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Volume 28, Number 5, September10 2018
 
select * from journal_scs where volume=28 and num=5 order by ordernum asc

Abstract
The specimens made by Z2CND18.12N austenitic stainless steel were conducted on a 100 kN closed loop servo hydraulic tension-compression testing machine with a digital controller. Uniaxial tension and uniaxial ratcheting effect tests were carried out at 25

Key Words
BP neural network; constitutive relationship; Z2CND18.12N austenitic stainless steel; ratcheting strain; temperature

Address
(1) Xingang Wang, Xiaohui Chen, Mingming Yan, Miaoxin Chang:
Mechanical Engineering and Automation, Center of Mechanical Reliability & Dynamics, Northeastern University, Taishan Road, Development District, Qinhuangdao, Hebei Province, 066004, China;
(2) Xiaohui Chen:
School of Chemical Engineering and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin, China, 300072, China.

Abstract
The use of reinforced concrete (RC) shear wall with concrete filled steel tube (CFST) columns and steel fiber reinforced concrete (SFRC) shear wall has aroused widespread attention in recent years. A new shear wall, named SFRC shear wall with CFST columns, is proposed in this paper, which makes use of CFST column and SFRC shear wall. Six SFRC shear wall with CFST columns specimens were tested under cyclic loading. The effects of test parameters including steel fiber volume fraction and concrete strength on the failure mode, strength, ductility, rigidity and dissipated energy of shear wall specimens were investigated. The results showed that all tested shear wall specimens exhibited a distinct shear failure mode. Steel fibers could effectively control the crack width and improve the distribution of cracks. The load carrying and energy dissipation capacities of specimens increased with the increase of steel fiber volume fraction and concrete strength, whilst the ductility of specimens increased with the increase of steel fiber volume fraction and the decrease of concrete strength.

Key Words
concrete filled steel tube columns; shear wall; steel fiber reinforced concrete; seismic behavior; ductility; dissipated energy

Address
(1) Dan-Ying Gao, Pei-Bo You, Li-Juan Zhang, Huan-Huan Yan:
Research Center of New Style Building Material & Structure, Zhengzhou University, Zhengzhou 450001, China;
(2) Dan-Ying Gao:
College of Civil Engineering, Henan University of Engineering, Zhengzhou 451191, China;
(3) Pei-Bo You:
Henan University of Urban Construction, Pingdingshan 467000, China.

Abstract
This paper presents the influence of carbon nanotubes (CNTs) waviness and aspect ratio on the vibrational behavior of functionally graded nanocomposite sandwich annular sector plates resting on two-parameter elastic foundations. The carbon nanotube-reinforced (CNTR) sandwich plate has smooth variation of CNT fraction along the thickness direction. The distributions of CNTs are considered functionally graded (FG) or uniform along the thickness and their mechanical properties are estimated by an extended rule of mixture. In this study, the classical theory concerning the mechanical efficiency of a matrix embedding finite length fibers has been modified by introducing the tube-to-tube random contact, which explicitly accounts for the progressive reduction of the tubes' effective aspect ratio as the filler content increases. Effects of CNT distribution, volume fraction, aspect ratio and waviness, and also effects of Pasternak's elastic foundation coefficients, sandwich plate thickness, face sheets thickness and plate aspect ratio are investigated on the free vibration of the sandwich plates with wavy CNT-reinforced face sheets. The study is carried out based on three-dimensional theory of elasticity and in contrary to two-dimensional theories, such as classical, the first- and the higher-order shear deformation plate theories, this approach does not neglect transverse normal deformations. The sandwich annular sector plate is assumed to be simply supported in the radial edges while any arbitrary boundary conditions are applied to the other two circular edges including simply supported, clamped and free.

Key Words
CNTs waviness and aspect ratio; sandwich structures; vibration; rule of mixture; two-parameter elastic foundations; functionally graded materials; sectorial plates

Address
Young Researchers and Elite Club, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran.


Abstract
In current engineering practice, circular concrete-filled steel tubular (CFST) columns have been used as effective structural components due to their significant structural and economic benefits. To apply these structural components into steelconcrete composite moment resisting frames, increasing number of research into the column-base connections of circular CFST columns have been found. However, most of the previous research focused on the strength, rigidity and seismic resisting performance of the circular CFST column-base connections. The present paper attempts to investigate the demountability of bolted circular CFST column-base connections using the finite element method. The developed finite element models take into account the effects of material and geometric nonlinearities; the accuracy of proposed models is validated through comparison against independent experimental results. The mechanical performance of CFST column-base connections with both permanent and demountable design details are compared with the developed finite element models. Parametric studies are further carried out to examine the effects of design parameters on the behaviour of demountable circular CFST column-base connections. Moreover, the initial stiffness and moment capacity of such demountable connections are compared with the existing codes of practice. The comparison results indicate that an improved prediction method of the initial stiffness for these connections should be developed.

