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CONTENTS
Volume 34, Number 5, March10 2020
 

Abstract
The realistic modeling of the beam-column semi-rigid connection in steel frames attracted the attention of many researchers in the past for the seismic analysis of semi-rigid frames. Comparatively less studies have been made to investigate the behavior of steel frames with semi-rigid connections under different types of earthquake. Herein, the seismic behavior of semi-rigid steel frames is investigated under both far and near-field earthquakes. The semi-rigid connection is modeled by the multilinear plastic link element consisting of rotational springs. The kinematic hysteresis model is used to define the dynamic behavior of the rotational spring, describing the nonlinearity of the semi-rigid connection as defined in SAP2000. The nonlinear time history analysis (NTHA) is performed to obtain response time histories of the frame under scaled earthquakes at three PGA levels denoting the low, medium and high-level earthquakes. The other important parameters varied are the stiffness and strength parameters of the connections, defining the degree of semi-rigidity. For studying the behavior of the semi-rigid frame, a large number of seismic demand parameters are considered. The benchmark for comparison is taken as those of the corresponding rigid frame. Two different frames, namely, a five-story frame and a ten-story frame are considered as the numerical examples. It is shown that semi-rigid frames prove to be effective and beneficial in resisting the seismic forces for near-field earthquakes (PGA = 0.2g), especially in reducing the base shear to a considerable extent for the moderate level of earthquake. Further, the semi-rigid frame with a relatively weaker beam and less connection stiffness may withstand a moderately strong earthquake without having much damage in the beams.

Key Words
nonlinear time history analysis; semi-rigid steel frame; near-field; far-field earthquakes

Address
Vijay Sharma: Department of Civil Engineering, Malaviya National Institute of Technology Jaipur, JLN Marg, Jaipur 302017, India
Mahendra K. Shrimali, Shiv D. Bharti and Tushar K. Datta: National Centre for Disaster Mitigation and Management, Malaviya National Institute of Technology Jaipur,
JLN Marg Jaipur, 302017, India


Abstract
In the present work, the buckling behavior of a single-layered graphene sheet (SLGS) embedded in visco-Pasternak\' s medium is studied using nonlocal four-unknown integral model. This model has a displacement field with integral terms which includes the effect of transverse shear deformation without using shear correction factors. The visco-Pasternak\'s medium is introduced by considering the damping effect to the classical foundation model which modeled by the linear Winkler\'s coefficient and Pasternak\' s coefficients, damping parameter, and mode numbers on the buckling response of the SLGSs are studied and discussed.

Key Words
non-uniform buckling; four-unknown integral model; nonlocal elasticity theory; visco-Pasternak\'s medium

Address
Moussa Bellal and Houari Heireche: Laboratoire de Modélisation et Simulation Multi-échelle, Département de Physique, Faculté des Sciences Exactes,
Département de Physique, Université de Sidi Bel Abbés, Algeria
Habib Hebali: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
University Mustapha Stambouli of Mascara, Civil Engineering Department, Mascara, Algeria
Abdelmoumen Anis Bousahla and Abdeldjebbar Tounsi: 1Laboratoire de Modélisation et Simulation Multi-échelle, Département de Physique, Faculté des Sciences Exactes,
Département de Physique, Université de Sidi Bel Abbés, Algeria;
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran,
Eastern Province, Saudi Arabia
Fouad Bourada: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
Département des Sciences et de la Technologie, centre universitaire de Tissemsilt, BP 38004 Ben Hamouda, Algeria
S.R. Mahmoud: GRC Department, Jeddah Community College, King Abdulaziz University, Jeddah, Saudi Arabia
E.A. Adda Bedia: Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Abdelouahed Tounsi : Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran,
Eastern Province, Saudi Arabia






Abstract
In this paper, vibration analysis of functionally graded nanoshell is studied based on the sinusoidal higher-order shear and normal deformation theory to account thickness stretching effect. To account size-dependency, Eringen nonlocal elasticity theory is used. For more accurate modeling the problem and corresponding numerical results, sinusoidal higher-order shear and normal deformation theory including out of plane normal strain is employed in this paper. The radial displacement is decomposed into three terms to show variation along the thickness direction. Governing differential equations of motion are derived using Hamilton\'s principle. It is assumed that the cylindrical shell is made of an arbitrary composition of metal and ceramic in which the local material properties are measured based on power law distribution. To justify trueness and necessity of this work, a comprehensive comparison with some lower order and lower dimension works and also some 3D works is presented. After presentation of comparative study, full numerical results are presented in terms of significant parameters of the problem such as small scale parameter, length to radius ratio, thickness to radius ratio, and number of modes.

