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CONTENTS
Volume 44, Number 1, July10 2022
 

Abstract
The weld quality has always been an important factor affecting the development of exposed CFT column-base joint. In this paper, a new type of exposed RCFST column-base joint is proposed, in which the high strength steel bars (USD 685) are set through the column and reinforced concrete foundation without any base plate and anchor bolts. Three specimens, the varying axial force ratio (0, 0.25 and 0.5), were tested under cyclic loadings. In addition, the bending moment capacity, energy dissipation capacity and deformation capacity of column-base joints were clarified. The experimental results indicated that the axial force ratio increases the stiffness and the bending moment and improves the energy dissipation capacity of column-base joints. This is because a large axial force can limit the slip between steel tubular and infilled concrete effectively. The specimens show stable hysteresis behavior.

Key Words
axial force ratio; column base joint; cyclic loading test; slip effect; ultrahigh-strength steel ba

Address
Ben Mou, Zian Wang and Wanqiu Zhou:School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China

Qiyun Qiao:College of Architecture and Civil Engineering, Beijing University of Technology, Beijing, 100124, P.R. Chin

Abstract
This investigation studies the characteristics of wave dispersion in sigmoid functionally graded (SFG) curved beams lying on an elastic substrate for the first time. Homogenization process was performed with the help of sigmoid function and two power laws. Moreover, various materials such as Zirconia, Alumina, Monel and Nickel steel were explored as curved beams materials. In addition, curved beams were rested on an elastic substrate which was modelled based on Winkler–Pasternak foundation. The SFG curved beams'governing equations were derived according to Euler-Bernoulli curved beam theory which is known as classic beam theory and Hamilton's principle. The resulted governing equations were solved via an analytical method. In order to validate the utilized method, the obtained outcomes were compared with other researches. Finally, the influences of various parameters, including wave number, opening angle, gradient index, Winkler coefficient and Pasternak coefficient were evaluated and indicated in the form of diagrams.

Key Words
elastic substrate; Euler-Bernoulli curved beam theory; sigmoid functionally graded; wave dispersion analysis

Address
Linyun Zhou: School of Transportation, Southeast University, Nanjing 210096, Jiangsu, China

Zohre Moradi:1) Faculty of Engineering and Technology, Department of Electrical Engineering,
Imam Khomeini International University, 34149-16818 Qazvin, Iran 2) Department of Biomaterials, Saveetha Dental College and Hospital,
Saveetha Institute of Medical and Technical Sciences, Chennai 600 077, India

Haneen M. Al-Tamimi:Air Conditioning and Refrigeration Techniques Engineering Department, Al-Mustaqbal University College, Babylon, Iraq

H. Elhosiny Ali:1) Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science,
King Khalid University, P.O. Box 9004, Abha, Saudi Arabia
2) Research Center for Advanced Materials Science (RCAMS), King Khalid University, Abha 61413, P.O. Box 9004, Saudi Arabia
3) Physics Department, Faculty of Science, Zagazig University, 44519 Zagazig, Egypt

Abstract
This paper presents a finite element model for predicting the monotonic behaviour of bolted endplate joints connecting steel-concrete composite walls and steel beams. The demountable Hollo-bolts are utilised to facilitate the quick installation and dismantling for replacement and reuse. In the developed model, material and geometric nonlinearities were included. The accuracy of the developed model was assessed by comparing the numerical results with previous experimental tests on hollow/composite column-to-steel beam joints that incorporated endplates and Hollo-bolts. In particular, the Hollo-bolts were modelled with the expanded sleeves involved, and different material properties of the Hollo-bolt shank and sleeves were considered based on the information provided by the manufacture. The developed models, therefore, can be applied in the present study to simulate the wall-to-beam joints with similar structural components and characteristics. Based on the validated model, the authors herein compared the behaviour of wall-to-beam joints of two commonly utilised composite walling systems (Case 1: flat steel plates with headed studs; Case 2: lipped channel section with partition plates). Considering the ease of manufacturing, onsite erection and the pertinent costs, composite walling system with flat steel plates and conventional headed studs (Case 1) was the focus of present study. Specifically, additional headed studs were pre-welded inside the front wall plates to enhance the joint performance. On this basis, a series of parametric studies were conducted to assess the influences of five design parameters on the behaviour of bolted endplate wall-to-beam joints. The initial stiffness, plastic moment capacity, as well as the rotational capacity of the composite wall-to-beam joints based on the numerical analysis were further compared with the current design provision.

