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CONTENTS
Volume 32, Number 4, October 2023
 

Abstract
Reducing the self-weight of reinforced concrete structures problem is discussed in this paper by using two types of self-weight reduction, the first is by using lightweight coarse aggregate (crushed brick) and the second is by using styropor block. Experimental and Numerical studies are conducted on (LWAC) lightweight aggregate reinforced concrete slabs, having styropor blocks with various sizes of blocks and the ratio of shear span to the effective depth (a/d). The experimental part included testing eleven lightweight concrete one-way simply supported slabs, comprising three as reference slabs (solid slabs) and eight as styropor block slabs (SBS) with a total reduction in cross-sectional area of (43.3% and 49.7%) were considered. The holes were formed by placing styropor at the ineffective concrete zones in resisting the tensile stresses. The length, width, and thickness of specimen dimensions were 1.1 m, 0.6 m, and 0.12 m respectively, except one specimen had a depth of 85 mm (which has a cross-sectional area equal to styropor block slab with a weight reduction of 49.7%). Two shear spans to effective depth ratios (a/d) of (3.125) for load case (A) and (a/d) of (2) for load case (B), (two-line monotonic loads) are considered. The test results showed under loading cases A and B (using minimum shear reinforcement and the reduction in cross-sectional area of styropor block slab by 29.1%) caused an increase in strength capacity by 60.4% and 54.6 % compared to the lightweight reference slab. Also, the best percentage of reduction in cross-sectional area is found to be 49.7%. Numerically, the computer program named (ANSYS) was used to study the behavior of these reinforced concrete slabs by using the finite element method. The results show acceptable agreement with the experimental test results. The average difference between experimental and numerical results is found to be (11.06%) in ultimate strength and (5.33%) in ultimate deflection.

Key Words
lightweight aggregate concrete; monotonic load; one-way slab; structural behavior; styropor block

Address
Department of Civil Engineering, College of Engineering, Al-Nahrain University, Jadriya, Baghdad, Iraq

Abstract
On the basis of Flügge shell theory, the vibrations of single walled carbon nanotubes (SWCNTs) are investigated. The structure of armchair single walled carbon nanotubes are used here. Influences of length-to-diameter ratios and the two boundary conditions on the natural frequencies of armchair SWCNTs are examined. The Rayleigh-Ritz method is employed to determine eigen frequencies for single walled carbon nanotubes. The solution is obtained using the geometric characteristics and boundary conditions for natural frequencies of SWCNTs. The natural frequencies decrease as ratio of length to diameter increase and the effect of frequencies is less significant and more prominent for long tube. To assess the frequency confirmation carried out in this paper are compared with the earlier computations.

Key Words
armchair SWCNTs; boundary conditions; Flügge shell theory; length-to-diameter ratios; Rayleigh-Ritz method

Address
Mohamed A. Khadimallah: Department of Civil Engineering, College of Engineering in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj, 11942, Saudi Arabia
Imene Harbaoui: Laboratory of Applied Mechanics and Engineering LR-MAI, University Tunis El Manar- -ENIT BP37- Le belvédère, 1002, Tunisia
Sofiene Helaili: (1) Carthage University, Tunisia Polytechnic School, LASMAP (LR03ES06), La Marsa, Tunisia, (2) Carthage University, ISTEUB, Tunis, Tunisia
Abdelhakim Benslimane: Laboratoire de Mécanique Matériaux et Énergétique (L2ME), Département Génie Mécanique, Faculté de Technologie, Université de Bejaia, 06000 Bejaia, Algérie
Humaira Sharif, Muzamal Hussain and Muhammad Nawaz Naeem: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Mohamed R. Ali: (1) Faculty of Engineering and Technology, Future University in Egypt New Cairo 11835, Egypt, (2) Basic Engineering Science Department, Benha Faculty of Engineering, Benha University, Benha, Egypt
Aqib Majeed: Department of Mathematics, The University of Faisalabad, Sargodha Road, University Town Faisalabad, 38000, Pakistan
Abdelouahed Tounsi: (1) YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea, (2) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia


Abstract
Fly ash, granulated blast furnace slag, marble waste powder, etc. are just some of the by-products of other sectors that the construction industry is looking to include into the many types of concrete they produce. This research seeks to use surrogate machine learning methods to forecast the compressive strength of self-compacting concrete. The surrogate models were developed using Gradient Boosting Machine (GBM), Support Vector Machine (SVM), Random Forest (RF), and Gaussian Process Regression (GPR) techniques. Compressive strength is used as the output variable, with nano silica content, cement content, coarse aggregate content, fine aggregate content, superplasticizer, curing duration, and water-binder ratio as input variables. Of the four models, GBM had the highest accuracy in determining the compressive strength of SCC. The concrete's compressive strength is worst predicted by GPR. Compressive strength of SCC with nano silica is found to be most affected by curing time and least by fine aggregate.

