Abstract
Coconut fibre is low carbon and environmentally friendly and has a low cost, relatively high strength and toughness, and can be incorporated into concrete to improve the latter's resistance to high-temperature bursting. In this study, an appropriate amount of coconut fibre was added to coral concrete to simultaneously solve the problems of low early strength, large shrinkage and poor resistance to high-temperature bursting of coral concrete and to initially establish the theoretical system of coconut fibre-reinforced coral concrete (CF-CC) to lay a theoretical foundation for solving the intrinsic defects of coral concrete and expanding its engineering applications. The results show that there is no obvious cracking in the specimen above 700oC.At 900oC, many cracks penetrated the specimen. At 20–100oC, the specimen mass loss was very low. At 300oC, the specimen mass loss rate was approximately 9%. Afterwards, the change in mass loss rate with temperature was relatively small. The compressive strength peaked at 100oC, with a maximum increase of nearly 10%, and decreased considerably at 300oC, with a maximum decrease of 16.5%. At 500oC, the average compressive strength decreased by approximately 10%. The compressive strength–temperature curve tended to stabilise. At 20oC, the addition of coconut fibres with densities of 3–4.5 kg/m3 considerably enhanced the tensile strength, with a maximum increase of approximately 20%. Then, at 100oC, the addition of coconut fibre slightly increased the coral concrete tensile strength, with a maximum increase of 7.5%. Above 100oC, coconut fibre minimally affected the coral concrete tensile strength.
Key Words
coconut fibre; coral concrete; high temperature; mechanical properties; numerical fitting
Address
Cunpeng Liu: Department of Civil and Surveying Engineering, Guilin University of Technology at Nanning, 530001, Nanning, Guangxi, China; School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia
Fatimah De'nan: School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300, Nibong Tebal, Pulau Pinang, Malaysia
Pengyong Deng: Department of Civil and Architectural Engineering, Guangxi Transport Vocational and Technical College, 530023, Nanning, Guangxi, China
Qian Mo: Department of Civil and Architectural Engineering, Guangxi Transport Vocational and Technical College, 530023, Nanning, Guangxi, China
Dalian Bai: Department of Civil and Surveying Engineering, Guilin University of Technology at Nanning, 530001, Nanning, Guangxi, China
Li Liang: Department of Civil and Architectural Engineering, Guangxi Transport Vocational and Technical College, 530023, Nanning, Guangxi, China
Abstract
This work is related to an analysis of size-dependent buckling behavior of functionally graded carbon nanotubesreinforced composite (FG-CNTRC) nano-plates. The nano-plate is reinforced by single-walled carbon nanotubes (SWCNTs), which are embedded in a polymer matrix with four different reinforcement distributions. A size-dependent mathematical model for the FG-CNTRC nano-plate is developed by combining the higher-order shear deformation plate theory (HoSDPT) with the nonlocal strain gradient theory. Analytical solutions for the critical buckling forces of FG-CNTRC nano-plates under three different boundary conditions are obtained. The accuracy of the current solutions is validated through numerical comparisons with existing results in the literature. The effects of some key parameters, including the volume fraction of SWCNTs, aspect ratios, nonlocal parameter, and material length scale parameter on the buckling behavior of FG-CNTRC nano-plates are investigated and discussed.
Key Words
buckling analysis; carbon nanotubes; nano-plates; nonlocal strain gradient
Address
Dang Van Hieu: Department of Applied Mechanics, Faculty of Vehicle and Energy Engineering, Thai Nguyen University of Technology, Thainguyen, Vietnam; Faculty of Mechanical Engineering and Mechatronics, Phenikaa University, Hanoi, Vietnam
Nguyen Thi Hoa, Nguyen Thi Kim Thoa: Department of Applied Mechanics, Faculty of Vehicle and Energy Engineering, Thai Nguyen University of Technology, Thainguyen, Vietnam
Abstract
The fundamental natural period of a building is its most important dynamic characteristic parameter, influenced by many factors. Various building codes provide empirical formulas for period prediction, however, these typically consider only one or two factors, such as building height and material type, while ignoring the effects of others. Data-driven Automated Machine Learning (AutoML) offers a novel approach to quickly develop powerful predictive models while avoiding the tedious and time consuming iterative tasks involved in traditional machine learning model development. This study establishes a database comprising full-scale measured period samples from more than 3,000 existing buildings, obtained through a rigorous literature search and data filtering process. The AutoGluon Python package is employed to develop a robust predictive model with ten influencing factors, including five numerical features and five categorical features, as inputs. Compared to empirical formulas in building codes and those proposed by researchers, the proposed AutoML model demonstrates better accuracy across a wider range of building types. A coefficient of determination of 0.93 on the test set is achieved, and the model's generalization capability is validated using independent third-party measurement data. Furthermore, the proposed model is deployed online and made openly accessible for quick, reliable predictions.
