Techno Press
Tp_Editing System.E (TES.E)
Login Search
You logged in as

cac
 
CONTENTS
Volume 33, Number 1, January 2024
 

Abstract
Aggressive environmental conditions, and especially the acidic effects of sulfate ion penetration, have reduced the lifetime of concrete structures in some areas, especially coastal and marine areas. In this research, at first, samples made of type II and V cement were kept in a solution of magnesium sulfate (MgSO4) for a period of 90 and 180 days, the change of appearance. Field Emission Scanning Electron Microscopy (FE-SEM) and X-Ray Diffraction (XRD), were used to analyze the microstructure and the complex mineral composition of the concrete after exposure to corrosive environments. Then solving the differential equation governing the sulfate ion penetration, which is based on the second Fick law, it has been tried to determine the concentration of sulfate ions inside the concrete. In the following, an attempt has been made to improve the prediction of sulfate ion concentration in concrete by using Crank's penetration equation. At the same time, the coefficient in the Crank's solution have been optimized by using the Particle Swarm Optimization (PSO algorithm). The comparison between the results shows that the values obtained from Crank's relation are closer to the experimental results than the equation obtained from Fick's second law and shows a more accurate prediction.

Key Words
concentration of sulfate ion; concrete degradation; Crank's equation; Fick's second law

Address
Mohammad Ghanooni-Bagh and Sajad Momen: Department of Civil Engineering, East Tehran Branch, Islamic Azad University, Tehran, Iran, P.O.BOX: 18735-136
Mohsen Ali Shayanfar: The Centre of Excellence for Fundamental Studies in Structural Engineering, Iran University of Science and Technology, P.O.BOX: 16765-163; Narmak, Tehran, Iran

Abstract
In this study, contact analysis in a functionally graded (FG) layer loaded with two circular punches is solved using the finite element method (FEM). The problem is consisted of a functionally graded layer that resting on an elastic semi-infinite plane and is loaded with two rigid punches of circular geometry. External loads P and Q are transferred to the layer via two rigid punches. The finite element model of the functionally graded layer is created using the ANSYS package program and a 2-dimensional analysis of the problem is analyzed. The contact lengths, obtained as a result of the analysis are compared with the analytical solution in the literature. In the study, the effects of parameters such as distances between punches, loads, inhomogenity parameter on contact zones, initial separation loads and distances, normal stresses, stresses across depth and contact stresses are investigated. As a result, in this study, it can be said that the magnitude of the stresses occurring in the FG layer is less than the homogeneous layer, therefore the life of FG materials will be longer than the homogeneous layer. When the distance between the punches is 2.25, the initial separation distance is 6.98, and when the distance between the punches is 4, the initial separation distance decreases to 6.10. In addition, when the load increased in the second punch, the initial separation load decreased from 55 to 18. The obtained results are presented in the form of graphs and tables.

Key Words
contact length; finite element method; functionally graded layer; stress analysis

Address
Munzur University, Department of Civil Engineering, 62000, Tunceli, Turkey

Abstract
In this study, the authors investigate the free vibration behavior of three-phases functionally graded sandwich plates using a novel nth-order shear deformation theory. These plates are composed of a homogeneous core and two face-sheet layers made of different functionally graded materials. This is the novel type of the sandwich structures that can be applied in many fields of mechanical engineering and industrial. The proposed theory only requires four unknown displacement functions, and the transverse displacement does not need to be separated into bending and shear parts, simplifying the theory. One noteworthy feature of the proposed theory is its ability to capture the parabolic distribution of transverse shear strains and stresses throughout the plate's thickness while ensuring zero values on the two free surfaces. By eliminating the need for shear correction factors, the theory further enhances computational efficiency. Equations of motion are established using Hamilton's principle and solved via Navier's solution. The accuracy and efficiency of the proposed theory are verified by comparing results with available solutions. The authors then use the proposed theory to investigate the free vibration characteristics of three-phases functionally graded sandwich plates, considering the effects of parameters such as aspect ratio, side-to-thickness ratio, skin-core-skin thicknesses, and power-law indexes. Through careful analysis of the free vibration behavior of three-phases functionally graded sandwich plates, the work highlighted the significant roles played by individual material ingredients in influencing their frequencies.