Key Words
thickness stretching effect; shear and normal deformation theory; free vibration analysis; length scale parameter; nonlocal theory

Address
Maryam Lori Dehsaraji, Mohammad Arefi and Abbas Loghman: Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, Iran

Abstract
The new energy-based criterion, named Reinforcement Strain Energy Density (ReiSED), is proposed to investigate the fracture behavior of the cracked orthotropic materials in which the crack is embedded in the matrix along the fibers. ReiSED is an extension of the well-known minimum strain energy density criterion. The concept of the reinforced isotropic solid as an advantageous model is the basis of the proposed mixed-mode I/II criterion. This model introduces fibers as reinforcements of the isotropic matrix in orthotropic materials. The effects of fibers are qualified by defining reinforcement coefficients at tension and shear modes. These coefficients, called Reduced Stress (ReSt), provide the possibility of encompassing the fiber fraction in a fracture criterion for the first time. Comparing ReiSED fracture limit curve with experimental data proves the high efficiency of this criterion to predict the fracture behavior of orthotropic materials.

Key Words
minimum strain energy density criterion; reinforcement coefficients; reinforced matrix; fracture limit curve

Address
Hannaneh Manafi Farid and Mahdi Fakoor: Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran

Abstract
The paper addresses contribution to the modeling and optimization of major machinability parameters (cutting force, surface roughness, and tool wear) in finish dry hard turning (FDHT) for machinability evaluation of hardened AISI grade die steel D3 with PVD-TiN coated (Al2O3–TiCN) mixed ceramic tool insert. The turning trials are performed based on Taguchi\'s L18 orthogonal array design of experiments for the development of regression model as well as adequate model prediction by considering tool approach angle, nose radius, cutting speed, feed rate, and depth of cut as major machining parameters. The models or correlations are developed by employing multiple regression analysis (MRA). In addition, statistical technique (response surface methodology) followed by computational approaches (genetic algorithm and particle swarm optimization) have been employed for multiple response optimization. Thereafter, the effectiveness of proposed three (RSM, GA, PSO) optimization techniques are evaluated by confirmation test and subsequently the best optimization results have been used for estimation of energy consumption which includes savings of carbon footprint towards green machining and for tool life estimation followed by cost analysis to justify the economic feasibility of PVD-TiN coated Al2O3+TiCN mixed ceramic tool in FDHT operation. Finally, estimation of energy savings, economic analysis, and sustainability assessment are performed by employing carbon footprint analysis, Gilbert approach, and Pugh matrix, respectively. Novelty aspects, the present work: (i) contributes to practical industrial application of finish hard turning for the shaft and die makers to select the optimum cutting conditions in a range of hardness of 45-60 HRC, (ii) demonstrates the replacement of expensive, time-consuming conventional cylindrical grinding process and proposes the alternative of costlier CBN tool by utilizing ceramic tool in hard turning processes considering technological, economical and ecological aspects, which are helpful and efficient from industrial point of view, (iii) provides environment friendliness, cleaner production for machining of hardened steels, (iv) helps to improve the desirable machinability characteristics, and (v) serves as a knowledge for the development of a common language for sustainable manufacturing in both research field and industrial practice.

