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Abstract
In this study size optimization of large-scale dome structures with dynamic constraints is presented. In the optimal design of these structure, the Jaya algorithm is used to find minimal size of design variables. The design variables are the cross-sectional areas of the steel truss bar elements. To take into account the constraints which are the first five natural frequencies of the structures, the finite element analysis is coded in Matlab programs using eigen values of the stiffness matrix of the dome structures. The Jaya algorithm and the finite elements codes are combined by the help of the Matlab - GUI (Graphical User Interface) programming to carry out the optimization process for the dome structures. To show the efficiency and the advances of the Jaya algorithm, 1180 bar dome structure and the 1410 bar dome structure were tested by taking into the frequency constraints. The optimal results obtained by the proposed algorithm are compared with those given in the literature to demonstrate the performance of the Jaya algorithm. At the end of the study, it is concluded that the proposed algorithm can be effectively used in the optimal design of large-scale dome structures.

Key Words
Jaya; optimization; finite element analysis; dynamic analysis; dome structure; large-scale structure

Address
Tayfun Dede: Karadeniz Technical University, Department of Civil Engineering, Trabzon, Turkey Maksym Grzywiński and Jacek Selejdak: Czestochowa University of Technology, Faculty of Civil Engineering, 42200 Czestochowa, Poland

Abstract
This paper is aimed to address a simultaneous optimization of the size, shape, and topology of steel lattice towers through a combination of the radial basis function (RBF) neural networks and the artificial bee colony (ABC) metaheuristic algorithm to reduce the computational time because mere metaheuristic optimization algorithms require much time for calculations. To verify the results, use has been made of the CIGRÉ Tower and a 132 kV transmission towers as numerical examples both based on the design requirements of the ASCE10-97, and the size, shape, and topology have been optimized (in both cases) once by the RBF neural network and once by the MSTOWER analyzer. A comparison of the results shows that the neural network-based method has been able to yield acceptable results through much less computational time.

Key Words
optimization; power transmission towers; steel lattice towers; RBF neural network; artificial bee colony (ABC) algorithm

Address
Faezeh Taheri, Mohammad Reza Ghasemi: Department of Civil Engineering, University of Sistan and Baluchestan, Zahedan, Iran Babak Dizangian: Department of Civil Engineering, Velayat University, Iranshahr, Iran

Abstract
This paper deals with the buckling and optimization of a nanocomposite beam. The agglomeration of nanoparticles was assumed by Mori-Tanaka model. The harmony search optimization algorithm is adaptively improved using two adjusted processes based on dynamic parameters. The governing equations were derived by Timoshenko beam model by energy method. The optimum conditions of the nanocomposite beam- based proposed AIHS are compared with several existing harmony search algorithms. Applying DQ and Hs methods, the optimum values of radius and FS were obtained. The effects of thickness, agglomeration, volume percent of CNTs and boundary conditions were assumed. The results show that with increasing the volume percent of CNTs, the optimum radius of the beam decreases while the FS was improved.

Key Words
harmony search; buckling; optimization nanocomposite beam; nanoparticles

Address
Mohsen Motezaker: School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran Arameh Eyvazian: Mechanical and Industrial Engineering Department, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar

Abstract
In the present work, the optimization of machining parameters to achieve the desired technological parameters such as surface roughness, tool radial vibration and material removal rate have been carried out using response surface methodology (RSM). The hard turning of EN19 alloy steel with coated carbide (GC3015) cutting tools was studied. The main problem faced in manufacturer of hard and high precision components is the selection of optimum combination of cutting parameters for achieving required quality of surface finish with maximum production rate. This problem can be solved by development of mathematical model and execution of experiments by RSM. A face centred central composite design (FCCD), which comes under the RSM approach, with cutting parameters (cutting speed, feed rate and depth of cut) was used for statistical analysis. A second-order regression model were developed to correlate the cutting parameters with surface roughness, tool vibration and material removal rate. Consequently, numerical and graphical optimization were performed to obtain the most appropriate cutting parameters to produce the lowest surface roughness with minimal tool vibration and maximum material removal rate using desirability function approach. Finally, confirmation experiments were performed to verify the pertinence of the developed mathematical models.

