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CONTENTS
Volume 45, Number 6, December25 2022
 


Abstract
In this study, a new type of energy absorbers with a functionally graded thickness is investigated, these type of absorbers absorb energy through expanding-folding processes. The expanding-folding absorbers are composed of two sections: a thin-walled aluminum matrix and a thin-walled steel mandrel. Previous studies have shown higher efficiency of the mentioned absorbers compared to the conventional ones. In this study, the effect of thickness which has been functionally-graded on the aluminum matrix (in which expansion occurs) was investigated. To this end, initial functions were considered for the matrix thickness, which was ascending/descending along the axis. The study was done experimentally and numerically. Comparing the experimental data with the numerical results showed high consistency between the numerical and experimental results. In the final section of this study, the best energy absorber functionally graded thickness was introduced by optimization using a thirdorder genetic algorithm. The optimization results showed that by choosing a minimum thickness of 1.6 mm and the exponential coefficient of 3.25, the most optimal condition can be obtained for descending thickness absorbers.

Key Words
crashworthiness; energy absorber; genetic algorithm; multi-objective optimization

Address
Chunwei Zhang:1)Multidisciplinary Centre for Infrastructure Engineering, Shenyang University of Technology, Shenyang, 110870, China
2)Structural Vibration Control Group, Qingdao University of Technology, Qingdao 266033, China

Limeng Zhu:Structural Vibration Control Group, Qingdao University of Technology, Qingdao 266033, China

Farayi Musharavati:Department of Mechanical and Industrial Engineering, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar

Afrasyab Khan:Institute of Engineering and Technology, Department of Hydraulics and Hydraulic and Pneumatic Systems, South Ural State
University, Lenin Prospect 76, Chelyabinsk, 454080, Russian Federation

Tamer A. Sebaey:1)Engineering Management Department, College of Engineering, Prince Sultan University, Riyadh, Saudi Arabia
2)Mechanical Design and Production Department, Faculty of Engineering, Zagazig University,
P.O. Box 44519, Zagazig, Sharkia, Egypt

Abstract
Steel–precast ultra-high-performance concrete (UHPC) composite beams with demountable high-strength frictiongrip bolt (HSFGB) shear connectors can be used for accelerated bridge construction (ABC) and achieve excellent structural performance, which is expected to be dismantled and recycled at the end of the service life. However, no investigation focuses on the demountability and reusability of such composite beams, as well as the installation difficulties during construction. To address this issue, this study conducted twelve push-out tests to investigate the effects of assembly condition, bolt grade, bolt– hole clearance, infilling grout and pretension on the crack pattern, failure mode, load–slip/uplift relationship, and the structural performance in terms of ultimate shear strength, friction resistance, shear stiffness and slip capacity. The experimental results demonstrated that the presented composite beams exhibited favorable demountability and reusability, in which no significant reduction in strength (less than 3%) and stiffness (less than 5%), but a slight improvement in ductility was observed for the reassembled specimens. Employing oversized preformed holes could ease the fabrication and installation process, yet led to a considerable degradation in both strength and stiffness. With filling the oversized holes with grout, an effective enhancement of the strength and stiffness can be achieved, while causing a difficulty in the demounting of shear connectors. On the basis of the experimental results, more accurate formulations, which considered the effect of bolt–hole clearance, were proposed to predict the shear strength as well as the load–slip relationship of HSFGBs in steel–precast UHPC composite beams.

Key Words
demountable; high-strength friction-grip bolt; push-out test; shear connector; steel–UHPC composite beam

Address
Haibo Jiang, Haozhen Fang, Jinpeng Wu and Gongfa Chen:School of Civil and Transportation Engineering, Guangdong Univ. of Technology,
Guangzhou Higher Education Mega Center, Guangzhou, 510006, China

Zhuangcheng Fang and Shu Fang:1)School of Civil and Transportation Engineering, Guangdong Univ. of Technology,
Guangzhou Higher Education Mega Center, Guangzhou, 510006, China
2)Earthquake Engineering Research & Test Center, Guangzhou University,
Guangzhou Higher Education Mega Center, Guangzhou, 510006, China

Abstract
This paper presented an experimental study of the bond-slip behavior of reactive powder concrete (RPC)-filled square steel tube. A total of 18 short composite specimens were designed forstatic push-out test, and information on their failure patterns, load-slip behavior and bond strength was presented. The effects of width-to-thickness ratio, height-to-width ratio and the compressive strength of RPC on the bond behavior were discussed. The experimental results show that:(1) the push-out specimens remain intact and no visible local buckling appears on the steel tube, and the interfacial scratches are even more pronounced at the internal steel tube of loading end; (2) the bond load-slip curves with different width-to-thickness ratios can be divided into two types, and the main difference is whether the curves have a drop in load with increasing slip; (3) the bond strength decreases with the increase of the width-to-thickness ratio and height-width ratio, while the influence of RPC strength is not consistent; (4) the slippage has no definite correlation with bond strength and the influence of designed parameters on slippage is not evident. On the basis of the above analysis, the expressions of interface friction stress and mechanical interaction stress are determined by neglecting chemical adhesive force, and the calculation model of bond strength for RPC filled in square steel tube specimens is proposed. The theoretical results agree well with the experimental data.