Key Words
circular concrete-filled steel tubular column; column-base connection; demountable; finite element analysis; design codes

Address
(1) Dongxu Li, Brian Uy:
School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia;
(2) Jia Wang:
School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia;
(3) Farhad Aslani:
School of Civil, Environmental and Mining Engineering, The University of Western Australia, Crawley, WA 6009, Australia;
(4) Vipul Patel:
School of Engineering and Mathematical Sciences, La Trobe University, Bendigo, VIC 3552, Australia.

Abstract
The objective of this paper is to investigate the mechanical performances of polygonal concrete-filled circular steel tubular (CFT) stub columns under axial loading through combined experimental and numerical study. A total of 32 specimens were designed to investigate the effect of the concrete strength and steel ratio on the compressive behavior of polygonal CFT stub columns. The ultimate bearing capacity, ductility and confinement effect were analyzed based on the experimental results and the failure modes were discussed in detail. Besides, ABAQUS was adopted to establish the three dimensional FE model. The composite action between the core concrete and steel tube was further discussed and clarified. It was found that the behavior of CFT stub column changes with the change of the cross-section, and the change is continuous. Finally, based on both experimental and numerical results, a unified formula was developed to estimate the ultimate bearing capacity of polygonal CFT stub columns according to the superposition principle with rational simplification. The predicted results showed satisfactory agreement with both experimental and FE results.

Key Words
polygonal concrete-filled steel tubular (CFT) stub column; ultimate bearing capacity; strain ratio; composite action; compressive behavior

Address
(1) Tao Zhang, Fa-xing Ding, Liping Wang, Guo-shuai Jiang:
School of Civil Engineering, Central South University, Changsha 410075, P.R. China;
(2) Tao Zhang, Liping Wang:
Engineering Technology Research Center for Prefabricated Construction Industrialization of Hunan Province, 410075, P.R. China;
(3) Xue-mei Liu:
School of Civil Engineering and Built Environment, Queensland University of Technology, Brisbane, QLD 4000, Australia.

Abstract
The previous studies reflected the significant effect of neutral-axis position and coupling of in-plane and out-of-plane displacements on behavior of functionally graded (FG) nanobeams. In thin FG beam, this coupling can be eliminated by a proper choice of the reference axis. In shear deformable FG nanobeam, not only this coupling can't be eliminated but also the position of neutral-axis is dependent on through-thickness distribution of shear strain. For the first time, in this paper it is avoided to guess a shear strain shape function and the exact shape function and consequently the exact position of neutral axis for arbitrary gradation of higher order nanobeam are obtained. This paper presents new methodology based on differential transform and collocation methods to solve coupled partial differential equations of motion without any simplifications. Using exact position of neutral axis and higher order beam kinematics as well as satisfying equilibrium equations and traction-free conditions without shear correction factor requirement yields to better results in comparison to the previously published results in literature. The classical rule of mixture and Mori-Tanaka homogenization scheme are considered. The Eringen.s nonlocal continuum theory is applied to capture the small scale effects. For the first time, the dependency of exact position of neutral axis on length to thickness ratio is investigated. The effects of small scale, length to thickness ratio, Poisson's ratio, inhomogeneity of materials and various end conditions on vibration and buckling of local and nonlocal FG beams are investigated. Moreover, the effect of axial load on natural frequencies of the first modes is examined. After degeneration of the governing equations, the exact new formulas for homogeneous nanobeams are computed.

Key Words
free vibration; buckling; arbitrary functionally graded beam; nonlocal elasticity theory; exact shear strain shape function

Address
Young Researchers and Elite Club, Ardabil Branch, Islamic Azad University, Ardabil, Iran.


Abstract
The dynamic behavior of the deployment and folding process of a foldable boom based on the Miura origami pattern is investigated in this paper. Firstly, mechanical behavior of a single storey during the motion is studied numerically. Then the deployment and folding of a multi-storey boom is discussed. Moreover, the influence of the geometry parameters and the number of Miura-ori elements n on the dynamic behavior of the boom is also studied. Finally, the influence of the imperfection on the dynamic behavior is investigated. The results show that the angles between the diagonal folds and horizontal folds will have great effect on the strains during the motion. A bistable configuration can be obtained by choosing proper fold angles for a given multi-storey boom. The influence of the imperfection on the folding behavior of the foldable mast is significant.

