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CONTENTS
Volume 42, Number 3, February 2022
 

Abstract
In the present study, structural behavior of steel beams strengthened with CFRP strips and cables was investigated by a series of experiments. For this purpose, two groups of experimental studies were carried out: one for the beam series strengthened only with CFRP strips and the other for the steel beam series strengthened with CFRP strips and prestressed wires. From this test, it is found that the flexural stiffness and strength of the steel beams strengthened with CFRP strips and cables were significantly improved comparing to the un-strengthened one. Three failure modes such as sudden de-bonding, splitting and rupturing of CFRP strips were observed. The ultimate tensile strains of attached CFRP strips on the steel beams were noticed in the range between 8,000µε and 11,000µε and this result disclose the perfect composite reaction CFRP strips and steel beams.

Key Words
carbon fiber reinforced plastic (CFRP) strips; prestressed cables; steel beam

Address
Department of Civil Engineering, Dongseo University, San 69-1, Churae 2 dong, Sasang ku, Busan 617-716, South Korea

Abstract
Steel–concrete–steel composite structures with bidirectional webs (SCSBWs) are used in large-scale projects and exhibit good mechanical performances and constructional efficiency. The shear behaviors of SCSBW deep beam members in key joints or in locations subjected to concentrated forces are of concern in design. To address this issue, experimental program is investigated to examine the deep-beam shear behaviors of SCSBWs, in which the cracking process and force transfer mechanism are revealed. Compared with the previously proposed truss model, it is found that a strut-and-tie model is more suitable for describing the shear mechanism of SCSBW deep beams with a short span and sparse transverse webs. According to the experimental analyses, a new model is proposed to predict the shear capacities of SCSBW deep beams. This model uses strut-and-tie concept and introduces web shear and dowel action to consider the coupled multi mechanisms. A stress decomposition method is used to distinguish the contributions of different shear-transferring paths. Based on case studies, a simplified model is further developed, and the explicit solution is derived for design efficiency. The proposed models are verified using experimental data, which are proven to have good accuracy and efficiency and to be suitable for practical application.

Key Words
composite structure; deep beam; experiment; mechanical model; sandwich structure; shear

Address
Yu-Tao Guo: Key Lab. of Civil Engineering Safety and Durability of China Education Ministry, Dept. of Civil Engineering, Tsinghua University, Beijing, China 100084

Xin Nie: Key Lab. of Civil Engineering Safety and Durability of China Education Ministry, Dept. of Civil Engineering, Tsinghua University, Beijing, China 100084

Jian-Sheng Fan: Beijing Engineering Research Center of Steel and Concrete Composite Structures, Dept. of Civil Engineering, Tsinghua University, Beijing, China 100084

Mu-Xuan Tao: Key Lab. of Civil Engineering Safety and Durability of China Education Ministry, Dept. of Civil Engineering, Tsinghua University, Beijing, China 100084

Abstract
Shear connectors are key elements that ensure integrity in a composite system. The primary purpose of a shear connector is to bring a high degree of interaction between composite elements. A wide variety of connectors are available for hot-rolled composite construction, connected to the beam through welding. However, with cold-formed members being very thin, welding of shear connectors is not desirable in cold-formed composite constructions. Shear connectors for cold-formed elements are limited in studies as well as in the market. Hence in this study, three different types of shear connectors, namely, single-channel, double channel, and self–tapping screw, were considered, and their performance assessed by the Push-out test as per Eurocode 4. The connection between channel shear connectors and the beam was made using self-tapping screws to avoid welding. The performance of the connectors was analyzed based on their ultimate capacity, characteristic capacity, ductility, and slippage during loading. Strength to weight ratio was also carried out to understand the proposed connectors' suitability for conventional ones. The results showed relatively higher initial stiffness and ductility for double channel connectors than other connectors. Also, self-tapping screws had a higher strength to weight ratio with low ductility.

