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CONTENTS
Volume 31, Number 4, May25 2019
 

Abstract
An innovated type of the flat steel plate-lightweight aggregate concrete hollow composite slab was presented in this paper. This kind of the slab is composed of flat steel plate and the lightweight aggregate concrete slab, which were interfaced with a set of perfobond shear connectors (PBL shear connectors) with circular hollow structural sections (CHSS) and the shear stud connectors. Five specimens were tested under static monotonic loading. In the test, the influence of shear span/height ratios and arrangements of CHSS on bending capacity and flexural rigidity of the composite slabs were investigated. Based on the test results, the crack patterns, failure modes, the bending moment-curvature curves as well as the strains of the flat steel plate and the concrete were focused and analyzed. The test results showed that the flat steel plate was fully connected to the lightweight aggregate concrete slab and no obvious slippage was observed between the steel plate and the concrete, and the composite slabs performed well in terms of bending capacity, flexural rigidity and ductility. It was further shown that all of the specimens failed in bending failure mode regardless of the shear span/height ratios and the arrangement of CHSS. Moreover, the plane-section assumption was proved to be valid, and the calculated formulas for predicting the bending capacity and the flexural rigidity of the composite slabs were proposed on the basis of the experimental results.

Key Words
steel plate-concrete hollow composite slab; mechanical behavior; bending capacity; flexural rigidity; static test

Address
School of Civil Engineering, Xi\'an University of Architecture & Technology, Xi\'an, Shaanxi 710055, China.


Abstract
Non-monolithic concrete structural connections are commonly used both in new constructions and retrofitted structures where anchors are used for connections. Often, flaws are present in anchor system due to poor workmanship and deterioration; and methods available to check the quality of the composite system afterward are very limited. In case of presence of flaw, load transfer mechanism inside the anchor system is severely disturbed, and the load carrying capacity drops drastically. This raises the question of safety of the entire structural system. The present study proposes a wave propagation technique to assess the integrity of the anchor system. A chemical anchor (embedded in concrete) composite system comprising of three materials viz., steel (anchor), polymer (adhesive) and concrete (base) is considered for carrying out the wave propagation studies. Piezoelectric transducers (PZTs) affixed to the anchor head is used for actuation and the PZTs affixed to the surrounding concrete surface of the concrete-anchor system are used for sensing the propagated wave through the anchor interface to concrete. Experimentally validated finite element model is used to investigate three types of composite chemical anchor systems. Studies on the influence of geometry, material properties of the medium and their distribution, and the flaw types on the wave signals are carried out. Temporal energy of through time domain differentiation is found as a promising technique for identifying the flaws in the multi-layered composite system. The present study shows a unique procedure for monitoring of inaccessible but crucial locations of structures by using wave signals without baseline information.

Key Words
steel-polymer-concrete composite; chemical anchor; damage detection; ultrasonic wave propagation; Piezoelectric transducers (PZTs); temporal energy; numerical simulations

Address
(1) Rajanikant Rao:
Academy of Scientific and Innovative Research (AcSIR), India;
(2) Rajanikant Rao, Saptarshi Sasmal:
Special and Multifunctional Structures Laboratory, CSIR-Structural Engineering Research Centre, Taramani, Chennai-600113, India.

Abstract
In recent years, considerable attention has been paid to the research and development of high-strength steel plates, with particular emphasis on the enhancement of the seismic resistance of buildings and bridges. Many efforts have also been undertaken to improve the properties of high-strength bolts and weld materials. However, there are still different opinions on steel joints that combine high-strength bolts and fillet welds. Therefore, it is necessary to verify the design specifications and guidelines, especially for newly developed 1,400-MPa high-strength bolts, 570-MPa steel plates, and weld materials. This paper presents the results of literature reviews and experimental investigations. Test parameters include bolt strengths, weld orientations, and their combinations. The results show that advances in steel materials have increased the plastic deformation capacities of steel welds. That allows combination joints to gain their maximum strength before the welds have fracture failures. When in combination with longitudinal welds, high-strength bolts slip, come in contact with cover plates, and develop greater bearing strength before the joints reach their maximum strength. However, in the case of combinations with transverse welds, changes in crack angles cause the welds to provide additional strength. The combination joints can therefore develop strength greater than estimated by adding the strength of bolted joints in proportion to those of welded joints. Consequently, using the slip resistance as the available strength of high-strength bolts is recommended. That ensures a margin of safety in the strength design of combination joints.

Key Words
combination joints; high-strength bolts; slip and bearing conditions; fillet welds; crack angles

Address
(1) Heui-Yung Chang:
Department of Civil and Environmental Engineering, National University of Kaohsiung, 700, Kaohsiung University Rd., Kaohsiung 811, Taiwan;
(2) Ching-Yu Yeh:
Department of Civil Engineering, National Cheng Kung University,1, University Rd., Tainan 701, Taiwan.

Abstract
This paper presents a useful in-plane structural analysis of low-rise blind-bolted composite frames with semi-rigid joints. Analytical models were used to predict the moment-rotation relationship of the composite beam-to-column flush endplate joints that produced accurate and reliable results. The comparisons of the analytical model with test results in terms of the moment-rotation response verified the robustness and reliability of the model. Abaqus software was adopted to conduct frame analysis considering the material and geometrical non-linearities. The flexural behaviour of the composite frames was studied by applying the lateral loads incorporating wind and earthquake actions according to the Australian standards. A wide variety of frames with a varied number of bays and storeys was analysed to determine the bending moment envelopes under different load combinations. The design models were finalized that met the strength and serviceability limit state criteria. The results from the frame analysis suggest that among lateral loads, wind loads are more critical in Australia as compared to the earthquake loads. However, gravity loads alone govern the design as maximum sagging and hogging moments in the frames are produced as a result of the load combination with dead and live loads alone. This study provides a preliminary analysis and general understanding of the behaviour of low rise, semi-continuous frames subjected to lateral load characteristics of wind and earthquake conditions in Australia that can be applied in engineering practice.

