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CONTENTS
Volume 90, Number 4, May25 2024
 


Abstract
Triple-tower double-cable suspension bridges have increased confinement stiffness imposed by the main cable on the middle tower, which has bright application prospects. However, vertical bending and torsional vibrations of the double-cable and the girder are coupled in such bridges due to the hangers. In particular, the bending vibration of the towers in the longitudinal direction and torsional vibrations about the vertical axis influence the vertical bending and torsional vibrations of the stiffening girders, respectively. The conventional analytical algorithm for assessing the dynamic features of the suspension bridge is not directly applicable to this type of bridge. This study attempts to mitigate this problem by introducing an analytical algorithm for solving the triple-tower double-cable suspension bridge's natural frequencies and mode shapes. D'Alembert's principle is employed to construct the differential equations of the vertical bending and torsional vibrations of the stiffening girder continuum in each span. Vibrations of stiffening girders in each span are interrelated via the vibrations of the main cables and the bridge towers. On this basis, the natural frequencies and mode shapes are derived by separating variables. The proposed algorithm is then applied to an engineering example. The natural frequencies and mode shapes of vertical bending and torsional vibrations derived by the analytical algorithm agreed well with calculations via the finite element method. The fundamental frequency of vertical bending and first- and second-order torsion frequencies of double-cable suspension bridges are much higher than those of single-cable suspension bridges. The analytical algorithm has high computational efficiency and calculation accuracy, which can provide a reference for selecting appropriate structural parameters to meet the requirements of dynamics during the preliminary design.

Key Words
analytical algorithm; double-cable; dynamic characteristics; free vibration; suspension bridge; triple-tower

Address
Wen-ming Zhang: The Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing 211189, China; State Key Laboratory of Safety, Durability and Healthy Operation of Long Span Bridges, Southeast University, Nanjing 210096, China
Yu-peng Chen, Shi-han Wang, Xiao-fan Lu: The Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast University, Nanjing 211189, China

Abstract
This paper aims to investigate the seismic behavior of double steel plate and concrete composite shear wall (DSCW) of shield buildings in nuclear power engineering through experimental study. Hence, a total of 10 specimens were tested to investigate the hysteretic performance of DSCW specimens in detail, in terms of load vs. displacement hysteretic curves, skeleton curves, failure modes, flexural strength, energy dissipation capacity. The experimental results indicated that the thickness of steel plate, vertical load and stiffener have great influence on the shear bearing capacity of shear wall, and the stud space has limited influence on the shear capacity. And finally, a novel simplified formula was proposed to predict the shear bearing capacity of composite shear wall. The predicted results showed satisfactory agreement with the experimental results.

Key Words
double steel plate and concrete composite shear wall (DSCW); influencing factors; in-plane cyclic load; nuclear power engineering; shear bearing capacity

Address
Xiaohu Li, Tao Zhang, Lei Li, Ke Shi: School of Civil Engineering and Environment, Zhengzhou University of Aeronautics, Zhengzhou 450000, PR China
Hao Luo, Xihao Ren: China Construction Seventh Engineering Division, Co. Ltd., Zhengzhou 450000, PR China

Abstract
Due to the fact that the mechanism of the effects of temperature and initial geometric imperfection on low-velocity impact problem of axially moving plates is not yet clear, the present paper is to fill the gap. In the present paper, the nonlinear dynamic behavior of axially moving imperfect graphene platelet reinforced metal foams (GPLRMF) plates subjected to lowvelocity impact in thermal environment is analyzed. The equivalent physical parameters of GPLRMF plates are estimated based on the Halpin-Tsai equation and the mixing rule. Combining Kirchhoff plate theory and the modified nonlinear Hertz contact theory, the nonlinear governing equations of GPLRMF plates are derived. Under the condition of simply supported boundary, the nonlinear control equation is discretized with the help of Gallekin method. The correctness of the proposed model is verified by comparison with the existing results. Finally, the time history curves of contact force and transverse center displacement are obtained by using the fourth order Runge-Kutta method. Through detailed parameter research, the effects of graphene platelet (GPL) distribution mode, foam distribution mode, GPL weight fraction, foam coefficient, axial moving speed, prestressing force, temperature changes, damping coefficient, initial geometric defect, radius and initial velocity of the impactor on the nonlinear impact problem are explored. The results indicate that temperature changes and initial geometric imperfections have significant impacts.