Key Words
channel connector; cold-formed composite beam; push-out test; shear connectors

Address
Senthilkumar Rajendran:Department of Civil Engineering, National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamil Nadu-620015

Jayabalan Perumalsamy:Department of Civil Engineering, National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamil Nadu-620015

Divya Mohanraj:Department of Civil Engineering, National Institute of Technology Tiruchirappalli, Tiruchirappalli, Tamil Nadu-620015

Abstract
This paper studies the lateral impact behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) filled double-skin steel tubular (UHPFRCFDST) columns. The impact force, midspan deflection, and strain histories were recorded. Based on the test results, the influences of drop height, axial load, concrete type, and steel tube wall thickness on the impact resistance of UHPFRCFDST members were analyzed. LS-DYNA software was used to establish a finite element (FE) model of UHPFRC filled steel tubular members. The failure modes and histories of impact force and midspan deflection of specimens were obtained. The simulation results were compared to the test results, which demonstrated the accuracy of the finite element analysis (FEA) model. Finally, the effects of the steel tube thickness, impact energy, type of concrete and impact indenter shape, and void ratio on the lateral impact performances of the UHPFRCFDST columns were analyzed.

Key Words
drop hammer; Finite Element Analysis (FEA); steel tube; ultra-high performance fiber-reinforced concrete

Address
Jie Li:Tianjin Key Laboratory of Civil Structure Protection and Reinforcement, Tianjin Chengjian University, Tianjin 300384, China

Weiqiang Wang: College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China

Chengqing Wu:School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia

Zhongxian Liu:Tianjin Key Laboratory of Civil Structure Protection and Reinforcement, Tianjin Chengjian University, Tianjin 300384, China

Pengtao Wu:Tianjin Key Laboratory of Civil Structure Protection and Reinforcement, Tianjin Chengjian University, Tianjin 300384, China

Abstract
In this study, an estimation regarding nonlocal shell model based on wave propagation approach has been considered for vibrational behavior of the double walled carbon nanotubes with distinct nonlocal parameters. Vibrations of double walled carbon nanotubes for chiral indices (8, 3) have been analyzed. The significance of small scale is being perceived by developing nonlocal Love shell model. The influence of changing mechanical parameter Poisson's ratio has been investigated in detail. The dominance of boundary conditions via nonlocal parameter is shown graphically. It is found that on increasing the Poisson's ratio, the frequencies increases. It is noted that the frequencies of clamped-clamped frequencies are higher than that of simply-supported and clamped-free edge conditions. The outcomes of frequencies are tested with earlier computations.

Key Words
double-walled CNTs; love shell theory; nonlocal parameter; poisson

Address
Sami Alghamdi:Electrical and Computer Engineering Department King Abdulaziz, University, Jeddah, Saudi Arabia

Muzamal Hussain:Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan

Mohamed A. Khadimallah:Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 16273, Saudi Arabia/ Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia

Sehar Asghar:Department of Mathematics, Govt. College University Faisalabad, 38040, Faisalabad, Pakistan

Emad Ghandourah:Department of Nuclear Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia

Ahmed Obaid M. Alzahrani:Center of Nanotechnology, King Abdulaziz University, Jeddah, Saudi Arabia/ Physics Department, Faculty of Science, King Abdulaziz, University, Jeddah, Saudi Arabia

M.A. Alzahrani:Mechanical Engineering Department, Faculty of Science, King Abdulaziz, University, Jeddah, Saudi Arabia



Abstract
This paper presents an experimental and a numerical investigation of a H-beam – composite box column joint fabricated with two new inner diaphragms and a continuous inner diaphragm. The main objective of the current research project is to investigate the structural performance of the newly developed inner diaphragms under a cyclic loading protocol. Hysteretic behaviour of the composite joints is analysed to investigate the structural performance of the new and continuous inner diaphragms. This paper compares the result of the finite element (FE) models with the new and continuous inner diaphragms against their counterpart experimental results. To produce a design criterion for the newly developed inner diaphragms, yielding or failure area of the inner diaphragms under tensile stress is analysed from the FE results.

