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CONTENTS
Volume 44, Number 2, July25 2022
 

Abstract
In the present paper an analytical model was developed to study the non‐linear vibrations of Functionally Graded Carbon Nanotube (FG-CNT) reinforced doubly-curved shallow shells using the Multiple Scales Method (MSM). The nonlinear partial differential equations of motion are based on the FGM shallow shell hypothesis, the non‐linear geometric Von-Karman relationships, and the Galerkin method to reduce the partial differential equations associated with simply supported boundary conditions. The novelty of the present model is the simultaneous prediction of the natural frequencies and their mode shapes versus different curvatures (cylindrical, spherical, conical, and plate) and the different types of FG-CNTs. In addition to combining the vibration analysis with optimization algorithms based on the genetic algorithm, a design optimization methode was developed to maximize the natural frequencies. By considering the expression of the non-dimensional frequency as an objective optimization function, a genetic algorithm program was developed by valuing the mechanical properties, the geometric properties and the FG-CNT configuration of shallow double curvature shells. The results obtained show that the curvature, the volume fraction and the types of NTC distribution have considerable effects on the variation of the Dimensionless Fundamental Linear Frequency (DFLF). The frequency response of the shallow shells of the FG-CNTRC showed two types of nonlinear hardening and softening which are strongly influenced by the change in the fundamental vibration mode. In GA optimization, the mechanical properties and geometric properties in the transverse direction, the volume fraction, and types of distribution of CNTs have a considerable effect on the fundamental frequencies of shallow double-curvature shells. Where the difference between optimized and not optimized DFLF can reach 13.26%.

Key Words
FG-CNTs; natural frequencies; non‐linear vibration; optimization; shallow shell

Address
Zakia Hammou: Physical chemistry Department, Chemistry Faculty, University of Science and Technology of Oran, USTO, Oran, Algeria

Zakia Guezzen: Composite Structures and Innovative Materials Laboratory, Mechanical Engineering Faculty, University of Science and Technology of Oran, BP 1505 El M'naouer, USTO, Oran, Algeria

Fatima Z. Zradni: Oorganic Synthesis, Physico-chemistry, Biomolecular and Environment Laboratory, Chemical Engineering Department, Chemistry Faculty, University of Science and Technology of Oran, USTO, Oran, Algeria

Zouaoui Sereir: Composite Structures and Innovative Materials Laboratory, Mechanical Engineering Faculty, University of Science and Technology of Oran, BP 1505 El M'naouer, USTO, Oran, Algeria

Abdelouahed Tounsi: YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea 5Material and Hydrology Laboratory, University of SidiBel Abbes, Faculty of Technology, Civil Engineering Department, Algeria

Yamna Hammou: Maritime Sciences and Engineering Laboratory, Mechanical Engineering Faculty, University of Science and Technology of Oran, BP 1505 El M'naouer, USTO, Oran, Algeria


Abstract
Functionally graded material (FGM) has been spotlighted as an advanced composite material due to its excellent thermo-mechanical performance. And the buckling of FGM resting on elastic foundations has been a challenging subject because its behavior is directly connected to the structural safety. In this context, this paper is concerned with a numerical buckling analysis of metal-ceramic FG plates resting on a two-parameter (Pasternak-type) elastic foundation. The buckling problem is formulated based on the neutral surface and the (1,1,0) hierarchical model, and it is numerically approximated by 2-D natural element method (NEM) which provides a high accuracy even for coarse grid. The derived eigenvalue equations are solved by employing Lanczos and Jacobi algorithms. The numerical results are compared with the reference solutions through the benchmark test, from which the reliability of present numerical method has been verified. Using the developed numerical method, the critical buckling loads of metal-ceramic FG plates are parametrically investigated with respect to the major design parameters.

