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CONTENTS
Volume 46, Number 4, February25 2023
 

Abstract
The use of precast hollow-core slabs (PCHCS) in civil construction has been increasing due to the speed of execution and reduction in the weight of flooring systems. However, in the literature there are no studies that present a finite element model (FEM) to predict the load-slip relationship behavior of pushout tests, considering headed stud shear connector and PCHCS placed at the upper flange of the downstand steel profile. Thus, the present paper aims to develop a FEM, which is based on tests to fill this gap. For this task, geometrical non-linear analyses are carried out in the ABAQUS software. The FEM is calibrated by sensitivity analyses, considering different types of analysis, the friction coefficient at the steel-concrete interface, as well as the constitutive model of the headed stud shear connector. Subsequently, a parametric study is performed to assess the influence of the number of connector lines, type of filling and height of the PCHCS. The results are compared with analytical models that predict the headed stud resistance. In total, 158 finite element models are processed. It was concluded that the dynamic implicit analysis (quasi-static) showed better convergence of the equilibrium trajectory when compared to the static analysis, such as arc-length method. The friction coefficient value of 0.5 was indicated to predict the load-slip relationship behavior of all models investigated. The headed stud shear connector rupture was verified for the constitutive model capable of representing the fracture in the stress-strain relationship. Regarding the number of connector lines, there was an average increase of 108% in the resistance of the structure for models with two lines of connectors compared to the use of only one. The type of filling of the hollow core slab that presented the best results was the partial filling. Finally, the greater the height of the PCHCS, the greater the resistance of the headed stud.

Key Words
concrete topping; finite element model; headed stud; PCHCS; pushout

Address
Lucas Mognon Santiago Prates:Department of Civil Engineering, State University of Maringá, Av. Colombo n

Abstract
This paper presents an analytical hyperbolic theory based on the refined shear deformation theory for mechanical stability analysis of the simply supported advanced composites plates (exponentially, sigmoidal and power-law graded) under triangular, trapezoidal and uniform uniaxial and biaxial loading. The developed model ensures the boundary condition of the zero transverse stresses at the top and bottom surfaces without using the correction factor as first order shear deformation theory. The mathematical formulation of displacement contains only four unknowns in which the transverse deflection is divided to shear and bending components. The current study includes the effect of the geometric imperfection of the material. The modeling of the micro-void presence in the structure is based on the both true and apparent density formulas in which the porosity will be dense in the mid-plane and zero in the upper and lower surfaces (free surface) according to a logarithmic function. The analytical solutions of the uniaxial and biaxial critical buckling load are determined by solving the differential equilibrium equations of the system with the help of the Navier's method. The correctness and the effectiveness of the proposed HyRPT is confirmed by comparing the results with those found in the open literature which shows the high performance of this model to predict the stability characteristics of the FG structures employed in various fields. Several parametric analyses are performed to extract the most influenced parameters on the mechanical stability of this type of advanced composites plates.

Key Words
hyperbolic theory; mechanical stability; advanced composites plates; porosity; Navier's method

Address
S.R. Mahmoud: GRC Department, Applied College, King Abdulaziz University, Jeddah, Saudi Arabia

E.I. Ghandourah: Department of Nuclear Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia

A.H. Algarni: Statistics Department, Faculty of Science, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia

M.A. Balubaid: Department of Industrial Engineering, Faculty of Engineering, King Abdulaziz University, Jeddah, Saudi Arabia

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 3)Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria

Abdeldjebbar Tounsi: Industrial Engineering and Sustainable Development Laboratory, University of Relizane, Faculty of Science & Technology, Mechanical Engineering Department, Algeria

Fouad Bourada: 1)Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria 2) Science and Technology Department, Faculty of Science and Technology, Tissemsilt University, Algeria


Abstract
Bending static and stress investigation of a microplate of piezoelectric/piezomagnetic material subjected to combined multifield loading. Shear deformable as well as thickness stretched model is used for derivation of the kinematic relations. Multi field governing equations are derived analytically through principle of virtual work. the results are analytically obtained analytically including magnetic/electric potentials, displacement and stress components with variation in multifield loading parameters.