Key Words
composite walls; design methods; endplate bolted joints; numerical modelling; steel beams

Address
Dongxu Li, Brian Uy, Jun Mo:School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia

Huu-Tai Thai:Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC 3010, Australia

Abstract
This study aims to develop ensemble machine learning (ML) models for estimating the peak floor acceleration and maximum top drift of steel moment frames. For this purpose, random forest, adaptive boosting, gradient boosting regression tree (GBRT), and extreme gradient boosting (XGBoost) models were considered. A total of 621 steel moment frames were analyzed under 240 ground motions using OpenSees software to generate the dataset for ML models. From the results, the GBRT and XGBoost models exhibited the highest performance for predicting peak floor acceleration and maximum top drift, respectively. The significance of each input variable on the prediction was examined using the best-performing models and Shapley additive explanations approach (SHAP). It turned out that the peak ground acceleration had the most significant impact on the peak floor acceleration prediction. Meanwhile, the spectral accelerations at 1 and 2 s had the most considerable influence on the maximum top drift prediction. Finally, a graphical user interface module was created that places a pioneering step for the application of ML to estimate the seismic demands of building structures in practical design.

Key Words
earthquake engineering; ensemble learning models; machine learning; seismic demands; steel moment frames

Address
Hoang D. Nguyen:Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil,
Eonyang-eup, Ulju-gun, Ulsan, South Korea

JunHee Kim:Department of Architecture and Architectural Engineering, Yonsei University, 50 Yonseiro, Seadaemun-gu, Seoul 120-749, South Korea

Myoungsu Shin:Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil,
Eonyang-eup, Ulju-gun, Ulsan, South Korea


Abstract
The main goal of this paper is to study the vibration of damaged core laminated annular plates with FG face sheets based on a three-dimensional theory of elasticity. The structures are made of a damaged isotropic core and two external face sheets. These skins are strengthened at the nanoscale level by randomly oriented Carbon nanotubes (CNTs) and are reinforced at the microscale stage by oriented straight fibers. These reinforcing phases are included in a polymer matrix and a three-phase approach based on the Eshelby-Mori-Tanaka scheme and on the Halpin-Tsai approach, which is developed to compute the overall mechanical properties of the composite material. In this study the effect of microcracks on the vibrational characteristic of the sandwich plate is considered. In particular, the structures are made by an isotropic core that undergoes a progressive uniform damage, which is modeled as a decay of the mechanical properties expressed in terms of engineering constants. These defects are uniformly distributed and affect the central layer of the plates independently from the direction, this phenomenon is known as "isotropic damage" and it is fully described by a scalar parameter. Three complicated equations of motion for the sectorial plates under consideration are semi-analytically solved by using 2-D differential quadrature method. Using the 2-D differential quadrature method in the r- and z-directions, allows one to deal with sandwich annular plate with arbitrary thickness distribution of material properties and also to implement the effects of different boundary conditions of the structure efficiently and in an exact manner. The fast rate of convergence and accuracy of the method are investigated through the different solved examples. The sandwich annular plate is assumed to have any arbitrary boundary conditions at the circular edges including simply supported, clamped and, free. Several parametric analyses are carried out to investigate the mechanical behavior of these multi-layered structures depending on the damage features, through-the-thickness distribution, and boundary conditions.

Key Words
2-D differential quadrature method; damaged isotropic core; Eshelby-Mori-Tanaka scheme; Halpin-Tsai equation; laminated sectorial plates; three-dimensional theory of elasticity

Address
Fei Xi:School of Art and Design, Nanjing University of Finance & Economics, Jiangsu Nanjing, 210023, China

Abstract
The purposes of the present work it to study the effect of shear deformation on the static post-buckling response of simply supported functionally graded (FGM) axisymmetric beams based on classical, first-order, and higher-order shear deformation theories. The behavior of postbuckling is introduced based on geometric nonlinearity. The material properties of functionally graded materials (FGM) are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents. The equations of motion and the boundary conditions derived using Hamilton's principle. This article compares and addresses the efficiency, the applicability, and the limits of classical models, higher order models (CLT, FSDT, and HSDT) for the static post-buckling response of an asymmetrically simply supported FGM beam. The amplitude of the static post-buckling obtained a solving the nonlinear governing equations. The results showing the variation of the maximum post-buckling amplitude with the applied axial load presented, for different theory and different parameters of material and geometry. In conclusion: The shear effect found to have a significant contribution to the post-buckling behaviors of axisymmetric beams. As well as the classical beam theory CBT, underestimate the shear effect compared to higher order shear deformation theories HSDT.

Key Words
amplitude; axisymmetric beams; buckling; classical theory; functionally graded beams; post buckling

Address
Ali Meksi:Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie,
Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie

Hadj Youzera:Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie,
Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie

Mohamed Sadoun:Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie,
Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie

Ali Abbache:Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbes, Alegria

Sid Ahmed Meftah:Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbes, Alegria

Abdelouahed Tounsi:YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
4Department of Civil and Environmental Engineering, King Fahd University of Petroleum and Minerals,
Dhahran, 31261, Eastern Province, Saudi Arabia
5Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
6Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan

Muzamal Hussain:Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan

Abstract
The purpose of the present work is to study the parametric nonlinear vibration behavior of three layered symmetric laminated plate. In the analytical formulation; both normal and shear deformations are considered in the core layer by means of the refined higher-order zig-zag theory. Harmonic balance method in conjunction with Galerkin procedure is adopted for simply supported laminate plate, to obtain its natural and damping properties. For these aims, a set of complex amplitude equations governed by complex parameters are written accounting for the geometric nonlinearity and viscoelastic damping factor. The frequency response curves are presented and discussed by varying the material and geometric properties of the core layer.

