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CONTENTS
Volume 91, Number 6, September25 2024
 

Abstract
In this paper, thermal buckling analysis was conducted using trigonometric shear deformation theory, which employs only four unknowns instead of five. This present theory is variationally consistent, and accounts for a trigonometric variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. The grading is provided along the thickness of the plate as per power law volume fraction variation of metal-matrix ceramic reinforced composite. The non-linear governing equation problem was solved for simply supported boundary conditions. Three types of thermal loads are assumed in this work: uniform, linear and non-linear distribution through-the-thickness. It is well known that material properties change with temperature variations and so the analysis was performed for both the cases: temperature-dependent (TD) and temperature-independent (TID) material properties. The impact on thermal buckling for both linear and non-linear temperature variation was considered. The results were validated for the TID case with other theories and were found to be in good agreement. Furthermore, a comprehensive analysis was performed to study the impact of grading indices and geometrical parameters, such as aspect ratio (a/b) and side-tothickness ratio (a/h), on the thermal buckling of the FG plate.

Key Words
functionally graded plate; stability equations; temperature dependent material properties; thermal buckling; trigonometric shear deformation theory

Address
Lazreg Hadji: Laboratory of Geomatics and Sustainable Development, University of Tiaret, Algeria; Department of Civil Engineering, University of Tiaret, Algeria
Royal Madan: Department of Mechanical Engineering, Grphic Era (Deemed to be University), Dehradun 248002, Uttarakhand, India
Hassen Ait Atmane: Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Hassiba Benbouali University of Chlef, Chlef, Algeria; Department of Civil Engineering, Hassiba Benbouali University of Chlef, Chlef, Algeria
Fabrice Bernard: Laboratory of Civil Engineering and Mechanical Engineering, INSA Rennes, University of Rennes, France
Nafissa Zouatnia: Department of Civil Engineering, University of Tiaret, Algeria
Abdelkader Safa: Department of Civil Engineering, University of Relizane, 48000, Algeria

Abstract
This study presents a methodical investigation into improving structural designs through the analytical examination of the dynamic behavior of functionally graded plates (FGPs) resting on viscoelastic foundations. By employing a four variable first-order shear deformation theory, the study computes non-dimensional frequencies for a variety of porous FGPs with diverse graded patterns and porosity distributions. Different gradient patterns of the plates are considered, and three distinct functions— sigmoid (S-FGM), exponential (E-FGM), and power-law (P-FGM)—are utilized to assess material performance in specific directions. The equations of motion are derived and solved using both Navier's method and Hamilton's principle. Analytical solutions for vibration frequency are provided to validate the proposed methodology against existing literature. Furthermore, a comprehensive parametric analysis is conducted, taking into account various factors such as ceramic material, porosity distribution, gradient index, length-to-thickness ratio, gradient pattern, and damping coefficient. The findings suggest that enhancing the damping coefficient of the viscoelastic foundation can significantly improve the free-vibrational response of functionally graded material plates.

Key Words
behavior; functionally graded plates; viscoelastic foundations

Address
Hafida Driz: Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria
Amina Attia: Department of Civil Engineering and Public Works, Engineering and Sustainable Development Laboratory,
Faculty of Science and Technology, University of Ain Temouchent, Algeria
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Farouk Yahia Addou: Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria; Civil Engineering Department, Faculty of Sciences and Technology, Abdelhamid Ibn Badis University, Mostaganem, Algeria
Mohamed Bourada: Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria
Abdeldjebbar Tounsi: Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria; Mechanical Engineering Department, Faculty of Science & Technology, University of Relizane, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology, University of Sidi Bel Abbes, Algeria; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Mohammed Balubaid: Department of Industrial Engineering, King Abdulaziz University, Jeddah, Saudi Arabia
S.R. Mahmoud: GRC Department, Applied College, King Abdulaziz University. Jeddah 21589, Saudi Arabia