Key Words
deflection and stress analysis; higher-order model; sandwich piezoelectric/piezomagnetic microplate; smalldependent; virtual work principl

Address
Xiaoping Zou:Sichuan Jinghengxin Construction Engineering Testing Co., Ltd, Luzhou 646000, China

Gongxing Yan:1)School of Intelligent Construction, Luzhou vocational and technical college, Luzhou 646000, China
2)Luzhou Key Laboratory of Intelligent Construction and Low-carbon Technology, Luzhou 646000, China

Wangming Wu:Aneng Third Bureau Chengdu Engineering Quality Testing Co., Ltd, Chengdu 611130, China

Wenjie Yang:Sichuan Jinghengxin Construction Engineering Testing Co., Ltd, Luzhou 646000, China

Weiwei Shi and Yuhusun Sun:Aneng Third Bureau Chengdu Engineering Quality Testing Co., Ltd, Chengdu 611130, China

Abstract
Using light weight concrete as infill material in conventional cold-formed steel (CFS) shear wall systems can considerably increase their load bearing capacity, ductility, integrity and fire resistance. The compressive strength of the filler concrete is a key factor affecting the structural behaviour of the composite wall systems, and therefore, achieving maximum compressive strength in lightweight concrete while maintaining its lightweight properties is of significant importance. In this study a new type of optimum polystyrene lightweight concrete (OPLC) with high compressive strength is developed for infill material in composite CFS shear wall systems. To study the seismic behaviour of the OPLC-filled CFS shear wall systems, two full scale wall specimens are tested under cyclic loading condition. The effects of OPLC on load-bearing capacity, failure mode, ductility, energy dissipation capacity, and stiffness degradation of the walls are investigated. It is shown that the use of OPLC as infill in CFS shear walls can considerably improve their seismic performance by: (i) preventing the premature buckling of the stud members, and (ii) changing the dominant failure mode from brittle to ductile thanks to the bond-slip behaviour between OPLC and CFS studs. It is also shown that the design equations proposed by EC8 and ACI 318-14 standards overestimate the shear force capacity of OPLC-filled CFS shear wall systems by up to 80%. This shows it is necessary to propose methods with higher efficiency to predict the capacity of these systems for practical applications.

Key Words
cold formed steel frame; composite wall system; cyclic behaviour; Optimum Polystyrene Lightweight Concrete (OPLC); seismic performance

Address
Mohammad Rezaeian Pakizeh, Hossein Parastesh:Department of Civil Engineering, University of Science and Culture, Tehran, Iran

Iman Hajirasouliha:Department of Civil and Structural Engineering, The University of Sheffield, Sheffield, UK

Farhang Farahbod:Building and Housing Research Center (BHRC), Tehran, Iran

Abstract
Buckling and post-buckling behaviors of geometrically perfect double-curvature shells made from smart composites have been investigated. The shell has been supposed to be exposed to transverse mechanical loading and magneto-electro-elastic (MEE) coupling. The composite shell has been made of two constituents which are piezoelectric and magnetic ingredients. Thus, the elastic properties might be variable based upon the percentages of the constituents. Incorporating small scale impacts in regard to nonlocal theory leads to the establishment of the governing equations for the double-curvature nanoshell. Such nanoshell stability will be shown to be affected by composite ingredients. More focus has been paid to the effects of small scale factor, electric voltage and magnetic intensity on stability curves of the nanoshell.