Key Words
free vibration; functionally graded sandwich plates; higher-order shear deformation theory; natural frequencies; Navier's solution

Address
Pham Van Vinh: Department of Solid Mechanics, Le Quy Don Technical University, Hanoi, Viet Nam
Le Quang Huy: Institute of Techniques for Special Engineering, Le Quy Don Technical University, Hanoi, Viet Nam
Abdelouahed Tounsi: 1) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia, 2) Interdisciplinary Research Center for Construction and Building Materials, KFUPM, 31261 Dhahran, Saudi Arabia, 3) YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea, 4) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria

Abstract
Under constant and cyclic axial compression, square composite short columns reinforced with Self Compacting Concrete (SCC) added with scrap rubber infilled inside steel tubes and with different types of concrete were cast and tested. The test is carried out to find the effectiveness of utilizing an aggregate manufactured from industrial waste and to address the problems associated with the need for alternative reinforcements along with waste management. The main testing parameters are the type of concrete, the effect of fiber inclusion, and the significance of rubber-infilled steel tubes. The failure modes of the columns and axial load-displacement curves of the steel tube-reinforced columns were all thoroughly investigated. According to the test results, all specimens failed due to compression failure with a longitudinal crack along the loading axis. The fiber-reinforced column specimens demonstrated improved ductility and energy absorption. In comparison to the normal-weight concrete columns, the lightweight concrete columns significantly improved the axial load-carrying capacity. The addition of basalt fiber to the columns significantly increased the yield stress and ultimate stress to 9.21%. The corresponding displacement at yield load and ultimate load was reduced to 10.36% and 28.79%, respectively. The precision of volumetric information regarding the obtained crack quantification, aggregates, and the fiber in concrete is studied in detail through image processing using MATLAB environment.

Key Words
axial deformation; ductility; energy absorption; image processing; infilled steel tube column; squash load

Address
N.Divyah: Department of Civil Engineering, PSG Institute of Technology and Applied Research, Coimbatore, 641 062 Tamilnadu, India
R.Prakash: Department of Civil Engineering, Government College of Engineering, Tirunelveli 627007, India
S.Srividhya: Department of Civil Engineering, Builders Engineering College, Kangeyam, Tirupur 638108, India

Abstract
The present study introduces an optimum performance soft computing model for predicting the compressive strength of high-performance concrete (HPC) by comparing models based on conventional (kernel-based, covariance function-based, and tree-based), advanced machine (least square support vector machine-LSSVM and minimax probability machine regressorMPMR), and deep (artificial neural network-ANN) learning approaches using a common database for the first time. A compressive strength database, having results of 1030 concrete samples, has been compiled from the literature and preprocessed. For the purpose of training, testing, and validation of soft computing models, 803, 101, and 101 data points have been selected arbitrarily from preprocessed data points, i.e., 1005. Thirteen performance metrics, including three new metrics, i.e., a20-index, index of agreement, and index of scatter, have been implemented for each model. The performance comparison reveals that the SVM (kernel-based), ET (tree-based), MPMR (advanced), and ANN (deep) models have achieved higher performance in predicting the compressive strength of HPC. From the overall analysis of performance, accuracy, Taylor plot, accuracy metric, regression error characteristics curve, Anderson-Darling, Wilcoxon, Uncertainty, and reliability, it has been observed that model CS4 based on the ensemble tree has been recognized as an optimum performance model with higher performance, i.e., a correlation coefficient of 0.9352, root mean square error of 5.76 MPa, and mean absolute error of 4.1069 MPa. The present study also reveals that multicollinearity affects the prediction accuracy of Gaussian process regression, decision tree, multilinear regression, and adaptive boosting regressor models, novel research in compressive strength prediction of HPC. The cosine sensitivity analysis reveals that the prediction of compressive strength of HPC is highly affected by cement content, fine aggregate, coarse aggregate, and water content.

Key Words
compressive strength; hypothesis testing; machine learning models; multicollinearity

Address
Chukwuemeka Daniel: Pan African University Institute of Basic Sciences Technology and Innovation, Hosted atJomo Kenyatta University of Agriculture and Technology, Kenya
Jitendra Khatti and Kamaldeep Singh Grover: Department of Civil Engineering, Rajasthan Technical University, Kota, Rajasthan, India

