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Volume 48, Number 4, August25 2023

A coupled wall consists of two or more reinforced concrete (RC) shear walls (SWs) connected by RC coupling beams (CBs) or steel CBs (hybrid-coupled walls). To fill the gap in the literature on the plastic hinge length of coupled walls, including coupled and hybrid-coupled shear walls, a parametric study using experimentally validated numerical models was conducted considering the axial stress ratio (ASR) and coupling ratio (CR) as the study variables. A total of sixty numerical models, including both coupled and hybrid-coupled SWs, have been developed by varying the ASR and CR within the ranges of 0.027-0.25 and 0.2-0.5, respectively. A detailed analysis was conducted in order to estimate the ultimate drift, ultimate capacity, curvature profile, yielding height, and plastic hinge length of the models. Compared to hybrid-coupled SWs, coupled SWs possess a relatively higher capacity and curvature. Moreover, increasing the ASR changes the walls' behavior to a columnlike member which decreases the walls' ultimate drift, ductility, curvature, and plastic hinge length. Increasing the CR of the coupled SWs increases the walls' capacity and the risk of abrupt shear failure but decreases the walls' ductility, ultimate drift and plastic hinge length. However, CR has a negligible effect on hybrid-coupled walls' ultimate drift and moment, curvature profile, yielding height and plastic hinge length. Lastly, using the obtained results two equations were derived as a function of CR and ASR for calculating the plastic hinge length of coupled and hybrid-coupled SWs.

Key Words
axial stress ratio; coupled shear walls; coupling beams; coupling ratio; hybrid-coupled shear walls; plastic hinge length

Abouzar Jafari:State Key Laboratory of Disaster Reduction in Civil Engineering, College of Civil Engineering,
Tongji University, 1239 Siping Rd, Shanghai 200092, China

Meysam Beheshti, Amir Ali Shahmansouri and Habib Akbarzadeh Bengar:Department of Civil Engineering, Faculty of Engineering and Technology, University of Mazandaran, Babolsar, Iran

To avoid premature damage to the connection joints of a conventional precast concrete shear wall, a new precast concrete shear wall system (NPSW) based on a plastic damage relocation design concept was proposed. Five specimens, including one monolithic cast-in-place concrete shear wall (MSW) as a reference and four NPSWs with different connection details (TNPSW, INPSW, HNPSW, and TNPSW-N), were designed and tested by lateral low-cyclic loading. To accurately assess the damage relocation effect and quantify the damage and deformation, digital image correlation (DIC) and conventional data acquisition methods were used in the experimental program. The concrete cracking development, crack area ratio, maximum residual crack width, curvature of the wall panel, lateral displacement, and deformed shapes of the specimens were investigated. The results showed that the plastic damage relocation design concept was effective; the initial cracking occurred at the bottom of the precast shear wall panel (middle section) of the proposed NPSWs. The test results indicated that the crack area ratio and the maximum residual crack width of the NPSWs were less than those of the MSW. The NPSWs were deformed continuously; significant distortions did not occur in their connection regions, demonstrating the merits of the proposed NPSWs. The curvatures of the middle sections of the NPSWs were lower than that of the MSW after a drift ratio of 0.5%. Among the NPSWs, HNPSW demonstrated the best performance, as its crack area ratio, concrete damage, and maximum residual crack width were the lowest.

Key Words
damage; deformation; digital image correlation; experimental study; precast concrete shear wall

Dayang Wang and Shenchun Xu:School of Civil Engineering, Guangzhou University, Guangzhou 510006, China

Qihao Han: 1)School of Civil Engineering, Guangzhou University, Guangzhou 510006, China
2) School of Civil and Surveying & Mapping Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China

Zhigang Zheng:State Key Laboratory of Nuclear Power Safety Monitoring Technology and Equipment, China Nuclear Power Engineering Co. Ltd.,
Shenzhen 518172, China

Quantian Luo:School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Sydney 2007, Australia

Jihua Mao:Guangzhou Guangjian Construction Engineering Testing Center Co., Ltd., Guangzhou 510699, China

