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CONTENTS
Volume 70, Number 5, June10 2019
 

Abstract
This study proposed an improved particle swarm optimization (IPSO) method ensemble with kriging model for model updating. By introducing genetic algorithm (GA) and grouping strategy together with elite selection into standard particle optimization (PSO), the IPSO is obtained. Kriging metamodel serves for predicting the structural responses to avoid complex computation via finite element model. The combination of IPSO and kriging model shall provide more accurate searching results and obtain global optimal solution for model updating compared with the PSO, Simulate Annealing PSO (SimuAPSO), BreedPSO and PSOGA. A plane truss structure and ASCE Benchmark frame structure are adopted to verify the proposed approach. The results indicated that the hybrid of kriging model and IPSO could serve for model updating effectively and efficiently. The updating results further illustrated that IPSO can provide superior convergent solutions compared with PSO, SimuAPSO, BreedPSO and PSOGA.

Key Words
model updating; kriging metamodel; improved particle swarm optimization; elite selection; global best solution

Address
Shiqiang Qin, Jia Hu, Yazhou Zhang and Juntao Kang: School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China
Yun-Lai Zhou: Department of Civil and Environmental Engineering, National University of Singapore, 2 Engineering Drive 2, 117576, Singapore

Abstract
An analytical research on buckling of simply supported thin plate with variable thickness under bi-axial compression is presented in this paper. Combining the perturbation technique, Fourier series expansion and Galerkin methods, the linear governing differential equation of the plate with arbitrary thickness variation under bi-axial compression is solved and the analytical expression of the critical buckling load is obtained. Based on that, numerical analysis is carried out for the plates with different thickness variation forms and aspect ratios under different bi-axial compressions. Four different thickness variation forms including linear, parabolic, stepped and trigonometric have been considered in this paper. The calculated critical buckling loads and buckling modes are presented and compared with the published results in the tables and figures. It shows that the analytical expressions derived by the theoretical method in this paper can be effectively used for buckling analysis of simply supported thin plates with arbitrary thickness variation, especially for the stepped thickness that used in engineering widely.

Key Words
buckling; thin plate; thickness variation; compression; analytical expressions

Address
Haigui Fan,Zewu Wang and Peiqi Liu: School of Chemical Machinery and Safety Engineering, Dalian University of Technology,
No.2 Linggong Road, Dalian, Liaoning 116023, P.R. China
Zhiping Chen: Institute of Process Equipment, Zhejiang University, 38 Zheda Road, Hangzhou, Zhejiang 310027, P.R. China

Abstract
This study aimed to develop a high-order shear deformation theory to predict the free vibration of hybrid cross-ply laminated plates under different boundary conditions. The equations of motion for laminated hybrid rectangular plates are derived and obtained by using Hamilton\'s principle. The closed-form solutions of anti-symmetric cross-ply and angle-ply laminates are obtained by using Navier\'s solution. To assess the validity of our method, we used the finite element method. Firstly, the analytical and the numerical implementations were validated for an antisymmetric cross-ply square laminated with available results in the literature. Then, the effects of side-to-thickness ratio, aspect ratio, lamination schemes, and material properties on the fundamental frequencies for different combinations of boundary conditions of hybrid composite plates are investigated. The comparison of the analytical solutions with the corresponding finite element simulations shows the good accuracy of the proposed analytical closed form solution in predicting the fundamental frequencies of hybrid cross-ply laminated plates under different boundary conditions.

Key Words
composites; finite element method (FEM); laminates; plate/shell structures; frequency/modal analysis

Address
Boussad Abbès, Fazilay Abbès, Yuming L, Mohammed Amine Benhenni : GRESPI – University of Reims , Campus du Moulin de la Housse BP 1039 - 51687 Reims cedex 2, France.
Belkacem Adim and ahar Hassaine Daouadji: Laboratoire de Géomatique et Développement Durable, University of Tiaret, Algeria

Abstract
In the present study, a suitable mathematical model considering parabolic transverse shear strains for dynamic analysis of laminated composite skew plates under different types of impulse and spatial loads was presented for the first time. The proposed mathematical model satisfies zero transverse shear strain at the top and bottom of the plate. On the basis of the cubic variation of thickness coordinate in in-plane displacement fields of the present mathematical model, a 2D finite element (FE) model was developed including skew transformations in the mathematical model. No shear correction factor is required in the present formulation and damping effect was also incorporated. This is the first FE implementation considering a cubic variation of thickness coordinate in in-plane displacement fields including skew transformations to solve the forced vibration problem of composite skew plates. The effect of transverse shear and rotary inertia was incorporated in the present model. The Newmark-beta scheme was adapted to perform time integration from step to step. The C0 FE formulation was implemented to overcome the problem of C1 continuity associated with the cubic variation of thickness coordinate in in-plane displacement fields. The numerical studies showed that the present 2D FE model predicts the result close to the analytical results. Many new results varying different parameter such as skew angles, boundary conditions, etc. were presented.