Abstract
In this paper, an effort is made to present a detailed analysis of dynamic behavior of functionally graded carbon nanotube-reinforced pipes under the influence of an accelerating moving load. Again, the material properties of the nanocomposite pipe will be determined by following the rule of mixtures, considering a specific distribution and volume fraction of CNTs within the pipe. In the present study, temperature-dependent material properties have been considered. The Navier-Stokes equations are used to determine the radial force developed by the viscous fluid. The structural analysis has been carried out based on Reddy's higher-order shear deformation shell theory. The equations of motion are derived using Hamilton's principle. The resulting differential equations are solved using the Differential Quadrature and Integral Quadrature methods, while the dynamic responses are computed with the use of Newmark's time integration scheme. These are many parameters, ranging from those connected with boundary conditions to nanotube geometrical characteristics, velocity, and acceleration of the moving load, and, last but not least, volume fraction and distribution pattern of CNTs. The results indicate that any increase in the volume fraction of CNTs will lead to a decrease in the transient deflection of the structure. It is also observed that maximum displacement occurs with an increase in the load speed, slightly delayed compared to decelerating motion.

Key Words
DQ-IQ method, dynamic response, FG-CNT pipe, moving load, viscous fluid

Address
Ali Chen: Business School, Hunan University of Science and Technology, Xiangtan 411201, Hunan, China
Omidreza Masoudian: Department of Mechanical Engineering, University of Kashan, Kashan, Iran
Gholamreza Soleimani Jafari: Department of Mechanical Engineering, Kashan Branch, Islamic Azad University, Kashan, Iran

Abstract
Accurately predicting the strength of concrete is vital for ensuring the safety and durability of structures, thereby contributing to time and cost savings throughout the design and construction phases. The compressive strength of concrete is determined by various material factors, including the type of cement, composition ratios of concrete mixtures, curing time, and environmental conditions. While mix design establishes the proportions of each material for concrete, predicting strength before experimental measurement remains a challenging task. In this study, Abrams's law was chosen as a representative investigative approach to estimating concrete compressive strength. Abrams asserted that concrete compressive strength depends solely on the water-cement ratio and proposed a logarithmic linear relationship. However, Abrams's law is only applicable to concrete using cement as the sole binding material and may not be suitable for modern concrete mixtures. Therefore, this research aims to predict concrete compressive strength by applying various conventional regression analyses and machine learning methods. Six models were selected based on performance experiment data collected from various literature sources on different concrete mixtures. The models were assessed using Root Mean Squared Error (RMSE) and coefficient of determination (R2) to identify the optimal model.

Key Words
Abrams's law; compressive strength; concrete; machine learning; prediction model

Address
Sangwoo Kim, Jinsup Kim: Department of Civil Engineering, Gyeongsang National University, Jinju 52828, Republic of Korea
Jaeho Shin: Department of Information and Statistics, Gyeongsang National University, Jinju 52828, Republic of Korea
Youngsoon Kim: Department of Information and Statistics and Dept. of Bio & Medical Bigdata (BK21 Four Program), Gyeongsang National University, Jinju 52828, Republic of Korea

Abstract
This article proposes a new methodology for identifying beam damage based on changes in modal parameters using the Double Stage Extended Improved Particle Swarm Optimization (DSEIPSO) technique. A finite element code is first developed in MATLAB to model an ideal beam structure based on classical beam theory. An experimental study is then performed on a laboratory-scale beam, and the modal parameters are extracted. An improved version of the PSO algorithm is employed to update the finite element model based on the experimental measurements, representing the real structure and forming the baseline model for all further damage detection. Subsequently, structural damages are introduced in the experimental beam. The DSEIPSO algorithm is then utilized to optimize the objective function, formulated using the obtained mode shapes and the natural frequencies from the damaged and undamaged beams to identify the exact location and extent of the damage. Experimentally obtained results from a simple cantilever beam are used to validate the effectiveness of the proposed method. The illustrated results show the effectiveness of the proposed method for structural damage detection in the SHM field.