Key Words
machinability; hard turning; AISI D3 steel; optimization; economical analysis; sustainability assessment

Address
Asutosh Panda, Sudhansu Ranjan Dasand Debabrata Dhupal: Department of Production Engineering, Veer Surendra Sai University of Technology, Burla 768018, India

Abstract
The aerodynamic performance of long-span cable-stayed bridges is much dependent on its geometrical configuration and countermeasure strategies. In present study, the aerodynamic performance of three composite cable-stayed bridges with different tower configurations and passive aerodynamic countermeasure strategies is systematically investigated by conducting a series of wind tunnel tests in conjunction with theoretical analysis. The structural characteristics of three composite bridges were firstly introduced, and then their stationary aerodynamic performance and wind-vibration performance (i.e., flutter performance, VIV performance and buffeting responses) were analyzed, respectively. The results show that the bridge with three symmetric towers (i.e., Bridge I) has the lowest natural frequencies among the three bridges, while the bridge with two symmetric towers (i.e., Bridge II) has the highest natural frequencies. Furthermore, the Bridge II has better stationary aerodynamic performance compared to two other bridges due to its relatively large drag force and lift moment coefficients, and the improvement in stationary aerodynamic performance resulting from the application of different countermeasures is limited. In contrast, it demonstrates that the application of both downward vertical central stabilizers (UDVCS) and horizontal guide plates (HGP) could potentially significantly improve the flutter and vortex-induced vibration (VIV) performance of the bridge with two asymmetric towers (i.e., Bridge III), while the combination of vertical interquartile stabilizers (VIS) and airflow-depressing boards (ADB) has the capacity of improving the VIV performance of Bridge II.

Key Words
cable-stayed bridge; composite deck; tower system; wind tunnel tests; aerodynamic performance; passive aerodynamic countermeasures

Address
Rui Zhou and Yanliang Du: Institute of Urban Smart Transportation & Safety Maintenance, Shenzhen University, Shenzhen, 518060, China
Yaojun Ge and Yongxin Yang: State Key Lab for Disaster Reduction in Civil Engineering, Tongji University, Shanghai 200092, China
Lihai Zhang: Department of Infrastructure Engineering, University of Melbourne, VIC 3010, Australia

Abstract
High-strength steel composite Y-eccentrically braced frame (Y-HSS-EBF) is a novel structural system. In this study, the spatial substructure hybrid simulation test (SHST) method is used to further study the seismic performance of Y-HSS-EBF. Firstly, based on the cyclic loading tests of two single-story single-span Y-HSS-EBF planar specimens, a finite element model in OpenSees was verified to provide a reference for the numerical substructure analysis model for the later SHST. Then, the SHST was carried out on the OpenFresco test platform. A three-story spatial Y-HSS-EBF model was taken as the prototype, the top story was taken as the experimental substructure, and the remaining two stories were taken as the numerical substructure to be simulated in OpenSees. According to the test results, the validity of the SHST was verified, and the main seismic performance indexes of the SHST model were analyzed. The results show that, the SHST based on the OpenFresco platform has good stability and accuracy, and the results of the SHST agree well with the global numerical model of the structure. Under strong seismic action, the plastic deformation of Y-HSS-EBF mainly occurs in the shear link, and the beam, beam-columns and braces can basically remain in the elastic state, which is conducive to post-earthquake repair.

Key Words
high strength steel; Y-eccentrically braced frame; link; spatial substructure; hybrid simulation

Address
Tengfei Li: School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an 710055, P.R. China
Mingzhou Su and Yan Sui: Key Lab of Structural Engineering and Earthquake Resistance, Ministry of Education (XAUAT), Xi\'an 710055, P.R. China

Abstract
Vibration analysis in nanocomposite plate with smart layer is studied in this article. The plate is reinforced by carbon nanotubes where the Mori-Tanaka law is utilized for obtaining the effective characteristic of structure assuming agglomeration effects. The nanocomposite plate is located in elastic medium which is simulated by spring element. The motion equations are derived based on first order shear deformation theory and Hamilton\' s s principle. Utilizing Navier method, the frequency of the structure is calculated and the effects of applied voltage, volume percent and agglomeration of Carbon nanotubes, elastic medium and geometrical parameters of structure are shown on the frequency of system. Results indicate that with applying negative voltage, the frequency of structure is increased. In addition, the agglomeration of carbon nanotubes reduces the frequency of the nanocomposite plate.

