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CONTENTS
Volume 43, Number 1, April10 2022
 

Abstract
The free and forced nonlinear dynamic behaviors of Porous Functionally Graded Material (PFGM) plates are examined by means of a High-Order Implicit Algorithm (HOIA). The formulation is developed using the Third-order Shear Deformation Theory (TSDT). Unlike previous works, the formulation is written without resorting to any homogenization technique neither rule of mixture nor considering FGM as a laminated composite, and the distribution of the porosity is assumed to be gradually variable through the thickness of the PFGM plates. Using the Hamilton principle, we establish the governing equations of motion. The Finite Element Method (FEM) is used to compute approximations of the resulting equations; FEM is adopted using a four-node quadrilateral finite element with seven Degrees Of Freedom (DOF) per node. Nonlinear equations are solved by a HOIA. The accuracy and the performance of the proposed approach are verified by presenting comparisons with literature results for vibration natural frequencies and dynamic response of PFGM plates under external loading. The influences of porosity volume fraction, porosity distribution, slenderness ratio and other parameters on the vibrations of PFGM plate are explored. The results demonstrate the significant impact of different physical and geometrical parameters on the vibration behavior of the PFGM plate.

Key Words
finite element method; free vibration; high-order implicit algorithm; nonlinear dynamics; porous functionally graded material

Address
Mohamed Janane Allah, Abdelaziz Timesli and Youssef Belaasilia:Hassan II University of Casablanca, National Higher School of Arts and Crafts (ENSAM CASABLANCA),
AICSE Laboratory, 20670 Casablanca, Morocco

Abstract
The static strength and fatigue crack resistance of the aircraft skin structures depend on the materials used and joint type. Most of the commercial aircraft's skin panel structures are made from aluminium alloy and carbon fibre reinforced epoxy. In this study, the fatigue resistance of four joint configurations (metal/metal, metal/composite, composite/composite and composite/metal) with riveted, adhesive bonded, and hybrid joining techniques are investigated with experiments and finite element analysis. The fatigue tests were tension-tension because of the typical nature of the loads on aircraft skin panels susceptible of experimenting fatigue. Experiment results suggest that the fatigue life of hybrid joints is superior to adhesive bonded joints, and these in turn much better than conventional riveted joints. Thanks to the fact that, for hybrid joints, the adhesive bond provides better load distribution and ensures load-carrying capacity in the event of premature adhesive failure while rivets induce compressive residual stresses in the joint. Results from FE tool ABAQUS analysis for adhesive bonded and hybrid joints agrees with the experiments. From the analysis, the energy release rate for adhesive bonded joints is higher than that of hybrid joints in both opening (mode I) and shear direction (mode II). Most joints show higher energy release rate in mode II. This indicates that the joints experience fatigue crack in the shear direction, which is responsible for crack opening.

Key Words
adhesive bond; aluminium alloy; composite; fatigue; finite element; joints; rivets

Address
Siddharth Pitta:Department of Physics, Division of Aerospace Engineering, Universitat Politècnica de Catalunya,
c/ Esteve Terradas 5, 08860, Castelldefels, Spain

Jose I. Rojas:Department of Physics, Division of Aerospace Engineering, Universitat Politècnica de Catalunya,
c/ Esteve Terradas 5, 08860, Castelldefels, Spain

Francesc Roure:Department of Strength of Materials and Structural Engineering, Universitat Politècnica de Catalunya,
Av. Diagonal 647, 08028, Barcelona, Spain

Daniel Crespo:Department of Physics and Barcelona Research Centre in Multiscale Science and Technology,
Av. Eduard Maristany 16, 08019, Barcelona, Spain

Magd Abdel Wahab: 1)Faculty of Mechanical, Electrical and Computer Engineering, School of Engineering and Technology,
Van Lang University, Ho Chi Minh City, Vietnam
2) Soete Laboratory, Faculty of Engineering and Architecture, Ghent University, Technologiepark Zwijnaarde 903, B-9052, Zwijnaarde, Belgium

Abstract
This paper is concerned with the buckling behavior of functionally graded graphene reinforced porous nanocomposite beams based on the finite element method (FEM) using two variables trigonometric shear deformation theory. Both Young's modulus and material density of the FGP beam element are simultaneously considered as grading through the thickness of the beam. The finite element approach is developed using a nonlocal strain gradient theory. The governing equations derived here are solved introducing a 3-nodes beam element, and then the critical buckling load is calculated with different porosity distributions and GPL dispersion patterns. After a convergence and validation study to verify the accuracy of the present model, a comprehensive parametric study is carried out, with a particular focus on the effects of weight fraction, distribution pattern of GPL reinforcements on the Buckling behavior of the nanocomposite beam. The effects of various structural parameters such as the dispersion patterns for the graphene and porosity, thickness ratio, boundary conditions, and nonlocal and strain gradient parameters are brought out. The results indicate that porosity distribution and GPL pattern have significant effects on the response of the nanocomposite beams, and the results allows to identify the most effective way to achieve improved buckling behavior of the porous nanocomposite beam.