Key Words
nonlocal scale; numerical analysis; post-buckling; shell; stability; static response

Address
Zhanlei Wang:College of Civil and Architecture Engineering, Chuzhou University, Chuzhou 239000, Anhui, China

Ye Chen:Shijiazhuang Institute of Railway Technology, Shijiazhuang 050000, Hebei, China

Abstract
This paper focuses on the energy absorption of lattice core sandwich structures of different configurations. The diamond lattice unit cell, which has been extensively investigated for energy absorption applications, is the starting point for this research. The energy absorption behaviour of sandwich structures with an expanded metal sheet as the core is investigated at low-velocity impact loading. Numerical simulations were carried out using ABAQUS/EXPLICIT and the results were thoroughly compared with the experimental results, which indicated desirable accuracy. A parametric analysis, using a BoxBehnken design (BBD), as a method for the design of experiments (DOE), was performed. The samples fabricated in three levels of parameters include 0.081, 0.145, and 0.562 mm2 Cell sizes, and 0, 45, and 90-degree cell orientation, which were investigated. It was observed from experimental data that the angle of cells orientation had the highest degree of influence on the specific energy absorption. The results showed that the angle of cells orientation has been the most influential parameter to increase the peak forces. The results from using the design expert software showed the optimal specific energy absorption and peak force to be 1786 J/kg and 26314.4 N, respectively. The obtained R2 values and normal probability plots indicated a good agreement between the experimental results and those predicted by the model.

Key Words
drop-weight test; energy absorption; lattice sheet; low-velocity impact; sandwich structures

Address
Keramat Malekzadeh Fard:Department of Mechanical Engineering, MalekAshtar University of Technology, Tehran, Iran, P.O.B. 13445768

Meysam Mahmoudi:2Department of Mechanical Engineering, Velayat University, Iranshahr, Iran


Abstract
In order to study the fire resistance of castellated composite beams with ortho-hexagonal holes and different beamend restraints, temperature rise tests with constant load were conducted on full-scale castellated composite beams with orthohexagonal holes and hinge or rigid joint constraints to investigate the temperature distribution, displacement changes and failure patterns of castellated composite beams with two different beam-end constraints during the whole course of fire. The results show that (1) During the fire, the axial pressure and horizontal expansion deformation generated in the rigid joint constrained composite beam were larger than those in the hinge joint constrained castellated composite beam, and their maximum horizontal expansion displacements were 30.2 mm and 17.8 mm, respectively. (2) After the fire, the cracks on the slab surface of the castellated composite beam with rigid joint constraint were more complicated than hinge restraint, and the failure more serious; the lower flange and web at the ends of the castellated steal beams with hinge and rigid joint constraint produced serious local buckling, and the angles of the ortho-hexagonal holes at the support cracked; the welds at both ends of the castellated composite beam with rigid joint constraint cracked. (3) Based on the simplified calculation method of solid-web composite beam, considering the effect of holes on the web, this paper calculated the axial force and displacement of the beam-end constrained castellated composite beams under fire. The calculation results agreed well with the test results.

Key Words
axial force; calculation method; castellated composite beams; different beam-end constraints; fire test; horizontal displacement

Address
Junli Lyu:1)School of Civil Engineering, Shandong Jianzhu University, Jinan, 250101, China
2)Key Lab of Building Structural Retrofitting and Underground Space Engineering, Ministry of Education, Jinan 250101, China

Encong Zhu, Rukai Li, Bai Sun and Zili Wang:School of Civil Engineering, Shandong Jianzhu University, Jinan, 250101, China


Abstract
In the current research, the nonlinear free vibrations of curved pipes made of functionally graded (FG) carbon nanotube reinforced composite (CNTRC) materials are investigated. It is assumed that the FG-CNTRC curved pipe is supported on a three-parameter nonlinear elastic foundation and is subjected to a uniform temperature rise. Properties of the curved nanocomposite pipe are distributed across the radius of the pipe and are given by means of a refined rule of mixtures approach. It is also assumed that all thermomechanical properties of the nanocomposite pipe are temperature-dependent. The governing equations of the curved pipe are obtained using a higher order shear deformation theory, where the traction free boundary conditions are satisfied on the top and bottom surfaces of the pipe. The von Kármán type of geometrical non-linearity is included into the formulation to consider the large deflection in the curved nanocomposite pipe. For the case of nanocomposite curved pipes which are simply supported in flexure and axially immovable, the motion equations are solved using the two-step perturbation technique. The closed-form expressions are provided to obtain the small- and large-amplitude frequencies of FGCNTRC curved pipes rested on a nonlinear elastic foundation in thermal environment. Numerical results are given to explore the effects of CNT distribution pattern, the CNT volume fraction, thermal environment, nonlinear foundation stiffness, and geometrical parameters on the fundamental linear and nonlinear frequencies of the curved nanocomposite pipe.