Abstract
Waste foundry sand (WFS) is the waste product that cause environmental hazards. WFS can be used as a partial replacement of cement or fine aggregates in concrete. A database comprising 234 compressive strength tests of concrete fabricated with WFS is used. To construct the machine learning-based prediction models, the water-to-cement ratio, WFS replacement percentage, WFS-to-cement content ratio, and fineness modulus of WFS were considered as the model's inputs, and the compressive strength of concrete is set as the model's output. A base extreme gradient boosting (XGBoost) model together with two hybrid XGBoost models mixed with the tunicate swarm algorithm (TSA) and the salp swarm algorithm (SSA) were applied. The role of TSA and SSA is to identify the optimum values of XGBoost hyperparameters to obtain the higher performance. The results of these hybrid techniques were compared with the results of the base XGBoost model in order to investigate and justify the implementation of optimisation algorithms. The results showed that the hybrid XGBoost models are faster and more accurate compared to the base XGBoost technique. The XGBoost-SSA model shows superior performance compared to previously published works in the literature, offering a reduced system error rate. Although the WFS-to-cement ratio is significant, the WFS replacement percentage has a smaller influence on the compressive strength of concrete. To improve the compressive strength of concrete fabricated with WFS, the simultaneous consideration of the water-to-cement ratio and fineness modulus of WFS is recommended.

Key Words
compressive strength of concrete; extreme gradient boosting; green concrete; optimisation algorithms; waste foundry sand

Address
Danial Jahed Armaghani and Haleh Rasekh: School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
Panagiotis G. Asteris: Computational Mechanics Laboratory, School of Pedagogical and Technological Education, Heraklion, GR, 14121 Athens, Greece

Abstract
Beam-shaped components commonly rotate along a fixed axis when massive mechanical structures like rotors, jet engine blades, motor turbines, and rotating railway crossings perform their functions. For these structures to be useful in real life, their mechanical behavior is essential. Therefore, this is the first article to use the modified shear deformation theory type hyperbolic sine functions theory and the FEM to study the static bending response of rotating functionally graded GPL-reinforced composite (FG-GPLRC) beams with initial geometrical deficiencies in thermal media. Graphene platelets (GPLs) in three different configurations are woven into the beam's composition to increase its strength. By comparing the numerical results with those of previously published studies, we can assess the robustness of the theory and mechanical model employed in this study. Parameter studies are performed to determine the effect of various geometric and physical variables, such as rotation speed and temperature, on the bending reactions of structures.

Key Words
bending; elastic foundation; FG-GPLRC beam; finite element method; geometrical imperfection; rotational speed

Address
Bui Manh Cuong, Do Van Thom and Phung Van Minh: Faculty of Mechanical Engineering, Le Quy Don Technical University, Hanoi City, Vietnam
Abdelouahed Tounsi: 1) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia, 2) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Nguyen Thi Hai Van: Faculty of Industrial Education, The University of Danang-University of Technology and Education, 48 Cao Thang, Danang, Vietnam

Abstract
In this paper, the non-linear behavior of masonry-infill and bare steel frames using different beam-column connections under monotonic static loading was investigated through a parametric study. Numerical models were carried out using one- and two-dimensional modelling to validate the experimental results. After validating the experimental results by using these models, a parametric study was carried out to model the behavior of these frames using flushed, extended, and welded connections. The results showed that using the welded or extended connection is more efficient than using the flushed type in masonry-infilled steel frames, since the lateral capacities, initial stiffness, and toughness have been increased by 155%, 601%, and 165%, respectively in the case of using welded connections compared with those used in bare frames. The FE investigation was broadened to study the influence of the variation of the uniaxial column loads on the lateral capacities of the bare/infill steel frames. As the results showed when increasing the amount of uniaxial loading on the columns, whether in tension or compression, causes the lateral load capacity of the columns to decrease by 26% for welded infilled steel frames. Finally, the influence of using different types of beam-to-column connections on the vertical capacities of the bare/infill steel frames under settlement effect was also studied. As a result, it was found that, the vertical load capacity of all types of frames and with using any type of connections is severely reduced, and this decrease may reach 62% for welded infilled frames. Furthermore, the flushed masonry-infilled steel frame has a higher resistance to the vertical loads than the flushed bare steel frame by 133%.

Key Words
ABAQUS; bare frames; beam-to-column connections; column axial load level; masonry-infilled frames; SAP2000; settlement; steel frames

Address
Galal Elsamak: 1) Department of Civil Engineering, Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh, Egypt, 2) Department of Civil Engineering, Delta Higher Institute for Engineering and Technology, Mansoura, Egypt
Ahmed H. Elmasry and Basem O. Rageh: Department of Civil Engineering, Delta Higher Institute for Engineering and Technology, Mansoura, Egypt

Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2024 Techno-Press ALL RIGHTS RESERVED.
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Email: info@techno-press.com