In order to strengthen the reinforced concrete T-beams having insufficient shear strength, several strengthening techniques are available in the literature. In this study, three different strengthening strategies were numerically studied. First one is affixing steel plates to the beam surfaces. Second one includes tightening external steel bars vertically similar to beam stirrups. The last one is simultaneous application of these two strengthening procedures which is particularly proposed in this work. Available experimental test series in the literature were handled in the study. Finite element (FE) models of reinforced concrete beam specimens having sufficient (Beam-1) and low shear capacity (Beam-2) were created within ABAQUS environment. Strengthened beams with different techniques were also modelled to reflect improved shear capacity. FE simulations made it possible to investigate parameters that were not examined during the previous experimental studies. The results of the analyses were then compared and found consistent with the experimentally obtained data. Experimental and FEM analysis results are in agreement between 1% (closest) and 6%. (maximum). Beam-2 was stregthened with 5 new porposed methods. The rate of increase in shear strength varies between 33% and 64%. It was found that, the strengthening techniques were fairly useful in improving the shear capacity of the considered girder. The model with the proposed strengthening alternative has accomplished a higher load carrying capacity, ductility and stiffness than all of the other models.

Key Words
finite element; nonlinear analysis; shear strengthening; steel clamp; steel plate; T-beam

Yunus Dere, Yasin Onuralp Ozkilic, Ali Serdar Ecemiş and Hasan Husnu Korkmaz:Department of Civil Engineering, Necmettin Erbakan University, 42100, Konya, Turkey

In this paper, dynamic and static bending of ball modelled by nanocomposite microbeam by nanoparticles seeing agglomeration is presented. The structural damping is considered by Kelvin-Voigt model. The agglomeration effects are assumed using Mori-Tanaka model. The football ball is modeled by third order shear deformation theory (TSDT). The motion equations are derived by principle of Hamilton's and energy method assuming size effects on the basis of Eringen theory. Using differential quadrature method (DQM) and Newmark method, the static and dynamic deflections of the structure are obtained. The effects of agglomeration and CNTs volume percent, damping of structure, nonlocal parameter, length and thickness of micro-beam are presented on the static and dynamic deflections of the nanocomposite structure. Results show that with increasing CNTs volume percent, the maximum dimensionless dynamic deflection is reduced about 17%. In addition, assuming CNTs agglomeration increases the dimensionless dynamic deflection about 14%. It is also found that with increasing the CNTs volume percent from 0 to 0.15, the static deflection is decreased about 3 times due to the enhance in the stiffness of the structure. In addition, with enhancing the nonlocal parameters, the dynamic deflection is increased about 3.1 times.

Key Words
agglomeration effects; CNTs; dynamic response; micro-beam; TSDT

Chenghong Long:Sport Department, Chongqing Jiaotong University, Chongqing 400074, China

Dan Wang:School of Physical Education, Hubei University of Science and Technology, Xianning, 437100, Hubei, China

H.B. Xiang:Department of Civil Engineering, Murdoch University of Western Australia

This research presents an advanced finite element formulation for analyzing the vibratory behaviour of tapered composite shaft rotors, taking into account the impact of the draft angle on the stiffness of the composite shaft laminate. The vibration response of the shaft rotating around its axis is studied using both the finite element hierarchical method and the classical finite element formulation, based on the theory of transverse shear deformation, rotary inertia, gyroscopic effect, and coupling effect due to the stratification of the composite layers of the shaft. The study also includes the development of a program to calculate the Eigen frequencies and critical speeds of the system, and the obtained results are compared with those available in the literature. This research provides valuable insights into the vibratory behaviour of tapered composite shaft rotors and can be useful for designing and optimizing such structures in various industrial applications.

Key Words
composite structures; dynamic analysis; structural analysis; elasticity; vibration/vibration analysis

Zahi Rachid:1)Laboratory of Mechanics of Structures and Solids LMSS, University of Sidi Bel Abbes, Algeria
2)University of Relizane

Sahli Abderahmane and Moulgada Abdelmadjid:Department of Mechanical Engineering, Laboratory Mechanics Physics of Materials (LMPM), University of Sidi Bel Abbes

Ziane Noureddine:UDL de Sidi Bel Abbes. Laboratoire des Structures et Materiaux Avances

Refassi Kaddour:Laboratory of Mechanics of Structures and Solids LMSS, University of Sidi Bel Abbes, Algeria

This paper investigates the stability of a bi-directional functionally graded (BD-FG) cylindrical beam made of imperfect concrete, taking into account size-dependency and the effect of geometry on its stability behavior. Both buckling and dynamic behavior are analyzed using the modified coupled stress theory and the classical beam theory. The BD-FG structure is created by using porosity-dependent FG concrete, with changing porosity voids and material distributions along the pipe radius, as well as uniform and nonuniform radius functions that vary along the beam length. Energy principles are used to generate partial differential equations (PDE) for stability analysis, which are then solved numerically. This study sheds light on the complex behavior of BD-FG structures, and the results can be useful for the design of stable cylindrical microstructures.