Key Words
metal-ceramic FG plate; pasternak-type elastic foundation; neutral surface; buckling analysis; critical buckling load; natural element method (NEM); hierarchical model

Address
J.R. Cho:Department of Naval Architecture and Ocean Engineering, Hongik University, Sejong 30016, Korea

Abstract
Plastic deformation of link beams in eccentrically braced frames is the primary dissipating source of seismic energy. Despite the excellent compatibility with the architectural designs, previous researches indicate the deficiency of flexural yielding links compared to the shear yielding ones because of their localized plastic deformation. Previous investigations have shown that implementing web openings in beams could be an efficient method to improve the seismic performance of moment-resisting connections. Accordingly, this research investigates the use of flexural links with stiffened and un-stiffened web openings to eliminate localized plasticity at the ends of the link. For this purpose, the numerical models are generated in finite element software "Abaqus" and verified against experimental data gathered from other studies. Models are subjected to cyclic displacement history to evaluate their behavior. Failure of the numerical models under cyclic loading is simulated using a micromechanical based damage model known as Cyclic Void Growth Model (CVGM). The elastic stiffness and the strength-based and CVGM-based inelastic rotation capacity of the links are compared to evaluate the studied models' seismic response. The results of this investigation indicate that some of the flexural links with edge stiffened web openings show increased inelastic rotation capacity compared to an un-perforated link.

Key Words
cyclic loading; Eccentrically Braced Frames (EBF); Finite element modeling (FEM); Reduced web section (RWS

Address
S. Erfani, A. Vakili:Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran

V. Akrami:Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran

Abstract
This study build finite element analysis (FEA) models describing the bending events of coiled tubing (CT) at the wellhead and trips into the hole, accurately provide the state of stress and strain while the CT is in service. The bending moment and axial force history curves are used as load and boundary conditions in the diametrical growth models to ensure consistency with the actual working conditions in field operations. The simulation diametrical growth results in this study are more accurate and reasonable. Analysis the factors influencing fatigue and diametrical growth shows that the internal pressure has a first-order influence on fatigue, followed by the radius of the guide arch, reel and the CT diameter. As the number of trip cycles increase, fatigue damage, residual stress and strain cumulatively increase, until CT failure occurs. Significant residual stresses remain in the CT cross-section, and the CT exhibits a residual curvature, the initial residual bending configuration of CT under wellbore constraints, after running into the hole, is sinusoidal. The residual stresses and residual bending configuration significantly decrease the buckling load, making the buckling and buckling release of CT in the downhole an elastic-plastic process, exacerbating the helical lockup. The conclusions drawn in this study will improve CT models and contribute to the operational and economic success of CT services.

Key Words
bending and straightening cycles; buckling; coiled tubing; diametrical growth; residual curvature configuration

Address
Le Zhao:Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth
Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China

Mingzhong Gao:1)Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth
Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China
2)Key Laboratory of Deep Earth Science and Engineering (Sichuan University), Ministry of Education, Chengdu, 10065, China

Cunbao Li:Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth
Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China

Linyun Xian:1)Shanxi Province Key Laboratory of High Performance Coiled Tubing, Baoji 721008, Shaanxi, China
2)Chinese National Engineering Research Center for Petroleum and Natural Gas Tubular Goods, Baoji 721008, China

Abstract
Multi-objective optimization was conducted to obtain the optimal configuration of a composite sandwich structure with honeycomb-foam hybrid core subjected to underwater shock waves, which can fulfill the demand for light weight and energy efficient design of structures against underwater blast. Effects of structural parameters on the dynamic response of the sandwich structures subjected to underwater shock waves were analyzed numerically, from which the correlations of different parameters to the dynamic response were determined. Multi-objective optimization of the structure subjected to underwater shock waves of which the initial pressure is 30 MPa was conducted based on surrogate modelling method and genetic algorithm. Moreover, optimization results of the sandwich structure subjected to underwater shock waves with different initial pressures were compared. The research can guide the optimal design of composite sandwich structures subjected to underwater shock waves.