Key Words
bond behavior; interface bond strength; push-out test; reactive powder concrete (RPC); square steel tube

Address
Qiuwei Wang:1)College of Civil Engineering, Xi'an University of Architecture & Technology, No. 13 Yanta Road, Xi'an, P. R. China
2)Key Lab of Structural Engineering and Earthquake Resistance, Ministry of Education (XAUAT),
No. 13 Yanta Road, Xi'an, P. R. China

Hang Zhao:College of Civil Engineering, Xi'an University of Architecture & Technology, No. 13 Yanta Road, Xi'an, P. R. China

Abstract
Numerical investigation on dynamic characteristics of sandwich plates under periodic and thermal loads has been presented by assuming that the plate has three layers which are a foam core and two skins. The foam core made of Aluminum has porosities with uniform and graded dispersions. The sandwich plate has been supposed to be affected by periodical compressive loads. Also, temperature variation causes uniform thermal load. The formulation has been established based upon a higher-order plate theory and Ritz method has been used to solve the equations of motion. The stability boundaries have also been obtained performing Bolotin's method. It will be indicated that stability boundaries of the sandwich plate depend on periodical load parameters, porosities,skin thickness and temperature.

Key Words
advanced thermal analysis; dynamics; heat; numerical; plate theory; sandwich plate

Address
Mouayed H.Z. Al-Toki:Middle Technical University, Technical College, Baghdad, Iraq

Wael Najm Abdullah, Ridha A. Ahmed, Nadhim M. Faleh and Raad M. Fenjan:Al-Mustansiriah University, Engineering Collage P.O. Box 46049, Bab-Muadum, Baghdad 10001, Iraq


Abstract
This paper presents an analytical solution to study the combined effect of non-local and stretching effect on the vibration of advanced functionally graded (FG) nanoplates. A new quasi-3D plate theory is presented; there are only five unknowns and any shear correction factor is used. A new displacement field with a new shear warping function is proposed. The equilibrium equations of the FG nanoplates are obtained using the Hamilton principle and solved numerically using the Navier technique. The material properties of functionally graded nanoplates are presumed to change according to the power-law distribution of ceramic and metal constituents. The numerical results of this work are compared with those of other published results to indicate the accuracy and convergence of this theory. Hence, a profound parameterstudy is also performed to show the influence of many parameters of the functionally graded nanoplates on the free vibration responses is investigated.

Key Words
free vibration; functionally graded material; nanoplates; Quasi-3D nonlocal elasticity theory

Address
Smain Bezzina:Deanship for Scientific research, King Abdulaziz University, Jeddah 21589, Saudi Arabia

Aicha Bessaim and 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, Mascara, Algérie

Marc Azab:College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait

Abstract
This research deals with the study of the Thomson heating effect in magneto-thermoelastic homogeneous isotropic rotating medium, influenced by linearly distributed load and as a result of modified couple stress theory. The charge density is taken as a function of the time of the induced electric current. The heat conduction equation with energy dissipation and with hyperbolic two-temperature (H2T) is used to formulate the model of the problem. Laplace and Fourier transforms are used to solve this mathematical model. Various components of displacement, temperature change, and axial stress as well as couple stress are obtained from the transformed domain. To get the solution in physical domain, numerical inversion techniques have been employed. The Thomson effect with GN (Green-Nagdhi) -III theory and Modified Couple Stress Theory (MCST) is shown graphically on the physical quantities.

Key Words
hyperbolic two temperature; length scale parameters; modified couple stress theory; Thomson effect

Address
Iqbal Kaur:Department of Mathematics, Government College for Girls, Palwal, Kurukshetra, Haryana, India

Kulvinder Singh:Faculty of Engineering, UIET, Kurukshetra University Kurukshetra, Haryana, India

Abstract
The slit members have lower strength and lower stiffness, which might lead to lower energy dissipation. In order to improve the seismic performance of the slit members, the paper proposes the shear lead damper, which has stable performance and small deformation energy dissipation capacity. Therefore, the shear lead damper can set in the vertical silts of the slit member to transmit the shear force and improve energy dissipation, which is suitable for the slit member. Initially, the symmetrical teeth-shaped lead damper was tested and analyzed. Then the staggered teeth-shaped lead dampers were developed and analyzed, based on the defect analysis and build improvements of the symmetrical specimen. Based on the parameter analysis, the main influence factors of hysteretic performance are the internal teeth, the steel baffles, and the width and length of damper. Finally, the theoretical analysis was presented on the hysteretic curve. And the skeleton curve and hysteresis path were identified. Based on the above theoretical analysis, the design method was proposed, including the damping force, the hysteresis model and the design recommendations.

