engineering, Jeonbuk National University, 567, Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do 54896,
Republic of Korea

Seung-Eock Kim:epartment of Civil and Environmental Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, Republic of Korea


Abstract
This paper reports experimental investigation on shear behavior of steel reinforced concrete (SRC) shallow floor beam, where the steel shape is embedded in concrete and the high strength bolts are used to transfer the shear force along the interface between the steel shape and concrete. Six specimens were conducted aiming to provide information on shear performance and explore the shear bearing capacity of SRC shallow floor beams. The effects of the height of concrete slab, the size and the type of the steel section on shear performance of beams were also analyzed in the test. Based on the strut-and-tie model, the shear strength of the SRC shallow floor beam was proposed. Experimental results showed that composite shallow floor beam exhibited satisfactory composite behavior and all of the specimen failed in shear failure. The shear bearing capacity increased with the increasing of height of concrete slab and the size of steel shape, and the bearing capacities of beam specimens with castellated steel shape was slightly lower than those of specimens with H-shaped steel section. Furthermore, the calculations for evaluating the shear bearing capacity of SRC shallow floor beam were verified to be reasonable.

Key Words
experimental study; shear capacity; shear performance; SRC shallow floor beam; strut-and-tie model

Address
Yang Chen:1)Department of Civil Engineering, Shanghai University, Shanghai, 200444, China
2)School of Civil Engineering, Xi

Abstract
In this paper, the equivalent material properties of cellular metamaterials with different types of perforations have been presented using finite element (FE) simulation of tensile test in Abaqus commercial software. To this end, a Representative Volume Element (RVE) has been considered for each type of cellular metamaterial with regular array of circular, square, oval and rectangular perforations. Furthermore, both straight and perpendicular patterns of oval and rectangular perforations have been studied. By applying Periodic Boundary conditions (PBC) on the RVE, the actual behavior of cellular material under uniaxial tension has been simulated. Finally, the effective Young's modulus, Poisson's ratio and mass density of various metamaterials have been presented as functions of relative density of the RVE.

Key Words
effective properties; finite element simulation; metamaterial; RVE; tensile test

Address
Mohammad Reza Barati and Hossein Shahverdi:Department of Aerospace Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran

Abstract
Shear failure in reinforced concrete (RC) structures is very hazardous. This failure is rarely predicted and may occur without any prior signs. Accurate shear strength prediction of the RC members is challenging, and traditional methods have difficulty solving it. This study develops a JAYA-GBRT model based on the JAYA algorithm and the gradient boosting regression tree (GBRT) to predict the shear strength of RC slender beams without stirrups. Firstly, 484 tests are carefully collected and divided into training and test sets. Then, the hyperparameters of the GBRT model are determined using the JAYA algorithm and 10-fold cross-validation. The performance of the JAYA-GBRT model is compared with five well-known empirical models. The comparative results show that the JAYA-GBRT model (𝑅 2 = 0.982, 𝑅𝑀𝑆𝐸 = 9.466 kN, 𝑀𝐴𝐸 = 6.299 kN, u= 1.018, and Cov = 0.116) outperforms the other models. Moreover, the predictions of the JAYA-GBRT model are globally and locally explained using the Shapley Additive exPlanation (SHAP) method. The effective depth is determined as the most crucial parameter influencing the shear strength through the SHAP method. Finally, a Graphic User Interface (GUI) tool and a web application (WA) are developed to apply the JAYA-GBRT model for rapidly predicting the shear strength of RC slender beams without stirrups.

Key Words
gradient boosting regression tree; graphic user interface; jaya algorithm; reinforced concrete slender beam; shear strength; web application

Address
Viet-Linh Tran:1)Department of Civil Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811,
Republic of Korea
2)Department of Civil Engineering, Vinh University, Vinh 461010, Vietnam

Jin-Kook Kim:Department of Civil Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811,
Republic of Korea

Abstract
In the present work, bending and free vibration analyses of multilayered functionally graded (FG) graphene platelet (GPL) and fiber-reinforced hybrid composite beams are carried out using the parabolic function based shear deformation theory. Parabolic variation of transverse shear stress across the thickness of beam and transverse shear stress-free conditions at top and bottom surfaces of the beam are considered, and the proposed formulation incorporates a transverse displacement field. The present theory works only with four unknowns and is computationally efficient. Hamilton's principle has been employed for deriving the governing equations. Analytical solutions are obtained for both the bending and free vibration problems in the present work considering different variations of GPLs and fibers distribution, namely, FG-X, FG-U, FG-A, , and FG-O for beams having simply-supported boundary condition. First, the matrix is assumed to be strengthened using GPLs, and then the fibers are embedded. Multiscale modeling for material properties of functionally graded graphene platelet/fiber hybrid composites (FGGPL/FHRC) is performed using Halpin-Tsai micromechanical model. The study reveals that the distributions of GPLs and fibers have significant impacts on the stresses, deflections, and natural frequencies of the beam. The number of layers and shape factors widely affect the behavior of FG-GPL-FHRC beams. The multilayered FG-GPL-FHRC beams turn out to be a good approximation to the FG beams without exhibiting the stress-channeling effects.