Key Words
compressive strength; IoT; self-compacting concrete; sensitivity; surrogate machine learning

Address
Neeraj Kumar Shukla, Mohamed Abbas, Hany S. Hussein and Rajesh Verma: Electrical Engineering Department, College of Engineering, King Khalid University, Abha 61421, Kingdom of Saudi Arabia
Aman Garg and Mona Aggarwal: Department of Multidisciplinary Engineering, The NorthCap University, Gurugram, Haryana, India - 122017
T.M. Yunus Khan: Mechanical Engineering Department, College of Engineering, King Khalid University, Abha 61421, Kingdom of Saudi Arabia

Abstract
The mechanical properties of Recycled Aggregate Concrete (RAC) with 100 percent Recycled Coarse Aggregate (RCA) under loading rates were investigated in depth. The theoretical model was validated utilizing the RAC elastic modulus obtained from cylindrical specimens subjected to various strain rates. Viscoelastic theories have traditionally been used to describe creep and relaxation of viscoelastic materials at low strain rates. In this study, viscoelastic theories were extended to the time domain of high strain rates. The theory proposed was known as reversed viscoelastic theory. Normalized Dirichlet-Prony theory was used as an illustration, and its parameters were determined. Comparing the predicted results to the experimental data revealed a high level of concordance. This methodology demonstrated its ability to characterize the strain rate effect for viscoelastic materials, as well as its applicability for determining not only the elastic modulus for viscoelastic materials, but also their shear and bulk moduli.

Key Words
elastic modulus; normalized Dirichlet-Prony; recycled aggregate concrete; shear and bulk moduli; strain rates; viscoelastic

Address
Suthee Piyaphipat, Boonchai Phungpaingam and Kamtornkiat Musiket: Department of Civil Engineering, Rajamangala University of Technology Thunyaburi, Pathumthani, Thailand
Yunping Xi: Department of Civil and Architectural Engineering, University of Colorado, Boulder, Colorado, USA

Abstract
This paper provides the free vibrations of chiral carbon nanotubes. The governing equations of Flügge theory is considered for vibration frequencies of chiral single walled carbon nanotubes. The solution of frequency equation is obtained from a novel model for better representation of stubby and short vibration characteristics of chiral tubes with clamped-clamped and clamped-simply supported end conditions. For the harmonic response of this tube, the model displacement function is adopted. The variational approach Rayleigh-Ritz method with kinetic and strain energies are used. The Lagragian function is differentiated with respect to unknown functions. The frequency equation is written in compact form to solve with MATLAB software. The frequencies of chiral SWCNTs for first ten aspect ratios as small level are investigated. The results shown as for decreasing the aspect rations, the frequencies are increases. The presented results of this model are verified with experimental and numerical results, which found as an excellent agreement.

Key Words
boundary conditions; chiral SWCNTs; Flügge shell theory; length-to-diameter ratios; Rayleigh-Ritz method

Address
Muzamal Hussain, Humaira Sharif and Muhammad Nawaz Naeem: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Mohamed R. Ali: (1) Faculty of Engineering and Technology, Future University in Egypt New Cairo 11835, Egypt, (2) Basic Engineering Science Department, Benha Faculty of Engineering, Benha University, Benha, Egypt
Abdelhakim Benslimane: Laboratoire de Mécanique Matériaux et Énergétique (L2ME), Département Génie Mécanique, Faculté de Technologie, Université de Bejaia, 06000 Bejaia, Algérie
Mohamed A. Khadimallah: Department of Civil Engineering, College of Engineering in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj, 11942, Saudi Arabia
Imene Harbaoui: Department of Chemical Engineering, College of Engineering, King Khalid University, Abha 61411, Kingdom of Saudi Arabia
Sofiene Helaili: (1) Carthage University, Tunisia Polytechnic School, LASMAP (LR03ES06), La Marsa, Tunisia, (2) Carthage University, ISTEUB, Tunis, Tunisia
Aqib Majeed: Department of Mathematics, The University of Faisalabad, Sargodha Road, University Town Faisalabad, 38000, Pakistan
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, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
This study proposes a novel use of backpropagated Levenberg-Marquardt neural networks based on computational intelligence heuristics to comprehend the examination of hybrid nanoparticles on the flow of dusty liquid via stretched cylinder. A two-phase model is employed in the present work to describe the fluid flow. The use of desulphated nanoparticles of silver and molybdenum suspended in water as base fluid. The mathematical model represented in terms of partial differential equations, Implementing similarity transformationsis model is converted to ordinary differential equations for the analysis . By adjusting the particle mass concentration and curvature parameter, a unique technique is utilized to generate a dataset for the proposed Levenberg-Marquardt neural networks in various nanoparticle circumstances on the flow of dusty liquid via stretched cylinder. The intelligent solver Levenberg-Marquardt neural networks is trained, tested and verified to identify the nanoparticles on the flow of dusty liquid solution for various situations. The Levenberg-Marquardt neural networks approach is applied for the solution of the hybrid nanoparticles on the flow of dusty liquid via stretched cylinder model. It is validated by comparison with the standard solution, regression analysis, histograms, and absolute error analysis. Strong agreement between proposed results and reference solutions as well as accuracy provide an evidence of the framework's validity.