Key Words
AutoML; machine learning; model interpretability; natural period; predictive model
Address
Kawsu Jitteh, Yinghao Song, Yang Li, Jun Chen: College of Civil Engineering, Tongji University, Shanghai, 200092, China
Zetao Wang: Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong
Ahmed Amine Daikh, Oussama Djedidi, Omar Allali, Mohamed Ouejdi Belarbi, Loubna Nadji, Mohammed Sid Ahmed Houari, Mohamed A. Eltaher and Azza M. Abdraboh
Abstract
This paper explores the buckling behavior of advanced composite nanoshells composed of functionally graded
materials, such as porous metal form nanoshells, employing higher-order shear deformation theory, nonlocal strain gradient theory, and the principle of virtual work. The study applies the Galerkin method to analyze different boundary conditions. Mathematical formulations are developed to predict buckling loads and modes in FGM nanoshells under various conditions, incorporating considerations of material gradients and geometrical configurations. The results obtained from calculations are presented and discussed, detailing critical buckling loads and the impact of geometric and material parameters on the structural stability of FGM nanoshells. These findings contribute to advancing the understanding of buckling phenomena in nanoscale composite structures and provide insights for optimizing their mechanical performance in practical engineering applications.
Key Words
buckling behavior; FG porous metal foam; Galerkin technique; higher-order shear deformation theory; nonlocal strain gradient theory
Address
Ahmed Amine Daikh: Artificial Intelligence Laboratory for Mechanical and Civil Structures, and Soil, University Centre of Naama, P.O. Box 66, Naama 45000, Algeria
Oussama Djedidi: Department of Mechanical Engineering, University Centre of Naama, P.O. Box 66, Naama 45000, Algeria
Omar Allali: Department of Mechanical Engineering, University Centre of Naama, P.O. Box 66, Naama 45000, Algeria
Mohamed Ouejdi Belarbi: Laboratoire de Recherche en Génie Civil, LRGC, Université de Biskra, B.P. 145, R.P. 07000, Biskra, Algeria
Loubna Nadji: Artificial Intelligence Laboratory for Mechanical and Civil Structures, and Soil, University Centre of Naama, P.O. Box 66, Naama 45000, Algeria
Mohammed Sid Ahmed Houari: 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 A. Eltaher: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University (KAU),
P.O. Box 80204, Jeddah, Saudi Arabia; Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, P.O. Box 44519, Zagazig, Egypt
Azza M. Abdraboh: Physics Department, Faculty of Science, Benha University, Benha, Egypt
Abstract
Beam-to-column connections with end plates exhibit complex interfacial behavior during the loading phase. The contact surfaces evolve progressively into three distinct zones: adherent, slipping, and separated. However, the precise delimitation of these zones remains a challenge because relevant techniques seem specifically insufficient. Our developments using a discrete formulation highlighted the numerical difficulties related to this delimitation. However, a comprehensive characterization of the evolution of these zones was made possible by adding additional kinematic conditions established a posteriori and compared to a detachment threshold whose choice is based on numerically observed similarities. Subsequently, the influence of certain important parameters on the detachment rate was estimated.
Key Words
contact behavior; detachment rate; end plate connection; finite elements; parametric analysis; similarities
Address
Abdelhamid Becheur: Research Laboratory of Applied Hydraulic and Environment LRHAE, Faculty of Technology, University of Bejaia, Bejaia, 06000, Algeria
Patrice Coorevits: EPROAD Research Unit, University of Picardie Jules Verne, IUT of Aisne, Saint Quentin, 02100, France
Abstract
The present work takes the magneto-electro-elastic (MEE) beams as the research object, considers the influence of initial geometrical imperfection, and studies the thermal buckling and forced vibration behavior of MEE beams. A nonlinear dynamic model for MEE beams is established based on Euler beam theory. The nonlinear partial differential equations are discretized using the analytical method to solve forced vibration and thermal buckling responses. Finally, the influence of different parameters on the thermal buckling and forced vibration behavior of MEE beams with initial geometrical imperfection is analyzed through numerical analysis. The results show that appropriately reducing the volume fraction of BaTiO3 improves the vibration suppression performance of the beam, while increasing the magnetic potential coefficient or decreasing the damping coefficient enhances the vibration suppression performance under different conditions. Increasing the magnetic potential and decreasing the electric potential amplify the buckling behaviors of MEE beams. However, the MEE beam model exhibits reduced sensitivity to buckling responses when the aspect ratio is small.
Address
G.L. She, L.L. Gan, Y.J. He: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China
H.B. Liu: College of Mechanical and Electric Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China
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