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CONTENTS
Volume 40, Number 3, August10 2021
 


Abstract
To study the track irregularity spectrum for CRTS II ballastless track continuous girder bridge for high-speed railway (CBTCGB) after the action of earthquake, a line-bridge integration seismic calculation model was established. By considering the randomness of structural parameters and ground motion, large amounts of samples were analyzed for additional track irregularity caused by factors such as earthquake-induced damage and earthquake-induced void of key components between the layers of track-bridge system. Using improved Blackman-Turkey method and Levenberg- Marquardt algorithm, the earthquake damaged CBTCGB track irregularity spectrum, track irregularity spectrogram, and a fitting formula for track irregularity spectrum after the action of near-field earthquake were obtained, and the calculation results obtained from the fitting formula and CBTCGB numerical model were compared. The results indicate that the probability sampling distribution of ground motion and structural parameters selected according to "binning method" can effectively reflect the randomness of ground motion and structural parameters. The track irregularity spectrum line forms can be roughly divided into three ranges, namely, high-frequency, medium-frequency, and low-frequency waveband. The tracks suffer more track irregularity diseases with high-frequency after earthquake, which is necessary to conduct tracking analysis. It is rational to use a three-segment power function for the fitting of track irregularity spectrum after the action of earthquake.

Key Words
goodness of fit; high-speed railway; Levenberg-Marquardt; track irregularity spectrum

Address
Yulin Feng: School of Civil Engineering, Central South University, Changsha, 410075, China;
School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China;
State key laboratory of performance monitoring and guarantee of rail transportation infrastructure, Nanchang 330013, China
Lizhong Jiang and Wangbao Zhou: School of Civil Engineering, Central South University, Changsha, 410075, China
National Engineering Laboratory for High Speed Railway Construction, Changsha, 410075, China
Mengcheng Chen: School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China;
State key laboratory of performance monitoring and guarantee of rail transportation infrastructure, Nanchang 330013, China

Abstract
In this paper, the axial compressive properties of cold-formed steel lipped channel stub columns strengthened by rebars or steel strips are experimentally studied. The experiment included two sections. A kind of columns with local buckling is reinforced longitudinally by steel strips at the web. The other is the columns with distorted buckling, which is reinforced longitudinally by steel bars at the curling edge. The failure mode, deformation characteristics, ultimate bearing capacity and load displacement curve of the specimen are obtained through the experiment. On the basis of the experiment, the calculation results of theoretical axial bearing capacity of cold-formed steel lipped channel stub columns in Chinese, North American and Australian code are compared and analyzed. Research indicates: First, the cold-formed steel lipped channel stub columns strengthened by steel bars or steel strips can effectively improve the compressive bearing capacity of the specimen. Secondly, when the initial stress ratio of specimen is less than 0.3, the reinforcement effect is ideal. Thirdly, the three standards don't stipulate the calculation of theoretical bearing capacity of the specimen strengthened after loading, so there is a large deviation between the theoretical calculation value and the test value.

Key Words
axial pressure test; carrying capacity; cold-formed steel lipped channel stub column; initial stress; reinforced with steel bars or steel strips

Address
Jian-Feng Chen, Ming-Qi Chen and Xin-Xin Yang: School of Civil Engineering, Chang'an University, Xi'an 710061, China
Yong-Kang Shen: School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Xi'an 710048, China
Jian-Hua Shao: Experimental Center of School of Civil Engineering and architecture,
Jiangsu University of Science and Technology, Zhenjiang 212003, China


Abstract
The current work fills a gap of a small-scale study on wave propagation behavior of symmetric, antisymmetric, and quasi-isotropic cross/angle-plies laminated composite nanoplates. The governing equations are derived through the Hamiltonian principle for four-variable refined shear deformation plate theory in conjunction with the assumption of a non-classical theory, and then size-dependent formulations are solved via an analytical solution procedure. This work provides information to accurately analyze the influence of lay-up numbers and sequences, geometry, fiber orientations, and wave numbers on the size-dependent wave propagation response of laminated composite nanoplates.