Key Words
artificial neural networks; brownian motion; mathematical model; nanoparticles; temperature gradient

Address
Tayyab Zamir and Farooq Ahmed Shah: Department of Mathematics, COMSATS University Islamabad, Attock Campus, Pakistan
Muhammad Shoaib: (1) Department of Mathematics, COMSATS University Islamabad, Attock Campus, Pakistan, (2) Yuan Ze University, AI Center, Taoyuan 320, Taiwan
Atta Ullah: (1) Department of Mathematics, COMSATS University Islamabad, Attock Campus, Pakistan, (2) Quaid-i-Azam University, Islamabad

Abstract
The rapid development of road transport has increased the number of bridges that require widening. A critical issue in the construction of bridge widening is the influence of vibrations of the old bridge on the casting of wet joint concrete between the old and new bridges owing to the running traffic. Typically, the bridge is closed to traffic during the pouring of wet joint concrete, which negatively affects the existing transportation network. In this study, a newly developed microscopic traffic load modeling approach and the vehicle-bridge interaction theory are incorporated to develop a refined numerical framework for the analysis of random traffic-bridge coupled dynamics. This framework was used to investigate traffic-induced vibrations at the wet joint of a widened bridge. Based on an experimental study on the vibration resistance of wet joint concrete, traffic control strategies were proposed to ensure the construction performance of cast-in-site wet joint concrete under random traffic without interruption. The results show that the vibration displacement and frequency of the old bridge, estimated by the proposed framework, were comparable with those obtained from field measurements. Based on the target peak particle velocity and vibration amplitude of the wet joint concrete, it was found that traffic control measures, such as limiting vehicle gross weight and limiting traffic volume by closing an additional traffic lane, could ensure the construction performance of the wet joint concrete.

Key Words
concrete bridge; traffic control; UHPC; VBI; vibration; wet joint; widening

Address
Junyong Zhou, Zunian Zhou and Liwen Zhang: School of Civil Engineering, Guangzhou University, Guangzhou 510006, China
Junping Zhang: Earthquake Engineering Research & Test Center, Guangzhou University, Guangzhou 510006, China
Xuefei Shi: Department of Bridge Engineering, College of Civil Engineering, Tongji University, Shanghai 200092, China

Abstract
In this article, the performance of steel fiber-reinforced concrete (SFRC) flat slabs was investigated numerically. The influence of flexural steel reinforcement, steel fiber content, concrete compressive strength, and slab thickness were discussed. The numerical model was developed using ATENA-Gid, user-friendly software for non-linear structural analysis for the evaluation and design of reinforced concrete elements. The numerical model was calibrated based on eight experimental tests selected from the literature to validate the actual behavior of steel fiber in the numerical analysis. Then, a parametric study of 144 specimens was generated and discussed the impact of various parameters on the punching shear strength, and statistical analysis was carried out. The results showed that slab thickness, steel fiber content, and concrete compressive strength positively affect the punching shear capacity. The fib Model Code 2010 for specimens without steel fibers and the model of Muttoni and Ruiz for SFRC specimens presented a good agreement with the results of this study.

Key Words
ATENA-Gid; flat slab; punching shear; steel-fiber reinforced concrete

Address
Baraa J.M. AL-Eliwi: Department of Civil Engineering, College of Engineering, University of Mosul, 41001 Mosul, Iraq
Mohammed S. Al Jawahery: Highways and Bridges Engineering Department, Technical College of Engineering, Duhok Polytechnic University, Duhok, Iraq

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