Key Words
shear lead damper; energy dissipation; hysteresis performance; theoretical analysis; design method

Address
Chong Rong, Wenkai Tian, Peng Wang and Qingxuan Shi:1)College of Civil Engineering, Xi'an University of Architecture & Technology, Xi'an 710055, China
2)Key Laboratory of Structural Engineering and Seismic Resistance Education,
Xi'an University of Architectural & Technology, Xi

Abstract
Geopolymer concrete (𝐺𝑃𝐶) has emerged as a feasible choice for construction materials as a result of the environmental issues associated with the production of cement. The findings of this study contribute to the development of machine learning methods for estimating the properties of eco-friendly concrete to help reduce 𝐶𝑂2 emissions in the construction industry. The compressive strength (𝑓𝑐) of 𝐺𝑃𝐶 is predicted using artificial intelligence approaches in the present study when ground granulated blast-furnace slag (𝐺𝐺𝐵𝑆) is substituted with natural zeolite (𝑁𝑍), silica fume (𝑆𝐹), and varying 𝑁𝑎𝑂𝐻 concentrations. For this purpose, two machine learning methods multi-layer perceptron (𝑀𝐿𝑃) and radial basis function (𝑅𝐵𝐹) were considered and hybridized with arithmetic optimization algorithm (𝐴𝑂𝐴), and grey wolf optimization algorithm (𝐺𝑊𝑂). According to the results, all methods performed very well in predicting the 𝑓𝑐 of 𝐺𝑃𝐶. The proposed 𝐴𝑂𝐴 − 𝑀𝐿𝑃 might be identified as the outperformed framework, although other methodologies (𝐴𝑂𝐴 − 𝑅𝐵𝐹, 𝐺𝑊𝑂 − 𝑅𝐵𝐹, and 𝐺𝑊𝑂 − 𝑀𝐿𝑃) were also reliable in the 𝑓𝑐 of 𝐺𝑃𝐶 forecasting process.

Key Words
artificial intelligence; compressive strength; eco-friendly concrete; geopolymer concrete; optimization algorithms; prediction

Address
Xiang Yang:School of Civil Engineering, Chongqing Vocational Institute of Engineering, Chongqing 402260, China

Jiang Daibo:Logistics Base, Chongqing Technology and Business Institute, Chongqing401520, China

Hateo Gou:Building Department of Shandong University, Jinan, 250000, China

Abstract
Composite flooring systems consisting of cold-formed steel joists and reinforced concrete slabs offer an efficient, lightweight solution. However, utilisation of composite action to achieve enhanced strength and economical design has been limited. In this study, finite element modelling was utilised to create a three-dimensional model which was then validated against experimental results for a composite flooring system consisting of cold-formed steel joists, reinforced concrete slab and steel bolt shear connectors. This validated numerical model was then utilised to perform parametric studies on the performance of the structural system. The results from the parametric study demonstrate that increased thickness of the concrete slab and increased thickness of the cold formed steel beam resulted in higher moment capacity and stiffness of the composite flooring system. In addition, reducing the spacing of bolts and spacing of the cold formed steel beams both resulted in enhanced load capacity of the composite system. Increasing the concrete grade was also found to increase the moment capacity of the composite flooring system. Overall, the results show that an efficient, lightweight composite flooring system can be achieved and optimised by selecting suitable concrete slab thickness, cold formed beam thickness, bolt spacing, cold formed beam spacing and concrete grade.

Key Words
cold-formed steel beams; composite action; flexural behaviour; composite cold-formed steel and reinforced concrete; flooring systems; composite floors; finite element method

Address
Omar A. Shamayleh and Harry Far:School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology,
University of Technology Sydney (UTS), Sydney, Australia

Abstract
Compression experiments were conducted to investigate the compressive behavior of built-up open-section columns consisting of four cold-formed steel channels (BOCCFSs) of different lengths, thicknesses, and cross-section sizes (OB90 and OB140). The load-displacement curves, failure modes, and maximum compression strength values were analyzed in detail. The tests showed that the failure modes of the OB90 specimens transformed from a large deformation concentration induced by local buckling to flexural buckling with the increase in the slenderness ratio. The failure modes of all OB140 specimens were deformation concentration, except for one long specimen, whose failure mode was flexural buckling. When the slenderness ratios of the specimens were less than 55, the failure modes were controlled by local buckling. Finite element models were built using ABAQUS software and validated to further analyze the mechanical behavior of the BOCCFSs. A parametric study was conducted and used to explore a wide design space. The numerical analysis results showed that when the screw spacing was between 150 mm and 450 mm, the difference in the maximum compression strength values of the specimens was less than 4%. The applicability and effectiveness of the design methods in Chinese GB50018-2002 and AISI-S100-2016 for calculating the compression strength values of the BOCCFSs were evaluated. The prediction methods based on the assumptions produced predictions of the strength that were between 33% to 10% conservative as compared to the tests and the finite element analysis.

Key Words
built-up open-section columns; cold-formed steel; compression tests; design method; mechanical behavior; numerical analysis

Address
Shaofeng Nie, Cunqing Zhao, Zhe Liu, Yong Han, Tianhua Zhou and Hanheng Wu:School of Civil Engineering, Chang'an University, Xi'an, 710061, China



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