Key Words
cantilever beam; damage detection; double stage extended improved particle swarm optimization; dynamic condensation; finite element; modal analysis

Address
Thakurdas Goswami and Partha Bhattacharya: Department of Civil Engineering, Jadavpur University, India

Abstract
This study explores the use of advanced concrete types to improve the performance of composite steel shear walls (CSPSWs), particularly in delaying cracking and failure. A two-phase approach is implemented. Phase I utilizes non-linear finite element analysis and Gene Expression Programming to develop a novel method for determining the minimum concrete thickness required in CSPSWs. Phase II investigates the effect of concrete type, opening area, and location on the behavior of CSPSWs with openings. The results demonstrate that ultra-high performance concrete (UHPFRC) significantly reduces out-ofplane displacement and tensile cracking compared to normal concrete. Additionally, the study reveals a strong correlation between opening position and load-bearing capacity, with position L3 exhibiting the greatest reduction as opening size increases. Finally, UHPFRC's superior energy dissipation translates to a higher equivalent viscous damping coefficient.

Key Words
composite steel plate shear wall; concrete panel thickness; finite element analysis; out-of-plane deformation; UHPFRC

Address
Mehdi Ebadi-Jamkhaneh: Department of Civil Engineering, School of Engineering, Damghan University, Damghan, Iran

Abstract
In the present work, the deformation and stresses induced in a functionally graded disk have been reported for different loading conditions. The governing differential equation is solved using the classical method namely Navier's method by considering thermal and mechanical boundary conditions at the surface of the disk. To simplify solving the second-order differential equation, a plane stress condition was assumed. Following validation using a one-dimensional steady-state heat condition problem, temperature variations were computed for constant heat generation and varying conductivity. The research aims to investigate both the individual and combined effects of rotation, gravity, and temperature with constant heat generation on a hollow disk operating under complex loading conditions. The results demonstrated a high degree of accuracy when compared with those in existing literature. Material properties, such as Young's modulus, density, conductivity, and thermal expansion coefficient, were modeled using a power law variation along the disk's radius by considering aluminum as a base material. The proposed analytical method is straightforward, providing valuable insights into the behavior of disks under various loading conditions. This method is particularly useful for researchers and industries in selecting appropriate loading conditions and grading parameters for engineering applications, including aerospace components, energy systems, and rotary machinery parts.

Key Words
classical method; constant heat generation; elastic analysis; functionally graded disk; variable conductivity

Address
Sanjay Kumar Singh: Department of Mechanical Engineering, Chhatrapati Shivaji Institute of Technology Durg, Chhattisgarh 491001, India
Lakshman Sondhi: Department of Mechanical Engineering, Shri Shankaracharya Technical Campus Bhilai, Chhattisgarh 490020, India
Rakesh Kumar Sahu: Department of Mechanical Engineering, Visvesvaraya National Institute of Technology, Nagpur, Maharashtra 440010, India
Royal Madan: Department of Mechanical Engineering, Graphic Era (Deemed to be University), Dehradun 248002, Uttarakhand, India
Sanjay Yadav: Department of Mechanical Engineering, I.T.S Engineering College, 46, Knowledge Park-III, Greater Noida, U.P.-201310, India

Abstract
The prediction of the moment rotation behavior of semi-rigid connections has been the subject of extensive research. However, to improve the accuracy of these predictions, there is a growing interest in employing machine learning algorithms. This paper investigates the effectiveness of using Multi-gene genetic programming (MGGP) to predict the moment-rotation behavior of flush-end plate connections compared to that of artificial neural networks (ANN) and previous studies. It aims to automate the process of determining the most suitable equations to accurately describe the behavior of these types of connections. Experimental data was used to train ANN and MGGP. The performance of the models was assessed by comparing the values of coefficient of determination (R2), maximum absolute error (MAE), and root-mean-square error (RMSE). The results showed that MGGP produced more accurate, reliable, and general predictions compared to ANN and previous studies with an R2 exceeding 0.99, an RMSE of 6.97, and an MAE of 38.68, highlighting its advantages over other models. The use of MGGP can lead to better modeling and more precise predictions in structural design. Additionally, an experimentally-based regression analysis was conducted to obtain the rotational capacity of FECs. A new equation was proposed and compared to previous ones, showing significant improvement in accuracy with an R2 score of 0.738, an RMSE of 0.014, and an MAE of 0.024.

Key Words
artificial neural network; flush end plate; moment-rotation; multi-gene genetic programming; semi-rigid connections

Address
Amirmohammad Rabbani: School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran
Amir Reza Ghiami Azad: School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran
Hossein Rahami: School of Engineering Science, College of Engineering, University of Tehran, Tehran, Iran

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