Key Words
nanocomposite plate; vibration; smart layer; elastic medium; exact method

Address
Ahmad Farrokhian: Mechanical Engineering group, Pardis College, Isfahan University of Technology, Isfahan 84156-83111, Iran

Abstract
Due to the impressive flexural performance, enhanced compressive strength and more constrained crack propagation, Fibre-reinforced concrete (FRC) have been widely employed in the construction application. Majority of experimental studies have focused on the seismic behavior of FRC columns. Based on the valid experimental data obtained from the previous studies, the current study has evaluated the seismic response and compressive strength of FRC rectangular columns while following hybrid metaheuristic techniques. Due to the non-linearity of seismic data, Adaptive neuro-fuzzy inference system (ANFIS) has been incorporated with metaheuristic algorithms. 317 different datasets from FRC column tests has been applied as one database in order to determine the most influential factor on the ultimate strengths of FRC rectangular columns subjected to the simulated seismic loading. ANFIS has been used with the incorporation of Particle Swarm Optimization (PSO) and Genetic algorithm (GA). For the analysis of the attained results, Extreme learning machine (ELM) as an authentic prediction method has been concurrently used. The variable selection procedure is to choose the most dominant parameters affecting the ultimate strengths of FRC rectangular columns subjected to simulated seismic loading. Accordingly, the results have shown that ANFIS-PSO has successfully predicted the seismic lateral load with R2 = 0.857 and 0.902 for the test and train phase, respectively, nominated as the lateral load prediction estimator. On the other hand, in case of compressive strength prediction, ELM is to predict the compressive strength with R2 = 0.657 and 0.862 for test and train phase, respectively. The results have shown that the seismic lateral force trend is more predictable than the compressive strength of FRC rectangular columns, in which the best results belong to the lateral force prediction. Compressive strength prediction has illustrated a significant deviation above 40 Mpa which could be related to the considerable non-linearity and possible empirical shortcomings. Finally, employing ANFIS-GA and ANFIS-PSO techniques to evaluate the seismic response of FRC are a promising reliable approach to be replaced for high cost and time-consuming experimental tests.

Key Words
ANFIS; PSO; GA; ELM; fibre-reinforced concrete; Seismic response; compressive strength

Address
Chanjuan Liu: School of Computer Science and Technology, Dalian University of Technology, Dalian 116024, China
Xinling Wu: South China Business College, Guang Dong University of Foreign Studies, Guangzhou 510545, China
Karzan Wakil: Research Center, Sulaimani Polytechnic University, Sulaimani 46001, Kurdistan Region, Iraq;
Research Center, Halabja University, Halabja 46018, Kurdistan Region, Iraq
Kittisak Jermsittiparsert: Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam;
Faculty of Social Sciences and Humanities, Ton Duc Thang University, Ho Chi Minh City, Vietnam
Lanh Si Ho: Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam.
Hisham Alabduljabbar,Rayed Alyousef and Abdeliazim Mustafa Mohamed: Department of Civil Engineering, College of Engineering, Prince Sattam bin Abdulaziz University, Al-kharj 11942, Saudi Arabia
Abdulaziz Alaskar and Fahed Alrshoudi: Department of Civil Engineering, College of Engineering, King Saud University, Riyadh 11362, Saudi Arabia




Abstract
A Prestressed stayed steel column is an efficient and lightweight way with regard to enhancing the stability behaviour of a compression column. In the past, researchers primarily concentrated on investigating the behaviour of stayed steel columns with horizontal crossarms. However, this article focuses on prestressed stayed steel columns with split-up crossarm system, in which the crossarms are aslant and rotational symmetrically arranged. A mathematical formula calculating the optimal pretension that corresponds to the maximum critical buckling load was established according to geometric analysis based on the small deformation assumption. It was demonstrated that critical buckling mode of this stayed column is different from the one with horizontal crossarms. The governing imperfection direction that should be adopted in the nonlinear buckling analysis was determined in this work. In addition, the effects of crossarm inclination, stay diameter, and crossarm length on the stability behaviour were investigated. An influencing factor denotes the ratio of the load carrying capacity of the prestressed stayed steel column to the Euler load of the main column was also obtained.

Key Words
stayed column; split-up crossarm; numerical analysis; buckling load; geometric analysis

Address
Pengcheng Li and Zhiqiang Li: School of Civil Engineering, Chongqing University, Chongqing 400045, China
Bin Jia: Sichuan Institute of Building Research, Chengdu 610081, China
Hao Wang: School of Civil Engineering, Shandong Jianzhu University, Jinan 250101, China

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