Key Words
composite beam-column joint; finite element model; new inner diaphragms; seismic behaviour

Address
Mahbub Khan:School of Civil Engineering, University of Sydney, NSW, Australia

Brian Uy:School of Civil Engineering, University of Sydney, NSW, Australia

Jin W Kim:Steel Solution Research Lab, POSCO, Republic of Korea

Abstract
In this work, limit elastic speed analysis of functionally graded porous rotating disks has been reported. The work proposes an effective approach for modeling the mechanical properties of a porous functionally graded rotating disk. Four different types of porosity models namely: uniform, symmetric, inner maximum, and outer maximum distribution are considered. The approach used is the variational principle, and the solution has been achieved using Galerkin's error minimization theory. The study aims to investigate the effect of grading indices, aspect ratio, porosity volume fraction, and porosity types on limit angular speed for uniform and variable disk geometries of constant mass. To validate the current study, finite element analysis has been used, and there is good agreement between the two methods. The study yielded a decrease in limit speed as grading indices and aspect ratio increase. The porosity volume fraction is found to be more significant than the aspect ratio effect. The research demonstrates a range of operable speeds for porous and non-porous disk profiles that can be used in industries as design data. The results show a significant increase in limit speed for an exponential disk when compared to other disk profiles, and thus, the study demonstrates a range of FG-based structures for applications in industries that will not only save material (lightweight structures) but also improve overall performance.

Key Words
effective yield stress; Halpin-Tsai; limit elastic speed analysis; porous FG disk; variational principle

Address
Royal Madan:Department of Mechanical Engineering, National Institute of Technology Raipur (C.G)-492010, India

Shubhankar Bhowmick:Department of Mechanical Engineering, National Institute of Technology Raipur (C.G)-492010, India

Lazreg Hadji:Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City 70000, Vietnam/ Laboratory of Geomatics and Sustainable Development, University of Tiaret, 14000, Algeria

Abdelouahed Tounsi:YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea/ Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

Abstract
This investigation in fluid mechanics surrounds around the variety of flow problems for different fluids along the stretching cylinder. Numerical procedure is carried out for the obtained resultant equations by Keller-Box technique. Numerical study of laminar, steady, viscous and incompressible two dimensional boundary layer flow of effects of suction and blowing on boundary layer slip flow of Casson fluid along permeable exponentially stretching cylinder has been carried out in the present draft. physical parameters i.e., Nusselt number and skin friction coefficient, suction parameter and the local Reynold number are investigated on velocity profile and elaborated through proper graphs and table.

Key Words
numerical study; Reynold number; skin friction; velocity profile

Address
Mudassar Jalil:Department of Mathematics, COMSATS Institute of Information Technology, Park Road, Chak Shahzad, 44000 Islamabad, Pakistan

Waheed Iqbal:Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan

Muzamal Hussain:Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan

Mohamed A. Khadimallah:Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 11942, Saudi Arabia

Adil Alshoaibi:Department of Physics, College of Science, King Faisal University, Al-Hassa, P.O Box, Hofuf, 31982, Saudi Arabia

Jamel Baili:Department of Computer Engineering, College of Computer Science, King Khalid University, Abha 61413, Saudi Arabia/ Higher Institute of Applied Science and Technology of Sousse (ISSATS), Cité Taffala (Ibn Khaldoun) 4003 Sousse,
University of Souse, Tunisia

Khaled Mohamed Khedher:Department of Civil Engineering, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia/ Department of Civil Engineering, High Institute of Technological Studies, Mrezgua University Campus, Nabeul 8000, Tunisia
9YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Kore

Elimam Abdallah Ali:Prince Sattam Bin Abdulaziz University, College of Engineering, Civil Engineering Department, BP 655, Al-Kharj, 11942, Saudi Arabia