Key Words
buckling; finite element method; functionally graded porous materials; nonlocal strain gradient theoryariational formulation

Address
Lahcene Fortas:MN2I2S Laboratory, Faculty of Science and Technology, Biskra University, Biskra, Algeria

Abderraouf Messai:University Ferhat Abbas SETIF 1, Department of Civil Engineering, SETIF, Algeria

Tarek Merzouki:LISV, University of Versailles Saint-Quentin, 10-12 avenue de l

Abstract
To develop high-efficiency lateral force resistance components for high-rise buildings, a novel energy dissipation shear wall with concrete-filled steel tubular (CFST) column elements was proposed. An energy dissipation shear wall specimen with CFST column elements (GZSW) and an ordinary reinforced concrete shear wall (SW) were constructed, and experimented by low-cycle reversed loading. The mechanical characteristics of these two specimens, including the bearing capacity, ductility, energy dissipation, and stiffness degradation process, were analyzed. The finite-element model of the GZSW was established by ABAQUS. Based on this finite-element model, the effect of the placement of steel-plate energy dissipation connectors on the seismic performance of the shear wall was analyzed, and optimization was performed. The experiment results prove that, the GZSW exhibited a superior seismic performance in terms of bearing capacity, ductility, energy dissipation, and stiffness degradation, in comparison with the SW. The results calculated by the ABAQUS finite-elements model of GZSW corresponded well with the results of experiment, and it proved the rationality of the established finite-elements model. In addition, the optimal placement of the steel-plate energy dissipation connectors was obtained by ABAQUS.

Key Words
CFST column elements; finite-element; rubber energy dissipation belts; seismic performance; shear wall; steel-plate energy dissipation connectors

Address
Hao Su:School of Civil Engineering, Xi'an University of Architecture and Technology, No.13, Yanta Road, Xi'an, Shaanxi, China

Lihua Zhu:1) School of Civil Engineering, Xi'an University of Architecture and Technology, No.13, Yanta Road, Xi'an, Shaanxi, China 2) Key Lab of Structural Engineering and Earthquake Resistance, Ministry of Education
(Xi'an University of Architecture and Technology), No.13, Yanta Road, Xi'an, Shaanxi, China

Yaohong Wang:School of Civil Engineering, Inner Mongolia University of Technology, No.49, Aimin Street, Hohhot, Inner Mongolia, China

Lei Feng:Inner Mongolia Power (GROUP) Co., Ldt, Hohhot, Inner Mongolia, China

Zeyu Gao:Dongtai Municipal Education Bureau, Dongtai, Jiangsu, China

Yuchen Guo:6School of Highway, Chang'an University, Xi'an, Shaanxi, China

Longfei Meng:School of Civil Engineering, Xi'an University of Architecture and Technology, No.13, Yanta Road, Xi'an, Shaanxi, China

Hanquan Yuan:School of Civil Engineering, Xi'an University of Architecture and Technology, No.13, Yanta Road, Xi'an, Shaanxi, China

Abstract
In the current study, ordinary design of Represstessed Pre-Flex (RPF) girder by classical beam theory and numerical model taking buckled shape into consideration were compared with field-survey data to find imperfections on the RPF girder before prestressing and after preflexion. It should be noted that the ordinary design do not consider deformed shape of steel girder in RPF beam. The deformed shapes of steel girder due to the incomplete fabrication that could be caused by self-weight, preflexion misalignment, existence of lateral bracing at mid-span and stiffness of reaction frame were found using a newly developed model which was verified against a deformation survey conducted on actual RPF girder in the field. The final observed deformed shapes of RPF after concrete shrinkage and before prestressing were classified into W, C and Unsymmetric shapes in regard to both survey and analytical results. The deformation survey showed negligible amount of unwanted deformation compared to the large size of the RPF girders. The shallower width of the bottom flange of steel girder caused amount of lateral torsional buckling under self-weight and preflexion thereby affecting the unwanted final overall shape of the RPF girders. However, it was found that the unwanted deformation of RPF girders by fabrication errors even though it is negligible compared to the size of the girder, caused unsymmetrical stress contours in concrete and additional tensile stress and raise some safety issues.