Key Words
composite frames; beam-to-column joints; initial stiffness; moment capacity; moment-rotation relationship; lateral loads; frame analysis; semi-rigid connection

Address
(1) Rumman Waqas:
School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia;
(2) Brian Uy, Jia Wang:
School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia;
(3) Huu-Tai Thai:
Department of Infrastructure Engineering, The University of Melbourne, Parkville, VIC 3010, Australia.

Abstract
This paper deals with the effect of ply orientation and control gain on tip transverse displacement of functionally graded beam layer for both active constrained layer damping (ACLD) and passive constrained layer damping (PCLD) system. The functionally graded beam is taken as host beam with a bonded viscoelastic layer in ACLD beam system. Piezoelectric fiber reinforced composite (PFRC) laminate is a constraining layer which acts as actuator through the velocity feedback control system. A finite element model has been developed to study actuation of the smart beam system. Fractional order derivative constitutive model is used for the viscoelastic constitutive equation. The control voltage required for ACLD treatment for various symmetric ply stacking sequences is highest in case of longitudinal orientation of fibers of PFRC laminate over other ply stacking sequences. Performance of symmetric and anti-symmetric ply laminates on damping characteristics has been investigated for smart beam system using time and frequency response plots. Symmetric and anti-symmetric ply laminates significantly reduce the amplitude of the vibration over the longitudinal orientation of fibers of PFRC laminate. The analysis reveals that the PFRC laminate can be used effectively for developing very light weight smart structures.

Key Words
finite element model; control gain; ACLD; PCLD; functionally graded beam; PFRC

Address
(1) Ravindra Singh Chahar:
Department of Aeronautical Engineering, Manav Rachna International Institute of Research & Studies, Faridabad, Haryana 121002, India;
(2) Ravi Kumar B.:
School of Mechanical Engineering, SASTRA Deemed University, Thanjavur, Tamilnadu 613402, India.

Abstract
In this paper, a geometrically nonlinear meshfree analysis of 3D various forms of shell structures using the double director shell theory with finite rotations is proposed. This theory is introduced in the present method to remove the shear correction factor and to improve the accuracy of transverse shear stresses with the consideration of rotational degrees of freedom.The present meshfree method is based on the radial point interpolation method (RPIM) which is employed for the construction of shape functions for a set of nodes distributed in a problem domain. Discrete system of geometrically nonlinear equilibrium equations solved with the Newton-Raphson method is obtained by incorporating these interpolations into the weak form. The accuracy of the proposed method is examined by comparing the present results with the accurate ones available in the literature and good agreements are found.

Key Words
meshfree method; geometric nonlinear analysis; 3D shell structures; double directors shell theory; finite rotations; RPIM

Address
(1) Monther Wali:
Department of Mechanical Engineering, College of Engineering, King Khalid University, Abha, Saudi Arabia;
(2) Hana Mellouli, Hanen Jrad, Monther Wali, Fakhreddine Dammak:
Laboratory of Electromechanical Systems (LASEM), National Engineering School of Sfax, University of Sfax, Route de Soukra km 4, 3038 Sfax, Tunisia.

Abstract
The choice of individual material for industrial application is primarily based on knowledge of its behavior in similar applications and similar environmental conditions. Contemporary design implies knowledge of material behavior and knowledge in the area of structural analysis supported by large capacity computers. Bearing this in mind, this paper presents and analyzes the experimental results related to the mechanical properties of the material considered (30CrNiMo8/1.6580/AISI 4340) at different temperatures as well as its creep and fatigue behavior. All experimental tests were carried out as uniaxial tests. The test results related to the mechanical properties are presented in the form of engineering stress-strain diagrams. The results related to the creep behavior of the material are shown in the form of creep curves, while the fatigue of the material is shown in the form of stress – life (SN) diagram. Based on these experimental results, the values of the following properties are determined: ultimate tensile strength (σm,20 = 696 MPa), yield strength (σ0.2,20 = 355.5 MPa), modulus of elasticity (E,20 = 217 GPa) and fatigue limit (σf,20,R = 280.4 MPa). Results related to fatigue tests were obtained at room temperature and stress ratio R = -1.

Key Words
steel 30CrNiMo8; fatigue; creep; mechanical properties; Charpy impact energy

Address
(1) Josip Brnic, Marino Brcic, Sanjin Krscanski, Domagoj Lanc:
Department of Engineering Mechanics, University of Rijeka, Faculty of Engineering, Vukovarska 58, Croatia;
(2) Sijie Chen:
School of Material Science and Engineering, Henan Polytechnic University, 2001 Century Avenue, Jiaozuo 454003, P.R. China.

Abstract
In this paper, buckling analyses of composite plate reinforced by Graphen platelate (GPL) is studied. The Halphin- Tsai model is used for obtaining the effective material properties of nano composite plate. The nano composite plate is modeled by Third order shear deformation theory (TSDT). The elastic medium is simulated by Winkler model. Employing nonlinear strains-displacements, stress-strain, the energy equations of plate are obtained and using Hamilton's principal, the governing equations are derived. The governing equations are solved based on Navier method. The effect of GPL volume percent, geometrical parameters of plate and elastic foundation on the buckling load are investigated. Results showed that with increasing GPLs volume percent, the buckling load increases.

Key Words
buckling; nanocomposite plate; Graphen platelate; Reddy theory; Halphin-Tsai model

Address
Department of Civil Engineering, Jasb Branch, Islamic Azad University, Jasb, Iran.



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