Key Words
hard turning; optimization; mathematical model; surface roughness; tool vibration

Address
Mohamed Walid Azizi, Ouahid Keblouti, Lakhdar Boulanouar: Advanced Technologies in Mechanical Production Research Laboratory (LRTAPM), Badji Mokhtar - Annaba University, P.O Box 12, 23000 Annaba, Algeria Mohamed Walid Azizi: Technical Science Department, Abdelhafid Boussouf-Mila University Center, 43000, Algeria Mohamed Athmane Yallese: Mechanics and Structures Research Laboratory (LMS), May 8th 1945 University, P.O. Box 401, Guelma 24000, Algeria

Abstract
This study presents a practical application of topology optimization (TO) technique to seek the best form of perforated steel plate shear walls (PSPSW) in simple frames. For the numerical investigation, a finite element model is proposed based on the recent particular form of PSPSW that is called the ring-shaped steel plate shear wall. The TO is applied based on the sensitivity analysis to maximize the reaction forces as the objective function considering the fracture tendency. For this purpose, TO is conducted under a monotonic and cyclic loading considering the nonlinear behavior (material and geometry) and buckling. Also, the effect of plate thickness is studied on the TO results. The final material volume of the optimized plate is limited to the material volume of the ring-shaped plate. Finally, an optimized plate is introduced and its nonlinear behavior is investigated under a cyclic and monotonic loading. For a more comprehensive view, the results are compared to the ring-shaped and four usual forms of SPSWs. The material volume of the plate for all the models is the same. The results indicate the strength, load-carrying, and energy dissipation in the optimized plate are increased while the fracture tendency is reduced without changing the material volume.

Key Words
topology optimization; perforated steel plate shear walls; simple frame; cyclic loading; sensitivity analysis

Address
Faculty of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran

Abstract
A floating dry dock is an advanced structure that can provide a solution for dry dock space shortages. The critical point in floating dock operation is compensating the deflection caused by a heavy payload by adjusting the water level in the ballast system. An appropriate ballasting plan warrants safe and precise construction on a floating dock. Particularly, in the case of a 2D floating dock, ballasting plan evaluation is crucial due to complex deformation modes. In this paper, we developed a method to calculate the optimal ballasting plan for accurate and precise construction on a 2D floating dock. The finite element method was used for considering the flexibility of the floating dock as well as the construction blocks. Through a gradient-based optimization algorithm, the optimal ballasting plan for the given load condition was calculated in semi-real time (5 min). The present method was successfully used for the actual construction of an offshore structure on the 2D floating dock.

Key Words
floating dock; offshore structure; finite element model; optimization; ballasting plan

Address
Kyungho Yoon, Hyo-Jin Kim, Seungkyun Yeo: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291, Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea Younghwa Hong, Jihye Cha: Institute of Industrial Technology, Samsung Heavy Industries, 217, Munji-ro, Yuseong-gu, Daejeon 34051, Republic of Korea Hyun Chung: Department of Naval Architecture & Ocean Engineering, Chungnam National University, 99, Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea

Abstract
Nowadays, composite plates are widely used as high-strength structures to fabricate a dynamic loading-resistant armours. In this study, the shock load is applied by an explosion of spherical TNT charge at a specified distance from the circular composite plate. The composite plate contains a two-layer ceramic-metal armour and a poly-methyl methacrylate (PMMA) target layer. The dynamic behavior of the composite armour has been investigated by measuring the transferred effective stress and maximum deflection into the target layer. For this purpose, the simulation of the blast loading upon the composite structure was performed by using the load-blast enhanced (LBE) procedure in Ls-Dyna software. The effect of main process parameters such as the thickness of layers, and scaled distance has been examined on the specific stiffness of the structure using response surface method. After validating the results by comparing with the experimental results, the optimal values for these parameters along with the regression equations for transferred effective stress and displacement to the target have been obtained. Finally, the optimal values of input parameters have been specified to achieve minimum transferred stress and displacement, simultaneously with reducing the weight of the structure.