Key Words
transient analysis; laminated composite skew plate; impulse

Address
Anish: Department of Civil Engineering, Birla Institute of Technology Mesra, Patna Camus, Patna - 800014, India
Abhay K. Chaubey: Department of Civil Engineering, Koneru Lakshmaiah Education Foundation, Vaddeswaram 522502, India
Satyam Vishwakarma, Ajay Kumar:Department of Civil Engineering, National Institute of Technology Patna, Patna-800005, India
Stanislaw fic and Danuta Barnat-Hunek: Department of Construction, Faculty of Civil Engineering and Architecture, Lublin University of Technology,
Nadbystrzycka 40, Lublin, Poland

Abstract
To analyze the seismic reliability of concrete rectangular liquid storage structures (CRLSSs), assuming that the wall thickness and internal liquid depth of CRLSSs are random variables, calculation models of CRLSSs are established by using the Monte Carlo finite element method (FEM). The principal stresses of the over-ground and buried CRLSSs are calculated under three rare fortification intensities, and the failure probabilities of CRLSSs are obtained. The results show that the seismic reliability increases with the increase of wall thickness, whereas it decreases with the increase of liquid depth. Between the two random factors, the seismic reliability of CRLSSs is more sensitive to the change in wall thickness. Compared with the overground CRLSS, the buried CRLSS has better reliability.

Key Words
concrete rectangular storage structure; seismic reliability; liquid depth; wall thickness

Address
Xuansheng Cheng: Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province,
Lanzhou University of Technology, Lanzhou, 730050, China
Xuansheng Cheng, Peicun He and Dongjiang Yu: Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education,
Lanzhou University of Technology, Lanzhou, 730050, China

Abstract
This paper aims to develop a quasi-3D shear deformation theory for the study of bending, buckling and free vibration responses of functionally graded (FG) sandwich thick plates. For that, in the present theory, both the components of normal deformation and shear strain are included. The displacement field of the proposed model contains undetermined integral terms and involves only four unknown functions with including stretching effect. Using Navier\'technique the solution of the problem is derived for simply supported sandwich plate. Numerical results have been reported, and compared with those available in the open literature were excellent agreement was observed. Finally, a detailed parametric study is presented to demonstrate the effect of the different parameters on the flexural responses, free vibration and buckling of a simply supported sandwich plates.

Key Words
Quasi 3D solution; FG sandwich plate; bending; buckling; vibration; stretching effect

Address
Fatima Achouri, Rabbab Bachir Bouiadjra : Department of Civil Engineering, University Mustapha Stambouli of Mascara, Algeria
Fatima Achouri,Samir Benyoucef, Fouad Bourada, and Abdelouahed Tounsi: Material and Hydrology Laboratory, University of SidiBel Abbes, Faculty of Technology, Algeria
Fouad Bourada: Departement des Sciences et de la Technologie, Centre Universitaire de Tissemsilt, BP 38004 Ben Hamouda, Algeria
Abdelouahed Tounsi: Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
Steel tubular buckling controlled braces are well known as being simple, practical and cost-effective lateral force resisting systems. Although these system features have gained the attention of the researchers over the last decade, steel tubular buckling controlled braces currently have limited application. Indeed, only a few steel tubes tightly encased within each other exist in the steel industry. In this paper, a new and practical design method is proposed in order to better promote the widespeared application for current steel tubular buckling controlled brace applications. In order to reach this goal, a holedadapter made with polyoxymethylene adaptable to all round and square steel sections, was developed to use as infiller. The research program presents designing, producing and displacement controlled cyclic loading tests of a conventional tubular brace and a buckling controlled composite brace. In addition, numerical analysis was carried out to compare the experimental results. As a result of the experimental studies, buckling was controlled up to 0.88 % drift ratio and the energy dissipation capacity of the conventional tubular brace increased 1.46 times due to the proposed design. The main conclusion of this research is that polyoxymethylene is a highly suitable material for the production of steel tubular buckling controlled braces.