Key Words
axial motion; geometric imperfection; graphene platelet; low-velocity impact; thermal environment

Address
G.L. She: Key Laboratory of Architectural Acoustic Environment of Anhui Higher Education Institutes, Anhui Jianzhu University, Hefei 230009, China; College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China
J.P. Song: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

Abstract
Investigating the impact of openings on the structural behavior of ferrocement I-beams with two distinct types of reinforcing metallic and non-metallic meshes is the primary goal of the current study. Up until failure, eight 250x200x2200 mm reinforced concrete I-beams were tested under flexural loadings. Depending on the kind of meshes used for reinforcement, the beams are split into two series. A control I-beam with no openings and three beams with one, two, and three openings, respectively, are found in each series. The two series are reinforced with three layers of welded steel meshes and two layers of tensar meshes, respectively, in order to maintain a constant reinforcement ratio. Structural parameters of investigated beams, including first crack, ultimate load, deflection, ductility index, energy absorption, strain characteristics, crack pattern, and failure mode were reported. The number of mesh layers, the volume fraction of reinforcement, and the kind of reinforcing materials are the primary factors that vary. This article presents the outcomes of a study that examined the experimental and numerical performance of ferrocement reinforced concrete I-beams with and without openings reinforced with welded steel mesh and tensar mesh separately. Utilizing ANSYS-16.0 software, nonlinear finite element analysis (NLFEA) was applied to illustrate how composite RC I-beams with openings behaved. In addition, a parametric study is conducted to explore the variables that can most significantly impact the mechanical behavior of the proposed model, such as the number of openings. The FE simulations produced an acceptable degree of experimental value estimation, as demonstrated by the obtained experimental and numerical results. It is also noteworthy to demonstrate that the strength gained by specimens without openings reinforced with tensar meshes was, on average, 22% less than that of specimens reinforced with welded steel meshes. For specimens with openings, this value is become on average 10%.

Key Words
Ansys-16; composite material; experimental; ferrocement; NLFE modeling; openings; RC I-beams

Address
Yousry B.I. Shaheen, Ghada M. Hekal: Civil Engineering Department, Faculty of Engineering, Menoufia University, Menoufia, Egypt
Ayman M. Elshaboury: Construction Engineering Department, Higher Institute of Engineering and Technology, Beheira, Egypt
Ashraf M. Mahmoud: Civil Engineering Department, Faculty of Engineering, Modern University for Technology and Information (MTI), Al-Mokattam, Cairo, Egypt

Abstract
The present study focuses on the effect of extension-bending coupling on the elastic stability (buckling) of laminated composite plates. These plates will be loaded under uni-axial or bi-axial in-plane mechanical loads, especially in the orthotropic or anti-symmetric cross-angle cases. The main objective is to find a limit where we can approximate the elastic stability behavior of angularly crossed anti-symmetric plates by the simple behavior of specially orthotropic plates. The contribution of my present study is to predict the explicit effect of extension-flexion coupling on the elastic stability of this type of panel. Critically, a parametric study is carried out, involving the search for the critical buckling load as a function of deformation mode, aspect ratio, plate anisotropy ratio and finally the study of the effect of lamination angle and number of layers on the contribution of extension-flexure coupling in terms of plate buckling stability. We use first-order shear deformation theory (FSDT) with a correction factor of 5/6. Simply supported conditions along the four boundaries are adopted where we can develop closed-form analytical solutions obtained by a Navier development.