Key Words
buckling; preflex girder; preflexion; shallow bottom flange; shrinkage

Address
Euisuk Jeong:Dept. of Civil and Environmental Engineering, South Dakota State Univ., Box 2219 University Station, Brookings, SD, USA

Hwan-Woo Lee:Department of Civil Engineering, Pukyong National University, Daeyeondong, Namgu, Busan, Korea

Jaeha Lee:1) Major of Civil Engineering, Korea Maritime and Ocean University,727 Taejong-ro, Yeongdo-Gu, Busan, Korea
2) Interdisciplanry Major of Ocean Renewable Energy Engineering, Korea Maritime and Ocean University,
727 Taejong-ro, Yeongdo-Gu, Busan, Korea

Abstract
In this study, the dynamic behavior of functionally graded layered deep beams with viscoelastic core is investigated including the porosity effect. The material properties of functionally graded layers are assumed to vary continuously through thickness direction according to the power-law function. To investigate porosity effect in functionally graded layers, three different distribution models are considered. The viscoelastically cored deep beam is exposed to harmonic sinusoidal load. The composite beam is modeled based on plane stress assumption. The dynamic equations of motion of the composite beam are derived based on the Hamilton principle. Within the framework of the finite element method (FEM), 2D twelve –node plane element is exploited to discretize the space domain. The discretized finite element model is solved using the Newmark average acceleration technique. The validity of the developed procedure is demonstrated by comparing the obtained results and good agreement is detected. Parametric studies are conducted to demonstrate the applicability of the developed methodology to study and analyze the dynamic response of viscoelastically cored porous functionally graded deep beams. Effects of viscoelastic parameter, porosity parameter, graduation index on the dynamic behavior of porous functionally graded deep beams with viscoelastic core are investigated and discussed. Material damping and porosity have a significant effect on the forced vibration response under harmonic excitation force. Increasing the material viscosity parameters results in decreasing the vibrational amplitudes and increasing the vibration time period due to increasing damping effect. Obtained results are supportive for the design and manufacturing of such type of composite beam structures.

Key Words
different porosity models; dynamic behavior; finite element method; porous functionally graded deep beam; viscoelastic core

Address
Amr Assie:1)Mechanical Engineering Department, Faculty of Engineering, Jazan University, P. O. Box 45142, Jazan, Kingdom of Saudi Arabia 2) Mechanical Design & Production Department, Faculty of Engineering, Zagazig University,P.O. Box 44519, Zagazig, Egypt

Şeref D. Akbaş:Department of Civil Engineering, Bursa Technical University, 16330, Bursa, Turkey

Abdallah M. Kabeel:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Kabeel, Alaa A. Abdelrahma:Mechanical Design & Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Mohamed A. Eltaher: 1) Mechanical Design & Production Department, Faculty of Engineering, Zagazig University,P.O. Box 44519, Zagazig, Egypt 2)Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia

Abstract
This paper has focused on presenting a three dimensional theory of elasticity for free vibration of 3D-graphene foam reinforced polymer matrix composites (GrF-PMC) cylindrical panels resting on two-parameter elastic foundations. The elastic foundation is considered as a Pasternak model with adding a Shear layer to the Winkler model. The porous graphene foams possessing 3D scaffold structures have been introduced into polymers for enhancing the overall stiffness of the composite structure. Also, 3D graphene foams can distribute uniformly or non-uniformly in the shell thickness direction. The effective Young's modulus, mass density and Poisson's ratio are predicted by the rule of mixture. Three complicated equations of motion for the panel under consideration are semi-analytically solved by using 2-D differential quadrature method. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. Because of using twodimensional generalized differential quadrature method, the present approach makes possible vibration analysis of cylindrical panels with two opposite axial edges simply supported and arbitrary boundary at the curved edges. It is explicated that 3D-GrF skeleton type and weight fraction can significantly affect the vibrational characteristics of GrF-PMC panel resting on twoparameter elastic foundations.