Key Words
laminated composite nanoplate; nonlocality; strain gradient size-dependency; wave propagation

Address
Xinli Xu and Chunwei Zhang: Structural Vibration Control Group, Qingdao University of Technology, Qingdao 266033, China
Farayi Musharavati: Department of Mechanical and Industrial Engineering Qatar University, P.O. Box 2713, Doha, Qatar
Tamer A. Sebaey: Engineering Management Department, College of Engineering, Prince Sultan University, Riyadh, Saudi Arabia;
Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Sharkia, Egypt
Afrasyab Khan: Institute of Engineering and Technology, Department of Hydraulics and Hydraulic and Pneumatic Systems, South Ural State University, Lenin Prospect 76, Chelyabinsk, 454080, Russian Federation



Abstract
This investigation contributes to quantification of the inelastic seismic demands for high strength steel moment resisting frames equipped with energy dissipation bays (HSSF-EDBs) subjected to seismic sequences composed of repeated near-field ground motions. The emphasis is placed on the energy factor demand. A statistical examination of a database with more than eighty million energy factor demands of single-degree-of-freedom (SDOF) oscillators representing HSSF-EDBs responding in different yielding stages is conducted. The research findings show that in the damage-control stage, the energy factor which quantifies the peak seismic demand of a HSSF-EDB structure is insensitive to the repeated near-field earthquake motions. In contrast, a remarkable elevation of the energy factor is observed when oscillators characterising HSSF-EDBs progress into the ultimate stage. In addition, an increasing post-yielding stiffness ratio of the nonlinear force-displacement response in the damage-control stage may produce a detrimental effect on HSSF-EDBs progressing into the ultimate stage under repeated near-field earthquakes due to the corresponding evident increase of seismic demands. A nonlinear regression model quantifying the mean energy factor demand of the system under repeated near-field earthquake motions is proposed to facilitate performance-based seismic design of HSSF-EDBs.

Key Words
energy balance; energy dissipation bay; high strength steel; inelastic seismic demands; repeated near-field earthquake

Address
Ke Ke, Xuhong Zhou and Fei Xu: Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing University, Chongqing, China;
School of Civil Engineering, Chongqing University, Chongqing, China
Michael CH Yam: Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China;
Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch),
The Hong Kong Polytechnic University, Hong Kong, China
Fuming Wang: Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing University, Chongqing, China



Abstract
This paper introduces a comprehensive buckling response of cross-ply orientation of carbon nanotube reinforced composite (CNTRC) multilayered nanobeams with different boundary conditions. The nonlocal strain gradient (NLSG) stress-strain governing relations are utilized to include the size-dependence and microstructure effects. Novel hyperbolic higher shear deformation beam theory including thickness stretching effect is used to fulfill both parabolic shear distribution through the thickness and the zero-shear at free boundaries. Parametric studies are performed to inspect the influences of arrangement of reinforcement material distributions functions, different functionally graded (FG) functions, and uniform distribution (UD). The balance equilibrium equations are derived, and Fourier functions are utilized to obtain the critical buckling loads of nanobeam under mechanical loadings. Mechanical properties are assumed to be temperature-dependent by using Touloukian principal. An exact solution is performed satisfying the edge boundary conditions. A detailed numerical analysis is illustrated to examine the impact of CNTs patterns, lamination, side-to-thickness, aspect ratios, microstructure and size scale parameters on critical buckling loads of CNTRC laminated nanobeams.