Key Words
functionally graded materials; nonuniform cross-section; numerical analysis; stability analysis; truncated conical beam

Yunzhong Dai:1)Intelligent Manufacturing Institute, Yibin Vocational and Technical College, Yibin 644003, Sichuan, China
2)Sichuan Dawn Precision Technology Co., Ltd., Meishan 620460, Sichuan, China
3)School of Aeronautics and Astronautics, University of Electronic Science and Technology of China, Chengdu 611731, Sichuan, China

Zhiyong Jiang:Engineering Comprehensive Training Center, Guilin University of Aerospace Technology, Guilin 541004, Guangxi, China

Kuan-yu Chen:Yulin Normal University, School of Political Science and Law, Yulin 537000, Guangxi, China

Kuan-yu Chen, Duquan Zuo, Mostafa habibi, H. Elhosiny Ali and Ibrahim Albaijan

Mostafa habibi:1)Faculty of Architecture and Urbanism, UTE University, Calle Rumipamba S/N and Bourgeois, Quito, Ecuador
2)Department of Biomaterials, Saveetha Dental College and Hospital,
Saveetha Institute of Medical and Technical Sciences, Chennai 600 077, India
3)Center of Excellence in Design, Robotics, and Automation, Department of Mechanical Engineering,
Sharif University of Technology, Azadi Avenue, P.O. Box 11365-9567, Tehran, Iran
4)Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam

H. Elhosiny Ali:Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia

Ibrahim Albaijan:Mechanical Engineering Department, College of Engineering at Al Kharj,
Prince Sattam Bin Abdulaziz University, Al Kharj 11942, Saudi Arabia

Concrete-filled steel tubes are among the most efficient compressive structural members because the strength of the concrete is enhanced given that the surrounding steel tube confines the concrete laterally and the steel tube is restrained with regard to inward deformation due to the concrete existing inside. Accurate estimations of the ultimate compressive strength of CFT are important for efficient designs of CFT members. In this study, an analytical procedure that directly formulates the interaction between the concrete and steel tube by considering the nonlinear Poisson effect and stress-strain curve of the concrete including the confinement effect is proposed. The failure stress of concrete and von-Mises failure yield criterion of steel were used to consider multi-dimensional stresses. To verify the prediction capabilities of the proposed analytical procedure, 99 circular CFT experimental data instances from other studies were used for a comparison with AISC, Eurocode 4, and other researchers' predictions. From the comparison, it was revealed that the proposed procedure more accurately predicted the ultimate compressive strength of a circular CFT regardless of the range of the design variables, in this case the concrete compressive strength, yield strength of the steel tube and diameter relative to the thickness ratio of the tube.

Key Words
CFT; confinement; hoop stress; nonlinear Poisson effect; ultimate strength

Yu-A Kim and Jin-Kook Kim:Department of Civil Engineering, Seoul National University of Science and Technology, 232 Gongneung-ro, Nowon-gu, Seoul 01811,
Republic of Korea

Ju-young Hwang:Department of Civil Engineering, Dong-Eui University, Busan 47340, Republic of Korea

In this paper, a new energy-efficient semi-active hybrid bulk damper is developed that is cost-effective for use in structural applications. In this work, the possibility of active and semi-active component configurations combined with suitable control algorithms, especially vibration control methods, is explored. The equations of motion for a container bridge equipped with an MDOF Mass Tuned Damper (M-TMD) system are established, and the combination of excitation, adhesion, and control effects are performed by a proprietary package and commercial custom submodel software. Systematic methods for the synthesis of structural components and active systems have been used in many applications because of the main interest in designing efficient devices and high-performance structural systems. A rational strategy can be established by properly controlling the master injection frequency parameter. Simulation results show that the multiscale model approach is achieved and meets accuracy with high computational efficiency. The M-TMD system can significantly improve the overall response of constrained structures by modestly reducing the critical stress amplitude of the frame. This design can be believed to build affordable, safe, environmentally friendly, resilient, sustainable infrastructure and transportation.

Key Words
artificial intelligence; energy equations; multiple-tuned mass dampers structural control; resilient and sustainable infrastructures; tuned mass damper

ZY Chen, Yahui Meng and Ruei-Yuan Wang:School of Science, Guangdong University of Petrochemical Technology, Maoming 525000, Guangdong, China

T. Chen:California Institute of Technology, Pasadena, CA 91125, USA

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