Key Words
2-D differential quadrature method; 3D-GrF; cylindrical panel; natural frequency; Polymer matrix composite (PMC); three-dimensional theory of elasticity; two-parameter elastic foundation

Address
Li-Cai Zhao:1) Department of Civil and Construction Engineering, National Taiwan University of Science and Technology,
No.43, Keelung Road, Sec.4, Taipei 106, Taiwan 2)School of Civil Engineering, Tianjin University, Tianjin 300072, China
3)China Railway 19th Bureau Group Third Engineering Co., Ltd., Shenyang 110136, China

Shi-Shuenn Chen:Department of Civil and Construction Engineering, National Taiwan University of Science and Technology,No.43, Keelung Road, Sec.4, Taipei 106, Taiwan

Mohammad Khajehzadeh:Department of Civil Engineering, Anar Branch, Islamic Azad University, Anar, Iran

Mariwan Araz Yousif:Department of Architectural Engineering, Cihan University-Erbil, kurdistan region, Iraq

Vahid Tahouneh:Young Researchers and Elite Club, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran

Abstract
This paper presents results of numerical studies completed on unreinforced and doubler plate reinforced Elliptical Hollow Section (EHS) T-joints subjected to axial compressive loading on the brace member. Non-linear finite element (FE) models were developed using the finite element code, ABAQUS. Available test data in literature was used to validate the FE models. Subsequently, a parametric study was carried out to investigate the effects of various geometrical parameters of main members and reinforcement plates on the ultimate capacity of reinforced EHS T-joints. The parametric study found that the reinforcing plate significantly increases the ultimate capacity of EHS T-joints up to twice the capacity of the corresponding unreinforced joint. The thickness and length of the reinforcing plate have a positive effect on the ultimate capacity of Type 1 joints. This study, however, found that the capacity of Type 1 orientation is not dependent on the brace-to-chord diameter ratio. As for type 2 orientations, the thickness and length of the reinforcement have a minimal effect on the ultimate capacity. A new design method is introduced to predict the capacity of the reinforced EHS T-joints Type 1 and 2 based on the multiple linear regression analyses.

Key Words
doubler plate; finite element analyses; elliptical hollow section; tubular joints; ultimate capacity

Address
Busra Sari and Emre Ozyurt: Department of Civil Engineering, Gumushane University, Gumushane, Turkey

Abstract
This study investigates the wave propagation in porous functionally graded (FG) sandwich plates subjected to hygrothermal environments. A new simple three-unknown first-ordershear deformation theory (FSDT) incorporating an integral term is utilized in this paper. Only three unknowns are used to formulate the governing differential equation by applying the Hamilton principle. The FG layer of the sandwich plate is modeled using the power-law function with evenly distributed porosities to represent the defects of the manufacturing process. The plate is subjected to nonlinear hygrothermal changes across the thickness. The effects of the power-law exponent, core to thickness ratios, porosity volume, and the relations between volume fraction and wave properties of porous FG plate under the hygrothermal environment are investigated. The results showed that the waves'phase velocities increase linearly with the waves number in the FGM plate. The porosity of the FG materials plate has a noticeable impact on the phase velocity when considering the high ratios of the core layer. It has a negligible effect on small core layers. Finally, it is observed that changing temperatures and moistures do not influence the relationship between the power law and the phase velocity.

Key Words
FG sandwich plates; hygrothermal environment; porosity; three-variable FSDT; wave propagation

Address
Mohammed A. Al-Osta:1)Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
2)Interdisciplinary Research Center for Construction and Building Materials, KFUPM, 31261 Dhahran, Saudi Arabia

Abstract
Dynamic response of a laminated porous concrete beam reinforced by nanoparticles subjected to harmonic transverse dynamic load is investigated considering structural damping. The effective nanocomposite properties are evaluated on the basis of Mori-Tanaka model. The concrete beam is modeled by the sinusoidal shear deformation theory (SSDT). Utilizing nonlinear strains-deflection, energy relations and Hamilton's principal, the governing final equations of the concrete laminated beam are calculated. Utilizing differential quadrature method (DQM) as well as Newmark method, the dynamic displacement of the concrete laminated beam is discussed. The influences of porosity parameter, nanoparticles volume percent, agglomeration of nanoparticles, boundary condition, geometrical parameters of the concrete beam and harmonic transverse dynamic load are studied on the dynamic displacement of the laminated structure. Results indicated that enhancing the nanoparticles volume percent leads to decrease in the dynamic displacement about 63%. In addition, with considering porosity of the concrete, the dynamic displacement enhances about 2.8 time.

Key Words
DQM; dynamic response; laminated concrete porous beam; nanoparticles; newmark method

Address
Mohammad Karegar:Department of Civil Engineering, Khomein Branch, Islamic Azad University, Khomein, Iran

Mahmood Rabani Bidgoli:1)Department of Civil Engineering, Khomein Branch, Islamic Azad University, Khomein, Iran 2) Department of Civil Engineering, Jasb Branch, Islamic Azad University, Jasb, Iran

Hamid Mazaheri:Department of Civil Engineering, Khomein Branch, Islamic Azad University, Khomein, Iran

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