Abdelouahed Tounsi:YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea/ Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran,
Eastern Province, Saudi Arabia


Abstract
The existing researches on the dynamics of the fluid-conveying pipes only focus on stability and vibration problems, and there is no literature report on the wave propagation of the fluid-conveying pipes. Therefore, the purpose of this paper is to explore the propagation characteristics of longitudinal and flexural waves in the fluid-conveying pipes. First, it is assumed that the material properties of the fluid-conveying pipes vary based on a power function of the thickness. In addition, it is assumed that the material properties of both the fluid and the pipes are closely depended on temperature. Using the Euler-Bernoulli beam equation and based on the linear theory, the motion equations considering the thermal-mechanical-fluid coupling is derived. Then, the exact expressions of phase velocity and group velocity of longitudinal waves and bending waves in the fluidconveying pipes are obtained by using the eigenvalue method. In addition, we also studied the free vibration frequency characteristics of the fluid-conveying pipes. In the numerical analysis, we successively studied the influence of temperature, functional gradient index and liquid velocity on the wave propagation and vibration problems. It is found that the temperature and functional gradient exponent decrease the phase and group velocities, on the contrary, the liquid flow velocity increases the phase and group velocities. However, for vibration problems, temperature, functional gradient exponent parameter, and fluid velocity all reduce the natural frequency.

Key Words
conveying-fluid pipes; group velocity; phase velocity; vibration; wave propagation

Address
Yi-Wen Zhang:College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

Gui-Lin She:College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

Abstract
Superior to traditional welded studs, high strength friction-grip bolted shear connectors facilitate the assembling and demounting of the composite members, which maximizes the potential for efficiency in the construction and retrofitting of new and old structures respectively. Hence, it is necessary to investigate the structural properties of high strength friction-grip bolts used in steel concrete composite beams. By means of push-out tests, an experimental study was conducted on post-installed high strength friction-grip bolts, considering the effects of different bolt size, concrete strength, bolt tensile strength and bolt pretension. The test results showed that bolt shear fracture was the dominant failure mode of all specimens. Based on the loadslip curves, uplifting curves and bolt tensile force curves between the precast concrete slab and steel beam obtained by push-out tests, the anti-slip performance of steel-concrete interface and shear behavior of bolt shank were studied, including the quantitative analysis of anti-slip load, and anti-slip stiffness, frictional coefficient, shear stiffness of bolt shank and ultimate shear capacity. Meanwhile, the interfacial anti-slip stiffness and shear stiffness of bolt shank were defined reasonably. In addition, a total of 56 push-out finite element models verified by the experimental results were also developed, and used to conduct parametric analyses for investigating the shear behavior of high-strength bolted shear connectors in steel-concrete composite beams. Finally, on ground of the test results and finite element simulation analysis, a new design formula for predicting shear capacity was proposed by nonlinear fitting, considering the bolt diameter, concrete strength and bolt tensile strength. Comparison of the calculated value from proposed formula and test results given in the relevant references indicated that the proposed formulas can give a reasonable prediction.

Key Words
high-strength bolt; steel-concrete composite beams; shear connectors; push-out tests; rapid assembling and demounting

Address
Ying Xing:College of Civil Engineering, Hunan University, Changsha, 410082, China/ College of Civil Engineering, Taiyuan University of Technology, Taiyuan, 030024, China

Yanbin Liu:College of Civil Engineering, Taiyuan University of Technology, Taiyuan, 030024, China

Caijun Shi:College of Civil Engineering, Hunan University, Changsha, 410082, China

Zhipeng Wang:Economic & Technology Research Institute of State Grid Shandong Electric Power Company, Jinan 250021, China

Qi Guo:College of Civil Engineering, Taiyuan University of Technology, Taiyuan, 030024, China

Jinfeng Jiao:College of Civil Engineering, Taiyuan University of Technology, Taiyuan, 030024, China

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