Techno Press
Tp_Editing System.E (TES.E)
Login Search


scs
 
CONTENTS
Volume 36, Number 3, August10 2020
 

Abstract
In this work, a novel three-dimensional model in the generalized thermoelasticity for a homogeneous an isotropic medium was investigated with diffusion, under the effect of thermal loading due to laser pulse in the context of Green-Lindsay theory was investigated. The normal mode analysis technique is used to solve the resulting non-dimensional equations of the problem. Numerical results for the displacement, the thermal stress, the strain, the temperature, the mass concentration, and the chemical potential distributions are represented graphically to display the effect of the thermal loading due to laser pulse and the relaxation time on the resulting quantities. Comparisons are made within the theory in the presence and absence of laser pulse.

Key Words
generalized thermoelasticity; 3-D modeling; laser pulse; diffusion; G-L theory

Address
Mohamed I.A. Othman: Department of Mathematics, Faculty of Science, Zagazig University, P.O. Box 44519, Zagazig, Egypt
Sarhan Y. Atwa: Department of Engineering Mathematics and Physics, Higher Institute of Engineering, Shorouk Academy, Cairo, Egypt

Abstract
A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

Key Words
Precast concrete-encased steel beam; shear capacity; hogging bending moment; sagging bending moment; experimental study; truss-arch model

Address
Yunlong Yu and Yong Yang: School of Civil Engineering, Xi\'an University of Architecture & Technology, Shaanxi, China;
Key Lab of Structural Engineering and Earthquake Resistance, Ministry of Education, China
Yicong Xue: School of Civil Engineering, Xi\'an University of Architecture & Technology, Shaanxi, China
Yaping Liu: China Qiyuan Engineering Corporation, Shaanxi, China



Abstract
Two-storey X-bracings are currently very popular in European practice, as respect to chevron and simple X bracings, owing to the advantages of reducing the bending demand in the brace-intercepted beams in V and inverted-V configurations and optimizing the design of gusset plate connections. However, rules for two-storey X braced frames are not clearly specified within current version of EN1998-1, thus leading to different interpretations of the code by designers. The research presented in this paper is addressed at investigating the seismic behaviour of two-storey X concentrically braced frames in order to revise the design rules within EN1998-1. Therefore, five different design criteria are discussed, and their effectiveness is investigated. With this aim, a comprehensive numerical parametric study is carried out considering a set of planar frames extracted from a set of structural archetypes that are representative of regular low, medium and high-rise buildings. The obtained results show that the proposed design criteria ensure satisfactory seismic performance.

Key Words
concentrically braced frames; two-storey CBF, eurocode 8; capacity design; bracings; seismic design

Address
Silvia Costanzo, Mario D\'Aniello and Raffaele Landolfo: Department of Structures for Engineering and Architecture, University of Naples

Abstract
This article presented a nanoscale modified continuum model to investigate the free vibration of functionally graded (FG) porous nanobeam by using finite element method. The main novelty of this manuscript is presenting effects of four different porosity models on vibration behaviors of nonlocal nanobeam structure including size effect, that not be discussed before The proposed porosity models are, uniform porosity distribution, symmetric with mid-plane, bottom surface distribution and top surface distribution. The nano-scale effect is included in modified model by using the differential nonlocal continuum theory of Eringen that adding the length scale into the constitutive equations as a material parameter constant. The graded material is distributed through the beam thickness by a generalized power law function. The beam is simply supported, and it is assumed to be thin. Therefore, the kinematic assumptions of Euler-Bernoulli beam theory are held. The mathematical model is solved numerically using the finite element method. Results demonstrate effects of porosity type, material gradation, and nanoscale parameters on the free vibration of nanobeam. The proposed model is effective in vibration analysis of NEMS structure manufactured by porous functionally graded materials.

Key Words
free vibration; functionally graded nanobeam; porosity models; nonlocal elasticity theory; finite element method

Address
Emad E. Ghandourh: Nuclear Engineering Dept., Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia
Azza M. Abdraboh: Physics Department, Faculty of Science, Banha University, Banha, Egypt

Abstract
The upper chords in half-through truss bridges are prone to buckling due to a lack of the upper transverse connections. Taking into account geometric and material nonlinearity, nonlinear finite-element analysis of a simple supported truss bridge was carried out to exhibit effects of different types of initial imperfections. A half-wave of initial imperfection was proved to be effective in the nonlinear buckling analysis. And a parameter analysis of initial imperfections was also conducted to reveal that the upper chords have the greatest impact on the buckling, followed by the bottom chords, vertical and diagonal web members. Yet initial imperfections of transverse beams have almost no effect on the buckling. Moreover, using influence surface method, the combinatorial effects of initial imperfections were compared to demonstrate that initial imperfections of the upper chords play a leading role. Furthermore, the equivalent effective length coefficients of the upper chord were derived to be 0.2~ 0.28 by different methods, which implies vertical and diagonal web members still provide effective constraints for the upper chord despite a lack of the upper transverse connections between the two upper chords. Therefore, the geometrical and material nonlinear finite-element method is effective in the buckling analysis due to its higher precision. Based on nonlinear analysis and installation deviations of members, initial imperfection of l/500 is recommended in the nonlinear analysis of half-through truss bridges without initial imperfection investigation.