Key Words
polyoxymethylene (POM); composite brace; buckling; cyclic loading; finite elements

Address
Department of Civil Engineering, Karadeniz Technical University, Trabzon, Turkey

Abstract
This study presents a comprehensive nonlinear dynamic approach to investigate the linear and nonlinear vibration of sandwich plates fabricated from functionally graded materials (FGMs) resting on an elastic foundation. Higher-order shear deformation theory and Hamilton\'s principle are employed to obtain governing equations. The Runge–Kutta method is employed together with the commercially available mathematical software MAPLE 14 to solve the set of nonlinear dynamic governing equations. Method validity is evaluated by comparing the results of this study and those of previous research. Good agreement is achieved. The effects of temperature change on frequencies are investigated considering various temperatures and various volume fraction index values, N. As the temperature increased, the plate frequency decreased, whereas with increasing N, the plate frequency increased. The effects of the side-to-thickness ratio, c/h, on natural frequencies were investigated. With increasing c/h, the frequencies increased nonlinearly. The effects of foundation stiffness on nonlinear vibration of the sandwich plate were also studied. Backbone curves presenting the variation of maximum displacement with respect to plate frequency are presented to provide insight into the nonlinear vibration and dynamic behavior of FGM sandwich plates.

Key Words
nonlinear vibration; dynamics; sandwich plate; functionally graded materials; frequency analysis; higher order shear deformation theory; Runge-Kutta method

Address
Behzad Mohammadzadeh: 1Department of Landscape Architecture and Rural System Engineering, Seoul National University, Seoul, 08826, South Korea
2Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
Eunsoo Choi and Dongkyun Kim: Department of Civil Engineering, Hongik University, Seoul 04066, Republic of Korea

Abstract
This paper analyzes the non-stationary vibration and super-harmonic resonances in nonlinear dynamic motion of viscoelastic nano-resonators. For this purpose, a new coupled size-dependent model is developed for a plate-shape nanoresonator made of nonlinear viscoelastic material based on modified coupled stress theory. The virtual work induced by viscous forces obtained in the framework of the Leaderman integral for the size-independent and size-dependent stress tensors. With incorporating the size-dependent potential energy, kinetic energy, and an external excitation force work based on Hamilton\'s principle, the viscous work equation is balanced. The resulting size-dependent viscoelastically coupled equations are solved using the expansion theory, Galerkin method and the fourth-order Runge–Kutta technique. The Hilbert–Huang transform is performed to examine the effects of the viscoelastic parameter and initial excitation values on the nanosystem free vibration. Furthermore, the secondary resonance due to the super-harmonic motions are examined in the form of frequency response, force response, Poincare map, phase portrait and fast Fourier transforms. The results show that the vibration of viscoelastic nanosystem is non-stationary at higher excitation values unlike the elastic ones. In addition, ignoring the small-size effects shifts the secondary resonance, significantly.

Key Words
viscoelasticity; non-stationary motion; nonlinear dynamic; super-harmonic resonance; nano-resonator

Address
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran

Abstract
The performance of precast concrete structures is greatly influenced by the behaviour of beam-to-column connections. A single connection may be required to transfer several loads simultaneously so each one of those loads must be considered in the design. A good connection combines practicality and economy, which requires an understanding of several factors; including strength, serviceability, erection and economics. This research work focuses on the performance aspect of a specific type of beam-to-column connection using partly hidden corbel in precast concrete structures. In this study, the results of experimental assessment of the proposed beam-to-column connection in precast concrete frames was used. The purpose of this research is to develop and apply the Extreme Learning Machine (ELM) for moment-rotation prediction of precast beam-tocolumn connections. The ELM results are compared with genetic programming (GP) and artificial neural network (ANN). The reliability of the computational models was accessed based on simulation results and using several statistical indicators.

Key Words
moment-rotation; forecasting; extreme learning machine; precast beam-to-column connection; partly hidden corbel

Address
Nguyen Thoi Trung, Mahdi Shariati: 1Division of Computational Mathematics and Engineering, Institute for Computational Science,
Ton Duc Thang University, Ho Chi Minh City, Vietnam
2Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
Aiyoub Fazli Shahgoli, Yousef Zandi: Department of Civil Engineering, Islamic Azad University, Tabriz Branch, Iran
Karzan Wakil: Research Center, Sulaimani Polytechnic University, Sulaimani 46001, Kurdistan Region, Iraq
Maryam Safa: Institute of Research and Development, Duy Tan University, Da Nang 550000, Viet Nam
Majid Khorami: Universidad UTE, Facultad de Arquitectura y Urbanismo, Calle Rumipamba s/n y Bourgeois, Quito, Ecuador


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