Key Words
shock wave; composite armour; ceramic-metal; optimization; response surface method

Address
Mohammad Javad Rezaei, Mahdi Gerdooei: Faculty of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran Hasan Ghaforian Nosrati: Department of Mechanical Engineering, Esfarayen University of Technology, Esfarayen, North Khorasan, Iran

Abstract
The preservation of historic masonry-arch railway bridges is of paramount importance due to their economic benefits. These bridges which belong to past centuries may nowadays be expected to carry loads higher than those for which they were designed. Such an increase in loads may be because of increase in transportation speed or in the capacity of freight-wagons. Anyway, adequate increase in their load-carrying-capacity through structural-strengthening is required. Moreover, the increasing costs of material/construction urge engineers to optimize their designs to obtain the minimum-cost one. This paper proposes a novel numerical optimization method to minimize the costs associated with strengthening of masonry-arch railway bridges. To do so, the stress/displacement responses of Sahand-Goltappeh bridge are assessed under ordinary train pass as a case study. For this aim, 3D-Finite-Element-Model is created and calibrated using experimental test results. Then, it is strengthened such that following goals are achieved simultaneously: (1) the load-carrying-capacity of the bridge is increased; (2) the structural response of the bridge is reduced to a certain limit; and, (3) the costs needed for such strengthening are minimized as far as possible. The results of the case study demonstrate the applicability/superiority of the proposed approach. Some economic measures are also recommended to further reduce the total strengthening cost.

Key Words
numerical optimization; arch bridge; cost minimization; railway network; structural strengthening; train speed

Address
Department of Civil Engineering, University of Maragheh, Maragheh, Iran

Abstract
Structural damage identification (SDI) is a crucial step in structural health monitoring. However, some of the existing SDI methods cannot provide enough identification accuracy and efficiency in practice. A novel whale optimization algorithm (WOA) based method is proposed for SDI by weighting modal data and flexibility assurance criterion in this study. At first, the SDI problem is mathematically converted into a constrained optimization problem. Unlike traditional objective function defined using frequencies and mode shapes, a new objective function on the SDI problem is formulated by weighting both modal data and flexibility assurance criterion. Then, the WOA method, due to its good performance of fast convergence and global searching ability, is adopted to provide an accurate solution to the SDI problem, different predator mechanisms are formulated and their probability thresholds are selected. Finally, the performance of the proposed method is assessed by numerical simulations on a simply-supported beam and a 31-bar truss structures. For the given multiple structural damage conditions under environmental noises, the WOA-based SDI method can effectively locate structural damages and accurately estimate severities of damages. Compared with other optimization methods, such as particle swarm optimization and dragonfly algorithm, the proposed WOA-based method outperforms in accuracy and efficiency, which can provide a more effective and potential tool for the SDI problem.

Key Words
structural damage identification; whale optimization algorithm; constrained optimization problem; objective function; flexibility assurance criterion

Address
MOE Key Laboratory of Disaster Forecast and Control in Engineering, School of Mechanics and Construction Engineering, Jinan University, Guangzhou 510632, China

Abstract
Concurrent topology optimization of macrostructure and microstructure has attracted significant interest due to its high structural performance. However, most of the existing works are carried out under deterministic conditions, the obtained design may be vulnerable or even cause catastrophic failure when the load position exists uncertainty. Therefore, it is necessary to take load position uncertainty into consideration in structural design. This paper presents a computational method for robust concurrent topology optimization with consideration of load position uncertainty. The weighted sum of the mean and standard deviation of the structural compliance is defined as the objective function with constraints are imposed to both macro- and micro-scale structure volume fractions. The Bivariate Dimension Reduction method and Gauss-type quadrature (BDRGQ) are used to quantify and propagate load uncertainty to calculate the objective function. The effective properties of microstructure are evaluated by the numerical homogenization method. To release the computation burden, the decoupled sensitivity analysis method is proposed for microscale design variables. The bi-directional evolutionary structural optimization (BESO) method is used to obtain the black-and-white designs. Several 2D and 3D examples are presented to validate the effectiveness of the proposed robust concurrent topology optimization method.

Key Words
load position uncertainty; robust concurrent topology optimization; homogenization method; Bivariate Dimension Reduction method; Gauss-type quadrature

Address
Jinhu Cai: School of Mechanical Engineering and Automation, Beihang University, Beijing, China Chunjie Wang : State Key Laboratory of Virtual Reality and Systems, Beihang University, Beijing, China

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