Key Words
composite material; Galerkin Method; harmonic balance method; nonlinear vibration; sandwich plates

Address
Hadj Youzera:Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie,
Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie

Abbache Ali:1)Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie,
Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie
2)Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbes, Alegria

Sid Ahmed Meftah:Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbes, Alegria

Abdelouahed Tounsi:1)YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
2)Department of Civil and Environmental Engineering, King Fahd University of Petroleum and Minerals,
Dhahran, 31261, Eastern Province, Saudi Arabia
3)Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology,
Civil Engineering Department , Algeria

Muzamal Hussain:Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan


Abstract
Impact resistance efficiency of the newly designed sandwich beam with a laterally arched core as bio-inspired by the woodpecker is numerically investigated. The principal components of the beam comprise a dual-core system sandwiched by the top and bottom laminated CFRP skins. Different materials, including hot melt adhesive, high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), epoxy resin (EPON862), aluminum (Al6061), and mild carbon steel (AISI1018), are considered for the side-arched core layer of the beam for impact efficiency assessment. The aluminum honeycomb takes the role of the second core. Contact force, stress, damage formation, and impact energy for beams equipped with different materials are examined. A diversity in performance superiority is noticed in each of these indicators for different core materials. Therefore, for overall performance appraisal, the impact resistance efficiency index, which covers several chief impact performance parameters, of each sandwich beam is computed and compared. The impact resistance efficiency index of the structure equipped with the AISI1018 core is found to be the highest, about 3-10 times greater than other specimens, thus demonstrating its efficacy as the optimal material for the bio-inspired dual-core sandwich beam system.

Key Words
arched core; bio-inspired; composite structure; computational simulation; impact resistance efficiency; impact; sandwich beam

Address
Ahmad B.H. Kueh:1)Department of Civil Engineering, Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia
2)UNIMAS Water Centre (UWC), Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia

Chun-Yean Tan:United Ivory Sdn Bhd, 14000 Bukit Mertajam, Pulau Pinang, Malaysia

Mohd Yazid Yahya:Centre for Advanced Composite Materials (CACM), School of Mechanical Engineering, Faculty of Engineering, Universiti Teknologi
Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia

Mat Uzir Wahit:School of Chemical and Energy Engineering, Faculty of Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor,
Malaysia


Abstract
This paper aims to use the artificial intelligence approach to develop a new model for predicting the ultimate axial strength of the circular concrete-filled steel tubular (CFST) stub columns. For this, the results of 314 experimentally tested circular CFST stub columns were employed in the generation of the design model. Since the influence of the column diameter, steel tube thickness, concrete compressive strength, steel tube yield strength, and column length on the ultimate axial strengths of columns were investigated in these experimental studies, here, in the development of the design model, these variables were taken into account as input parameters. The model was developed using the backpropagation algorithm named Bayesian Regularization. The accuracy, reliability, and consistency of the developed model were evaluated statistically, and also the design formulae given in the codes (EC4, ACI, AS, AIJ, and AISC) and the previous empirical formulations proposed by other researchers were used for the validation and comparison purposes. Based on this evaluation, it can be expressed that the developed design model has a strong and reliable prediction performance with a considerably high coefficient of determination (R-squared) value of 0.9994 and a low average percent error of 4.61. Besides, the sensitivity of the developed model was also monitored in terms of dimensional properties of columns and mechanical characteristics of materials. As a consequence, it can be stated that for the design of the ultimate axial capacity of the circular CFST stub columns, a novel artificial intelligence-based design model with a good and robust prediction performance was proposed herein.

Key Words
CFST column; code formula; design model; artificial neural network; stub column

Address
Süleyman İpek:Department of Architecture, Bingol University, 12000, Bingöl, Turkey

Ayşegül Erdoğan:Department of Civil Engineering, Gaziantep University, 27310, Gaziantep, Turkey

Esra Mete Güneyisi:Department of Civil Engineering, Gaziantep University, 27310, Gaziantep, Turkey



Abstract
This paper describes the experimental and numerical investigation on circular and octagonal CFDST short columns under concentric loading to study their responses to various internal circular steel tube sizes by the constant cross-sectional dimensions of the external circular and octagonal steel tube. The non-linear finite element analysis of circular and octagonal CFDST columns was executed using the ABAQUS to forecast and compare the axial behavior influenced by the various sizes of internal circular steel tubes. The study shows that the axial compressive strength and ductility of circular and octagonal CFDST columns were significantly influenced by inner steel tubes with the strengths of constituent materials.

Key Words
ABAQUS; axial response; circular CFDST column; composite column; finite element analysis; octagonal CFDST column; sandwiched concrete

Address
Manigandan R, Manoj Kumar and Hrishikesh N. Shedge:Department of Civil Engineering, Birla Institute of Technology and Science, Pilani (BITS Pilani), Vidya Vihar, Rajasthan 333 301, India

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