Key Words
hybrid composite; bending; free vibration; graphene platelet/fiber composite; functionally graded material

Address
A. Garg:1)Department of Aerospace Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India - 208016
2)Department of Civil and Environmental Engineering, The NorthCap University, Gurugram, Haryana, India – 122017

T. Mukhopadhyay: Department of Aerospace Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, India - 208016

H.D. Chalak:Department of Civil Engineering, National Institute of Technology Kurukshetra, Kurukshetra, Haryana, India – 136119

M.O. Belarbi:Laboratoire de Recherche en Génie Civil, LRGC. Université de Biskra B.P. 145, R.P. 07000, Biskra, Algeria

L. Li:State Key Laboratory of Digital Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong
University of Science and Technology, Wuhan 430074, China

R. Sahoo: Department of Civil Engineering, Indian Institute of Technology (BHU) Varanasi, Varanasi, Uttar Pradesh, India - 221005

Abstract
In this paper, an accurate kinematic model has been developed to study the mechanical response of functionally graded (FG) sandwich beams, mainly covering the bending, buckling and free vibration problems. The studied structure with homogeneous hardcore and softcore is considered to be simply supported in the edges. The present model uses a new refined shear deformation beam theory (RSDBT) in which the displacement field is improved over the other existing high-order shear deformation beam theories (HSDBTs). The present model provides good accuracy and considers a nonlinear transverse shear deformation shape function, since it is constructed with only two unknown variables as the Euler-Bernoulli beam theory but complies with the shear stress-free boundary conditions on the upper and lower surfaces of the beam without employing shear correction factors. The sandwich beams are composed of two FG skins and a homogeneous core wherein the material properties of the skins are assumed to vary gradually and continuously in the thickness direction according to the power-law distribution of volume fraction of the constituents. The governing equations are drawn by implementing Hamilton's principle and solved by means of the Navier

Key Words
bending; buckling; FG sandwich beams; free vibration; kinematic model; RSDBT

Address
Fethi Mouaici: 1)Department of Civil Engineering, Faculty of Technology, University of Blida1, Algeria 2)Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria

Abed Bouadi: Department of Physics, University of Science and Technology of Oran (USTO), 31024, Oran, Algeria

Mohamed Bendaida: Laboratoire de Modélisation et Simulation Multi-Echelle, Université de Sidi Bel Abbés, Algeria

Kada Draiche:1) 2Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria 2)Department of Civil Engineering, University Ibn Khaldoun Tiaret, BP 78 Zaaroura, 14000 Tiaret, Algeria

Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-Echelle, Université de Sidi Bel Abbés, Algeria

Fouad Bourada:1) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria 2) Département des Sciences et de la Technologie, université de Tissemsilt, BP 38004 Ben Hamouda, Algérie

Abdelouahed Tounsi:1) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria 7)YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea 8)Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Mofareh Hassan Ghazwani: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Kingdom of Saudia Arabia

Ali Alnujaie: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Kingdom of Saudia Arabia


Abstract
Earlier works have shown that excessive shear stiffness at the steel-concrete interface causes a non-uniform distribution of shear force in composite structures. When the shear studs are wrapped at the fixed end with flexible materials with a low elastic modulus, the shear stiffness at the interface is reduced. The objective of this study was to investigate the effect of silicone rubber-sleeve mounted on shear studs on the shear stiffness of steel-concrete composite structures. Eighteen push-out tests were conducted to investigate the mechanical behavior of silicone rubber-sleeved shear stud groups (SRS-SSG). The dimension and arrangement of silicon rubber-sleeves (SRS) were taken into consideration. Test results showed that the shear strength of SRS-SSG was higher than that of a shear stud group (SSG), without SRS. For SRS-SSG with SRS heights of 50 mm, 100 mm, 150 mm, the shear strengths were improved by 13%, 20% and 9%, respectively, compared to the SSG alone. The shear strengths of SRS-SSG with the SRS thickness of 2 mm and 4 mm were almost the same. The shear stiffness of the SRS-SSG specimens with SRS heights of 50 mm, 100 mm and 150 mm were 77%, 67% and 66% of the SSG specimens, respectively. Test results of specimens SSG-1 and predicted values based on the three design specifications were compared. The nominal single stud shear strength of SSG-1 specimens was closest to that calculated by the Chinese Code for Design of Steel Structures (GB50017-2017). An equation is proposed to consider the effects of SRS for GB50017-2017, and the predicted values based on the proposed equation agree well with the tested results of SRS-SSG.

Key Words
push-out tests; shear stiffness; shear strength; shear studs; silicone rubber-sleeved shear stud groups

Address
Chang Yang and Decan Yang: Department of Road and Bridge Engineering, Wuhan University of Technology, 1178 Heping Ave, Wuhan 430063, China

Caiping Huang and Zhixiang Huang:Department of Road and Bridge Engineering, Hubei University of Technology, 28 Nanli Road, Wuhan 430068, China

Lizhi Ouyang: Department of Physics and Mathematics, Tennessee State University, 3500 John A. Merritt Boulevard, Nashville TN 37209, USA

Landon Onyebueke: Department of Mechanical and Manufacturing Engineering, Tennessee State University,
3500 John A. Merritt Boulevard, Nashville TN 37209, USA

Lin Li: Department of Civil and Architectural Engineering, Tennessee State University, 3500 John A. Merritt Boulevard, Nashville TN 37209, USA

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