Key Words
buckling; CNTRC laminated nanobeams; cross-ply; nonlocal strain gradient theory; quasi-2D higher-order shear; various boundary conditions

Address
Mashhour A. Alazwari: Mechanical Engineering Dept., Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia
Ahmed Amine Daikh and Mohammed Sid Ahmed Houari: Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Department of Civil Engineering, Mascara, Algeria
Abdelouahed Tounsi: Department of Civil and Environmental Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261,
Eastern Province, Saudi Arabia;
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea;
Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes,
Sidi Bel Abbes, Algeria;
Mohamed A. Eltaher: Mechanical Engineering Dept., Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, Saudi Arabia;
Mechanical Design and Prod. Dept., Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt


Abstract
This paper experimentally investigated the behavior of a cross-shaped concrete-filled steel tubular (C-CFST) column subjected to a constant axial load and a low-cycle repeated loading. Nine C-CFST columns with different length-width ratio, width-thickness ratio and axial compression ratio were designed, and the failure mode, hysteresis curve, skeleton curve, ductility, stiffness degradation and energy dissipation capacity of each specimen were studied and analyzed. The results indicated that the cross-shaped steel tube had a strong restraining effect on the core concrete, and C-CFST columns of different sectional dimensions all exhibited favorable seismic behavior, which is suitable for middle-high residential buildings. An increase of length-width ratio enhanced the initial stiffness with a decrease of ductility, and more rapid stiffness degradation during loading. Specimens with smaller width-thickness ratios had higher ductility, stiffness, and energy dissipation capacity. A larger axial compression ratio could reduce the bearing capacity, and cause the stiffness to degrade faster. Moreover, a hysteretic model of C-CFST columns was also proposed based on an analysis of the test results.

Key Words
axial compression ratio; cross-shaped concrete-filled steel tubular column; cyclic loading; hysteretic model; length-width ratio; width-thickness ratio

Address
Ji-Cheng Zhang, Xiao-Yu Liu, Lei Zeng, Guo-Feng Du and Jia-Hao Xiao: School of Urban Construction, Yangtze University, Jingzhou 434023, China

Abstract
Tensile tests were carried out on the single-lap countersunk composite joints with metallic bushing, and the load-displacement curves, strains and damage morphologies around the bolt hole were measured. A 3D progressive damage finite element model (FEM) was established in ABAQUS/Standard and verified by experimental results. Based on the validated model, tensile performances of the joints were investigated, including damage mechanism analysis of the laminate and the effect discussion of bushing thickness, tightening torque, interference fit size and etc. The results show that metallic bushing can improve ultimate bearing load of the joints. The stress distribution and initial damages caused by assembly around the laminate hole are little affected by bushing thickness. Appropriate tightening torque and interference fit size can improve tensile performances of the joint.

Key Words
bearing load; countersunk composite joints; interference fit; metallic bushing; tightening torque

Address
Xiaoquan Cheng: School of Aeronautic Science and Engineering, Beihang University, Beijing 100083, China
Xiaoyuan Du: School of Aeronautic Science and Engineering, Beihang University, Beijing 100083, China;
The 28th Research Institute of China Electronics Technology Group Corporation, Nanjing 210007, China
Kun Chen: School of Aeronautic Science and Engineering, Beihang University, Beijing 100083, China;
The Second System Design Department of the Second Research Academy of CASIC, Beijing 100854, China
Maosheng Shu and Xiaodong Liu: AVIC Chengdu Aircraft Design and Research Institute, Chengdu 610041, China
Gang Chen: The Second System Design Department of the Second Research Academy of CASIC, Beijing 100854, China


Abstract
The self-centering system and yielding energy dissipation system are two main parts of self-centering buckling-restrained braces (SC-BRBs), which have important influences on brace performance. To improve the performance of the two parts, an SC-BRB with composite tendons in series (SC-BRB-CTS) is proposed by introducing a self-centering system in series that can improve the deformation capability of the brace, and the yielding energy dissipation system made of low-yield steel LYP160 with a strong energy dissipation capacity is adopted. The performance of the braces is studied by quasi-static tests, and the influence of the self-centering system in series and low-yield steel on the seismic performance of the structure is determined by nonlinear dynamic analyses and fragility analyses. The results show that the deformation capacity of the SC-BRB-CTS is approximately 44% higher than that of a traditional SC-BRB, and the collapse resistance of the structure is improved by avoiding or delaying tendon fracture. The use of LYP160 steel core plates can substantially improve the energy dissipation capacity and post-yielding bearing capacity of the brace, which is beneficial for reducing the seismic response of the structure.