Key Words
buckling; composite materials; coupling; critical load; elastic instability

Address
H. Mataich, A. El Amrani, B. El Amrani: Laboratory of Mathematics, Modeling and Applied Physics, High Normal School, Sidi Mohamed Ben Abdellah University, 30040 Fez, Morocco
J. El Mekkaoui: Laboratory of Technology and Innovations, High School of Technology, Sidi Mohamed Ben Abdellah University, 30040 Fez, Morocco

Abstract
We looked at how the damping qualities of epoxy composites changed when different amounts of graphite nanoplatelets (GNP) were added, from 0% to 6% by weight. A mix of free and forced vibration tests helped us find the key GNP content that makes the damper ability better the most. We also created a Representative Volume Element (RVE) model to guess how the alloys would behave mechanically and checked these models against testing data. An Artificial Neural Network (ANN) was also used to guess how these compounds would react to motion. With proper hyperparameter tweaking, the ANN model showed good correlation (R2=0.98) with actual data, indicating its ability to predict complex material behavior. Combining these methods shows how GNPs impact epoxy composite mechanical properties and how machine learning might improve material design. We show how adding GNPs to epoxy composites may considerably reduce vibration. These materials may be used in industries that value vibration damping.

Key Words
Artificial Neural Network; damping; epoxy; graphite nanoplatelet; machine learning; Representative Volume Element (RVE); vibration

Address
Hatam K. Kadhom and Aseel J. Mohammed: Department of Electromechanical Engineering, University of Technology-Iraq, Baghdad, Iraq

Abstract
Nanocomposite-reinforced concrete systems have gained increasing attention in bridge construction due to their enhanced mechanical properties and durability. Understanding the transient dynamics of these advanced materials is crucial for ensuring the structural integrity and performance of bridge infrastructure under dynamic loading conditions. This paper presents a comprehensive study of the measurement techniques employed for assessing the transient dynamics of nanocompositereinforced concrete systems in bridge construction applications. A numerical method, including modal analysis are discussed in detail, highlighting their advantages, limitations, and applications. Additionally, recent advancements in sensor technologies, data acquisition systems, and signal processing techniques for capturing and analyzing transient responses are explored. The paper also addresses challenges and opportunities in the measurement of transient dynamics, such as the characterization of nanocomposite-reinforced concrete materials, the development of accurate numerical models, and the integration of advanced sensing technologies into bridge monitoring systems. Through a critical review of existing literature and case studies, this paper aims to provide insights into best practices and future directions for the measurement of transient dynamics in nanocompositereinforced concrete systems, ultimately contributing to the design, construction, and maintenance of resilient and sustainable bridge infrastructure.

Key Words
concrete systems; dynamic loading; mathematical simulation; nanocomposite reinforcement; transient dynamics

Address
Shuzhen Chen: School of Civil Engineering, Chongqing Vocational Institute of Engineering, Chongqing, 402260, China
Hou Chang-ze: Chongqing Shangshan Real Estate Co., Ltd, Chongqing, 400700, China
Gongxing Yan: School of Intelligent Construction, Luzhou Vocational and Technical College, Luzhou 646000, Sichuan, China; Luzhou Key Laboratory of Intelligent Construction and Low-carbon Technology, Luzhou 646000, China
M. Atif: Department of Physics and Astronomy, College of Science, King Saud University, PO Box 2455, Riyadh 11451, Saudi Arabia

Abstract
In the current work, the effect of rotation and mechanical force on a nonlocal micropolar thermoelastic solid with temperature-dependent properties was discussed using Erigen

Key Words
mechanical force; micropolar; nonlocal parameter; rotation; temperature dependent properties

Address
Samia M. Said, Mohamed I.A. Othman: Department of Mathematics, Faculty of Science, Zagazig University, P.O. Box 44519, Zagazig, Egypt
Elsayed M. Abd-Elaziz: Ministry of Higher Education, Zagazig Higher Institute of Engineering & Technology, Zagazig, Egypt


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