Key Words
origami; tubular structure; Miura-ori; boom; dynamic behavior; bistable

Address
(1) Jianguo Cai, Ya Zhou, Xinyu Wang, Jian Feng:
Key Laboratory of C & PC Structures of Ministry of Education, National Prestress Engineering Research Center, Southeast University, Nanjing 210096, China;
(2) Yixiang Xu:
Department of Mechanical Engineering, The University of Sheffield, Sheffield S10 2TN, United Kingdom.

Abstract
Steel shear wall possesses priority over many of the current lateral load-bearing systems due to reasons like higher elastic stiffness, desirable ductility and energy absorption, convenience in construction and implementation technology, and economic criteria. Besides these advantages, this system causes increase in the dimensions of other structural elements due to its high stiffness as one of its intrinsic characteristics. One of the methods for stiffness reduction is perforating the wall panel and creating openings in the wall that can also be used as windows or ducts in buildings service period. The aim of the present study is probing the appropriate geometric shape and location of opening to fulfil economic criterion plus technical and seismic design criteria. In the present research, a number of possible while reasonable opening shapes and locations are defined in various sizes for some steel shear wall specimens. The specimens are modelled in ABAQUS finite elements software and analyzed using nonlinear pushover analysis. Finally, the analyses' results are reported as force-displacement diagrams and the strength, the initial stiffness and the energy absorption are calculated for all specimens and compared together. The obtained results show that both shape and location of the openings affect the seismic parameters of the shear wall. The specimens in which the openings are further from the center and closer to the columns possess higher stiffness and strength while the specimens in which the openings are closer to the center show more considerable changes in their seismic parameters in response to increase in opening area.

Key Words
steel shear wall; openings' geometric shape; openings' location; seismic performance; nonlinear pushover analysis

Address
Department of Civil Engineering, Faculty of Engineering, Kharazmi University, Tehran, 15719-14911, Iran.


Abstract
In this paper, the vibroacoustic responses of baffled laminated composite sandwich flat panel structure under the influence of harmonic excitation are studied numerically using a novel higher-order coupled finite-boundary element model. A numerical scheme for the vibrating plate has been developed in the frame work of the higher-order mid-plane kinematics and the eigen frequencies are obtained by employing suitable finite element steps. The acoustic responses are then computed by solving the Helmholtz wave equation using boundary element method coupled with the structural finite elements. The proposed scheme has been implemented via an own MATLAB base code to compute the desired responses. The validity of the present model is established from the conformance of the current natural frequencies and the radiated sound power with the available benchmark solutions. The model is further utilized to scrutinize the influence of core-to-face thickness ratio, modular ratio, lamination scheme and the support condition on the sound radiation characteristics of the vibrating sandwich flats panel. It can be concluded that the present scheme is not only accurate but also efficient and simple in providing solutions of the coupled vibroacoustic response of laminated composite sandwich plates.

Key Words
laminated composite sandwich plate; vibroacoustic response; HSDT; FEM-BEM scheme; MATLAB computer code

Address
(1) Nitin Sharma:
School of Mechanical Engineering, KIIT, Bhubaneswar: 751024, Odisha, India;
(2) Trupti R. Mahapatra:
Department of Production Engineering, VSSUT, Burla: 768018, Odisha, India;
(3) Subrata K. Panda, Kulmani Mehar:
Department of Mechanical Engineering, NIT Rourkela: 769008, Odisha, India.

Abstract
This paper presents experiment and bearing capacity analyses of steel dual-lintel column (SDC) joints in Chinese traditional style buildings. Two SDC interior joints and two SDC exterior joints, which consisted of dual box-section lintels, circular column and square column, were designed and tested under low cyclic loading. The force transferring mechanisms at the panel zone of SDC joints were proposed. And also, the load-strain curves at the panel zone, failure modes, hysteretic loops and skeleton curves of the joints were analyzed. It is shown that the typical failure modes of the joints are shear buckling at bottom panel zone, bending failure at middle panel zone, welds fracturing at the panel zone, and tension failure of base metal in the heat-affected zone of the joints. The ultimate bearing capacity of SDC joints appears to decrease with the increment of axial compression ratio. However, the bearing capacities of exterior joints are lower than those of interior joints at the same axial compression ratio. In order to predict the formulas of the bending capacity at the middle panel zone and the shear capacity at the bottom panel zone, the calculation model and the stress state of the element at the panel zone of SDC joints were studied. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the analysis and design of SDC joints in Chinese traditional style buildings.

Key Words
Chinese traditional style building; low cyclic loading; bending capacity; shear bearing capacity; steel dual-lintel column joints

Address
College of Civil Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.



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