Key Words
composite sandwich structures; multi-objective optimization; numerical simulation; surrogate model; underwater shock waves

Address
Hao Zhou:1)National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, 200 Xiaolingwei Street,
Nanjing 210094, P. R. China
2)School of Mechanical Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, P. R. China

Rui Guo:School of Mechanical Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, P. R. China

Wei Jiang:National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, 200 Xiaolingwei Street,
Nanjing 210094, P. R. China

Rongzhong Liu:School of Mechanical Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, P. R. China

Pu Song:Xi'an Modern Chemistry Research Institute, 168 Zhangbadong Road, Xi

Abstract
Local responses of steel plate-concrete composite (SC) walls under impact loads are typically evaluated using design equations available in the AISC N690s1-15. These equations enable design of impact-resistant SC walls, but some essential parts such as the effects of wall size and shear reinforcement ratio have not been addressed. Also, since they were developed for design basis events, improved equations are required for accurate prediction of the impact behaviors of SC walls for beyond design basis impact evaluation. This paper presents a numerical study to construct a robust numerical model of SC walls subjected to impact loads to reasonably predict the SC-wall impact behavior, to evaluate the findings observed from the impact tests including the effects of the key design parameters, and to assess the actual responses of full-scale SC walls. The numerical calculations are validated using intermediate-scale impact tests performed previously. The influences of the fracture energy of concrete and the conservative aspects of the current design equations are discussed carefully. Recommendations are made for design practice.

Key Words
conservatism; design equation; impact load; numerical analysis; SC wal

Address
Kyungkoo Lee:Department of Architectural Engineering, Dankook University, 152 Jukjeon-ro, Suji-gu, Yongin-si 16890, Republic of Korea

Jinwon Shin:Department of Architectural Engineering, Catholic Kwandong University, 24, Beomil-ro 579 beon-gil Gangneung-si 25601, Republic of Korea

Jungwhee Lee:Department of Civil and Environmental Engineering, Dankook University, 152 Jukjeon-ro, Suji-gu, Yongin-si 16890, Republic of Korea

Kapsun Kim:Central Research Institute, Korea Hydro & Nuclear Power Co., LTD,
70, 1312 Beon-gil, Yuseong-daero, Yuseong-gu, Daejeon 305-343, Republic of Korea

Abstract
The cables in a cable-stayed bridge are critical load-carrying parts. The potential damage to cables should be identified early to prevent disasters. In this study, an efficient deep learning model is proposed for the damage identification of cables using both a multi-layer perceptron (MLP) and a graph neural network (GNN). Datasets are first generated using the practical advanced analysis program (PAAP), which is a robust program for modeling and analyzing bridge structures with low computational costs. The model based on the MLP and GNN can capture complex nonlinear correlations between the vibration characteristics in the input data and the cable system damage in the output data. Multiple hidden layers with an activation function are used in the MLP to expand the original input vector of the limited measurement data to obtain a complete output data vector that preserves sufficient information for constructing the graph in the GNN. Using the gated recurrent unit and set2set model, the GNN maps the formed graph feature to the output cable damage through several updating times and provides the damage results to both the classification and regression outputs. The model is fine-tuned with the original input data using Adam optimization for the final objective function. A case study of an actual cable-stayed bridge was considered to evaluate the model performance. The results demonstrate that the proposed model provides high accuracy (over 90%) in classification and satisfactory correlation coefficients (over 0.98) in regression and is a robust approach to obtain effective identification results with a limited quantity of input data.

Key Words
cable-stayed bridge; cable damage identification; deep learning; graph neural network; multi-layer perceptron; vibration characteristics

Address
Van-Thanh Pham:Department. of Civil and Environmental Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 05006, South Korea

Yun Jang:Department. of Computer Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 05006, South Korea

Jong-Woong Park:School of Civil and Environmental Engineering, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 06974, South Korea

Dong-Joo Kim:Department. of Civil and Environmental Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 05006, South Korea

Seung-Eock Kim:Department. of Civil and Environmental Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 05006, South Korea