Key Words
half-through truss bridge; aluminum alloy bridge; stability; nonlinear; influence surface

Address
Wen Qingjie, Yue Zixiang and Liu Zhijun: State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering,
China University of Mining & Technology, 1 Daxue Road, Xuzhou, Jiangsu province, China


Abstract
Contemporary design and construction of steel-concrete composite structures employs the use of prefabricated concrete elements and demountable shear connectors in order to reduce the construction time and costs and enable dismantling of elements for their potential reuse at the end of life of buildings. Bolted shear connector with mechanical coupler is presented in this paper. The connector is assembled from mechanical coupler and rebar anchor, embedded in concrete, and steel bolt, used for connecting steel to concrete members. The behaviour and ultimate resistance of bolted connector with mechanical coupler in wide and narrow members were analysed based on push-out tests and FE analyses conducted in Abaqus software, with focus on concrete edge breakout and bolt shear failure modes. The effect of concrete strength, concrete edge distance and diameter and strength of bolts on failure modes and shear resistance was analysed. It was demonstrated that premature failure by breakout of concrete edge occurs when connectors are located 100 mm or closer from the edge in low-strength and normal-strength reinforced concrete. Furthermore, the paper presents a relatively simple model for hand calculation of concrete edge breakout resistance when bolted connectors with mechanical coupler are used. The model is based on the modification of prediction model used for cast-in and post-installed anchors loaded parallel to the edge, by implementing equivalent influence length of connector with variable diameter. Good agreement with test and FE results was obtained, thus confirming the validity of the proposed method.

Key Words
steel-concrete composite structures; shear connectors; mechanical couplers; shear resistance; concrete edge breakout resistance; finite element analysis

Address
Ivan Milićević, Branko Milosavljević and Milan Spremić: Faculty of Civil Enginering, Univercity of Belgrade, Bulevar kralja Aleksandra 73, 11000 Belgrade, Serbia
Marko Pavlović : Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, Delft, CD, Netherlands

Abstract
This study investigates the seismic performance of steel reinforced concrete (SRC) T-shaped columns under low cyclic loading tests. Based on test results of ten half-scale column specimens, failure patterns, hysteretic behavior, skeleton curves, ultimate strength, ductility, stiffness degradation and energy dissipation capacity were analyzed. The main variables included loading angles, axial compression ratios and steel ratios. The test results show that the average values of the ductility factor and the equivalent viscous damping coefficient with respect to the failure of the columns were 5.23 and 0.373, respectively, reflecting good seismic performance. The ductility decreased and the initial stiffness increased as the axial compression ratio of the columns increased. The strength increased with increasing steel ratio, as expected. The columns displaced along the web had higher strength and initial stiffness, while the columns displaced along the flange had better ductility and energy dissipation capacity. Based on the test and analysis results, a formula is proposed to calculate the effective stiffness of SRC T-shaped columns.

Key Words
steel reinforced concrete; T-shaped column; seismic performance; cyclic loading; effective stiffness

Address
Zuqiang Liu and Jianyang Xue: School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an 710055, China
Key Lab of Structural Engineering and Earthquake Resistance, Ministry of Education (XAUAT), Xi\'an 710055, China
Chaofeng Zhou: School of Civil Engineering, Xi\'an University of Architecture and Technology, Xi\'an 710055, China;
Henan University of Technology, Zhengzhou 450001, China
Roberto T. Leon: Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg 24060, USA




Abstract
The current work, present dynamic analysis of the FG-sandwich plate seated on elastic foundation with various kinds of support using refined shear deformation theory. The present analytical model is simplified which the unknowns number are reduced. The zero-shear stresses at the free surfaces of the FG-sandwich plate are ensured without introducing any correction factors. The four equations of motion are determined via Hamilton\' principle and solved by Galerkin\'s approach for FG-sandwich plate with three kinds of the support. The proposed analytical model is verified by comparing the results with those obtained by other theories existing in the literature. The parametric studies are presented to detect the various parameters influencing the fundamental frequencies of the symmetric and non-symmetric FG-sandwich plate with various boundary conditions.

Key Words
dynamic analysis, FG-sandwich plates; RPT model; Galerkin

Address
Abderrahmane Menasria: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria ;
Université de Abbés Laghrour Khenchela, Faculté de Sciences & Technologie, Département de Génie Civil, Algeria
Abdelhakim Kaci: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
Université Dr Tahar Moulay, Faculté de Technologie, Département de Génie Civil et Hydraulique, BP 138 Cité En-Nasr 20000 Saida, Algérie
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Département de Physique, Faculté des Sciences Exactes, Département de Physique, Université de Sidi Bel Abbés, Algeria;
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
Fouad Bourada: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia;
Département des Sciences et de la Technologie, centre universitaire de Tissemsilt, BP 38004 Ben Hamouda, Algérie
Abdeldjebbar Tounsi, Kouider Halim Benrahou and
Abdelouahed Tounsi: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
E.A. Adda Bedia: Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
S.R. Mahmoud: GRC Department, Jeddah Community College, King Abdulaziz University, Jeddah, Saudi Arabia










Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2020 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-42-828-7996, Fax : +82-2-736-6801, Email: info@techno-press.com