Key Words
composite tendons in series; low-yield steel; quasi-static test; seismic response; self-centering

Address
Qin Xie: Institute of Engineering Mechanics, China Earthquake Administration;
Key Laboratory of Earthquake Engineering and Engineering Vibration of China Earthquake Administration, Harbin, 150080, China
Zhen Zhou: Southeast University, Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Nanjing, 210096, China
Lingxin Zhang: Institute of Engineering Mechanics, China Earthquake Administration;
Key Laboratory of Earthquake Engineering and Engineering Vibration of China Earthquake Administration, Harbin, 150080, China




Abstract
In this paper, buckling analyses of composite plate reinforced by Graphen platelate (GPL) is studied. The Halphin-Tsai model is used for obtaining the effective material properties of nano composite plate. The nano composite plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of plate are obtained and using Hamilton's principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of GPL volume percent, geometrical parameters of plate and elastic foundation on the buckling load are investigated. Results showed that with increasing GPLs volume percent, the buckling load increases.

Key Words
buckling; graphen platelate; halphin-Tsai model; nanocomposite plate; reddy theory

Address
Ran Bi: Department of Civil and Architectural Engineering, Xi'an University of Science and Technology, Xi'an,
Shaanxi, 710054, China
Jun Gao: Department of Civil Engineering, Tsinghua University, Haidian 100083, Beijing, China;
National Railway Group Wu guang High Railway Company, Wuhan 430212, Hubei, China
Seyedmahmoodreza Allahyari: Department of Mechanical Engineering, Dariun Branch, Islamic Azad University, Dariun, Iran


Abstract
This study aims to propose a new intelligence technique of predicting the ultimate capacity of axially loaded circular concrete-filled steel tube (CCFST) columns. A hybrid system based on one of the evolution algorithm – Genetic Algorithm (GA), fused with a well-known data-driven model of multivariate adaptive regression splines (MARS), namely G-MARS, was proposed and applied. To construct the MARS model, a database of 504 experimental cases was collected from the available literature. The GA was utilized to determine an optimal set of MARS's hyperparameters, to improve the prediction accuracy. The compiled database covered five input variables, including the diameter of the circular cross section-section (D), the wall thickness of the steel tube (t), the length of the column (L), the compressive strength of the concrete (fc), and the yield strength of the steel tube (fy). A new explicit formulation was derived from MARS in further analysis, and its estimation accuracy was validated against a benchmark model, G-ANN, an artificial neural network (ANN) optimized using the same metaheuristic algorithm. The simulation results in terms of error range and statistical indices indicated that the derived formula had a superior capability in predicting the ultimate capacity of CCFST columns, relative to the G-ANN model and the other existing empirical methods.

Key Words
CCFST; concrete-filled steel tube column; evolutionary hybrid model; genetic algorithm; multivariate adaptive regression spline; ultimate capacity

Address
Nguyen-Vu Luat: Department of Architectural Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, South Korea;
Falculty of Civil Engineering, Thuyloi University, 175 Tay Son, Dong Da, Hanoi 100000, Vietnam
Jiuk Shin: epartment of Architectural Engineering, Gyeongsang National University, Jinju 52828, South Korea
Sang Whan Han: Department of Architectural Engineering, Hanyang University, Seoul 04763, South Korea
Ngoc-Vinh Nguyen: Department of Infrastructure Engineering, Vietnam – Japan University, Luu Huu Phuoc, My Dinh 129000, Ha Noi, Viet Nam
Kihak Lee: Department of Architectural Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 05006, South Korea



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