Abstract
This manuscript illustrates the dynamic response of nanoscale carbon nanotubes (CNTs) embedded in an elastic media under moving load using doublet mechanics theory, which not considered before. CNTs are modelled by Timoshenko beam theory (TBT) and a bottom to up modelling nano-mechanics is simulated by doublet mechanics theory to capture the size effect of CNTs. To explore the influence of the CNTs configurations on the dynamic behaviour, both armchair and zigzag configurations are considered. The governing equations of motion and the associated boundary conditions are obtained using the Hamiltonian principle. The Navier solution methodology is applied to obtain the solutions for both orientations. Free vibration and forced response under moving loads are considered. The accuracy of the developed procedure is verified by comparing the obtained results with available previous algorithms and good agreement is observed. Parametric studies are conducted to demonstrate effects of doublet length scale, CNTs configurations, moving load velocities as well as the elastic media parameters on the dynamic behaviours of CNTs. The developed procedure is supportive in the design and manufacturing of MEMS/NEMS made from CNTs.

Key Words
armchair and zigzag CNTs; doublet mechanics theory; dynamic behaviour; elastic media; moving loads; navier method

Address
A. Abdelrahman:Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Rabab A. Shanab:Engineering Mathematics Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt

Ismail Esen:Department of Mechanical Engineering, Karabuk University, Karabuk, Turkey

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

Abstract
This study discusses challenges of running expandable profile liners (EPLs) to isolate trouble zones in directional section of a deep well, and summary the expandable profile liner technology (EPLT) field trial experience. Technically, the trial result reveals that it is feasible to apply the EPLT solving lost-circulation control problem and wellbore instability in the deep directional section. Propose schemes for optimizing the EPLT operation procedure to break through the existing bottleneck of EPLT in the deep directional section. Better-performing transition joints are developed to improve EPL string reliability in high borehole curvature section. High-performing and reliable expanders reduce the number of trips, offer excellent mechanical shaping efficiency, simplify the EPLT operation procedure. Application of the expansion and repair integrated tool could minimize the risk of insufficient expansion and increase the operational length of the EPL string. The new welding process and integrated automatic welding equipment improve the welding quality and EPL string structural integrity. These optimization schemes and recent new advancements in EPLT can bring significant economic benefits and promote the application of EPLT to meet future challenges.

Key Words
expandable profile liner technology; isolating drilling trouble zones; mechanical shaping tools; optimizable schemes; welding process and equipment

Address
Le Zhao:Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth
Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China

Yulin Tu:SINOPEC Tech Middle East LLC, Dhahran, Saudi Arabia

Heping Xie:Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth
Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China

Mingzhong Gao:Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization, Institute of Deep Earth
Sciences and Green Energy, College of Civil and Transportation Engineering, Shenzhen University, Shenzhen, 518060, China

Fei Liu:College of Emergency Management, Nanjing Tech University, Nanjing, 211816, China

Abstract
In this study, a new seismic retrofit scheme of building structures is developed by combining a steel moment frame and steel slit plates to be installed inside of an existing reinforced concrete frame. This device has the energy dissipation capability of slit dampers with slight loss of stiffness compared to the conventional steel frame reinforcement method. In order to investigate the seismic performance of the retrofit system, it was installed inside of a reinforced concrete frame and tested under cyclic loading. Finite element analysis was carried out for validation of the test results, and it was observed that the analysis and the test results match well. An analytical model was developed to apply the retrofit system to a commercial software to be used for seismic retrofit design of an example structure. The effectiveness of the retrofit scheme was investigated through nonlinear time-history response analysis (NLTHA). The cyclic loading test showed that the steel frame with slit dampers provides significant increase in strength and ductility to the bare structure. According to the analysis results of a case study building, the proposed system turned out to be effective in decreasing the seismic response of the model structure below the given target limit state.

Key Words
cyclic test; non-linear dynamic analysis; seismic retrofit; slit damper; steel frame

Address
Hyungoo Kang:Decomissioning Waste R&D Team, Korea Radioactive Waste Agency (KORAD), 168, Gajeong-ro, Yuseong-gu, Daejeon, Korea 34129

Michael Adane, Seungho Chun and Jinkoo Kim:Department of Global Smart City, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, Korea


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