Key Words
carbon nanotube reinforced composite; curved pipe; nonlinear elastic foundation; nonlinear vibration; thermal environment; two-step perturbation technique

Address
Mingjie Liu:Shaoping Bi, Sicheng Shao:Quzhou College of Technology, Quzhou 324000, China

Hadi Babaei:Department of Mechanical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran

Abstract
This study represents a numerical research in vibration and buckling of functionally graded material (FGM) beam comprising edge crack by using finite element method (FEM) and multilayer perceptron (MLP). It is assumed that the material properties change only according to the exponential distributions along the beam thickness. FEM and MLP solutions of the natural frequencies and critical buckling load are obtained of the cracked FGM beam for clamped–free (C-F), hinged–hinged (H-H), and clamped–clamped (C-C) boundary conditions. Numerical results are obtained to show the effects of crack location (c/L), material properties (E2/E1), slenderness ratio (L/h) and end supports on the bending vibration and buckling properties of cracked FGM beam. The FEM analysis used in this paper was verified with the literature, and the fundamental frequency ratio (w) and critical buckling load ratio (Pcr) results obtained were compared with FEM and MLP. The results obtained are quite compatible with each other.

Key Words
buckling; edge crack; finite element method; functionally graded material; multilayer perceptron; vibration

Address
Murat Yaylaci:Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey

Ecren Uzun Yaylaci:Technology Transfer Office, Recep Tayyip Erdogan University, 53100, Rize, Turkey

Mehmet Emin Ozdemir:Department of Civil Engineering, Cankiri Karatekin University, 18100, Çankiri, Turkey

Şevval Ozturk:Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey

Hasan Sesli:Department of Civil Engineering, Yalova University, 77200, Yalova, Turkey

Abstract
In this study, on-site testing was carried out to investigate the vibration performance of a cold-formed thin-walled steel floor system. Ambient vibration, walking excitation (single and double persons), and impulsive excitation (heel-drop and jumping) were considered to capture the primary vibration parameters (natural frequencies, damping ratios, and mode shapes) and vertical acceleration response. Meanwhile, to discuss the influence of cement fiberboard on structural vibration, the primary vibration parameters were compared between the systems with and without the installation of cement fiberboard. Based on the experimental analysis, the cold-formed thin-walled steel floor possesses high frequency (〉10 Hz) and damping (〉 2%); the installed cement fiberboard mainly increases the mass of floor system without effectively increasing the floor stiffness and may reduce the effects of primary vibration parameters on acceleration response; and the human-structure interaction should be considered when analyzing the vibration serviceability. The comparison of the experimental results with those in the AISC Design Guide indicates that the cold-formed thin-walled steel floor exhibits acceptable vibration serviceability. A crest factor Brp (ratio of peak to root-mean-square accelerations) is proposed to determine the root-mean-square acceleration for convenience.

Key Words
cement fibreboard; cold-formed thin-walled steel floor; human-structure interaction; on-site testing; vibration serviceability

Address
Bin Chen:Chengdu Architectural Design & Research Institute Co., LTD. Chengdu China, 610041

Liang Cao:1)College of Civil Engineering, Hunan University, Changsha 410082, China
2)Key Laboratory for Damage Diagnosis of Engineering Structures of Hunan Province, Hunan University, Changsha 410082, China

Faming Lu:Chengdu Architectural Design & Research Institute Co., LTD. Chengdu China, 610041

Y. Frank Chen:Department of Civil Engineering, The Pennsylvania State University, Middletown, PA, 17057, USA

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