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CONTENTS
Volume 80, Number 1, October10 2021
 


Abstract
This paper presents the stress analysis of a composite laminated simply supported plate with porosity under hygrothermal rising. In the displacement-strain relation of the plate structure, the first shear plate deformation theory is used. Material properties of laminas are considered as orthotropic. Three different porosity distributions are used. In the solution process, the Navier method is implemented for simply supported laminated composite plate. Non-uniform temperature and moisture rising are considered for laminated plate with three laminas. In the numerical results, the stress distributions of the laminated plate are presented and discussed for different values of moisture, temperature, stacking sequence of laminas and orientation angle of layers. The numerical results show that the hygrothermal condition is very effective in the stress behavior of laminated plates.

Key Words
first shear plate deformation theory; hygro-thermal effect; laminated plates; porosity; stress analysis

Address
Y.Z. Yüksel and Ş.D. Akbaş: Department of Civil Engineering, Bursa Technical University, 16330, Bursa, Turkey

Abstract
This paper aims to provide a comprehensive performance assessment of a latticed tension-type transmission tower by performing both full-scale static tests and numerical simulations. In particular, a full-scale tension-type transmission tower was firstly constructed and tested for examining the performances under design loads and the ultimate capacity under an extreme wind load. The displacement and strain responses are investigated, and the failure process of the tension-type tower is presented. Numerical simulations are then performed in order to capture the failure process and estimate the bearing capacity of the experimental tower under the overload case. Moreover, Numerical simulations are also adopted to evaluate the influence of wind attack angles on the structural behavior of the tested tower. Experimental and numerical results demonstrate that this latticed tension-type transmission tower is designed with sufficient capacity to resist the design loads, and the buckling failures of the leg members at the bottom are the governing reason for the collapse of tower. In addition, the developed numerical model can accurately present the failure and structural response of the tension-type tower, and the influence of wind attack angles on the structural behavior is significant. This research is beneficial for improving the understanding on the bearing capacity and design of latticed tension-type transmission towers.

Key Words
full-scale test; numerical simulation; latticed tension-type transmission tower; ultimate capacity; buckling failures; wind attack angle

Address
Juncai Liu, Li Tian, Ruisheng Ma: School of Civil Engineering, Shandong University, Jinan, Shandong Province 250061, PR China
Bin Zhang: Power China Henan Electric Power Survey & Design Institute Co., Ltd, Zhengzhou, 450000, Henan, PR China
Aiqiang Xin: School of Civil Engineering, Shandong University, Jinan, Shandong Province 250061, PR China

Abstract
Shell bridges have attracted extensive interest in engineering research and practice. This paper aims to evaluate the effects of longitudinal and transverse curvatures on the optimal design of the shell bridge. For this purpose, a slant-legged steel shell footbridge with the same initial and target volumes of steel was chosen to build parametric geometric models with different curvature radii, and then topology optimization was carried out using the bi-directional evolutionary structural optimization (BESO) technique to obtain optimized designs with high structural stiffness. Furthermore, linear static analysis and eigenvalue analysis demonstrate that the displacement, von Mises effective stress, and the first-order vertical vibration frequency satisfied all the requirements of design regulations. Numerical results indicate that not only the longitudinal curvature but also the transverse curvature have a significant effect on the optimized designs of steel shell footbridge. While the mean compliance increased with the transverse curvature radius, it first decreased and then increased with the longitudinal curvature radius.

Key Words
BESO method; curvature radius; optimal design; shell bridge; steel shell; topology optimization

Address
Shiming Liu: School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450045, China; Centre for Innovative Structures and Materials, School of Engineering, RMIT University, Melbourne 3001, Australia; International Joint Research Lab for Eco-building Materials and Engineering of Henan Province, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Bin Huang: School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
Yi Min Xie: Centre for Innovative Structures and Materials, School of Engineering, RMIT University, Melbourne 3001, Australia

Abstract
A general approach is presented for the free vibration analysis of circular cylindrical shell resting on elastic foundation and subjected to classical boundary conditions of any type. The Winkler/Pasternak model is utilized to simulate the elastic foundation imposed on the cylindrical shell, and then it is easily to derive the potential energy of the elastic foundation. Based on the Flügge shell theory, explicit expressions for the mass and stiffness matrices are obtained. By taking the characteristic beam modal functions as the admissible functions, the Rayleigh-Ritz method is employed to derive the frequency equations of circular cylindrical shell with all the classical boundary conditions and resting on elastic foundation. Once the frequency equation has been determined, the frequencies can be calculated numerically. The excellent accuracy and validity of the present approach are demonstrated by numerical examples and comparisons with the results available in the literature. Finally, some further numerical results are given to illustrate the comprehensive effect of geometric properties and foundation coefficients on the frequencies of circular cylindrical shell in contact with elastic foundation.

Key Words
circular cylindrical shell; elastic foundation; free vibration; Rayleigh-Ritz method

Address
Jinsong Yang: School of Traffic and Transportation Engineering, Central South University, Changsha 410075, PR China
Jianbin Cao: School of Mechatronic Engineering, Jiangsu Normal University, Xuzhou 221116, PR China
Jingsong Xie: School of Traffic and Transportation Engineering, Central South University, Changsha 410075, PR China
Haixiao Zhao: School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, PR China

Abstract
This experimental study aims to investigate the properties of sand concrete (SC) by using sisal fibres and latex in various fields in construction. Sisal fibres were applied at four ratios of 0.05%, 0.10%, 0.15% and 0.20%, while liquid latex was replaced with three ratios of 15%, 25% and 35%. In this context, ideal percentages of sisal fibre (0.1% F) and latex (35% L) were combined in a single cement matrix. For each percentage, tests on flow, density, compressive strength, flexural strength, ultrasonic pulse velocity, modulus of elasticity, water accessible porosity, water absorption and shrinkage were performed on fresh and hardened SC. Scanning electron microscopy (SEM) was also conducted for microstructure analysis. Results indicate that adding latex emulsion to SC containing sisal fibres increased the adhesion of the fibres to the cement matrix, which contributed to the increase in flexural strength and the decrease in shrinkage. This condition also helped reduce the porosity and water absorption of latex-modified SC with sisal fibres compared with SC that contained fibres. The improvement occurred in the properties that constitute an obstacle to the widespread use of SC. Thus this improvement has practical implications.

Key Words
durability; liquid latex; mechanical properties; microstructural behavior; sand concrete; sisal

Address
Oday Z. Jaradat, Karima Gadri: Laboratory of Research in Civil Engineering, Mohamed Khider University of Biskra, Algeria
Bassam A. Tayeh: Civil Engineering Department, Faculty of Engineering, Islamic University of Gaza, Palestine
Abdelhamid Guettalaa: Laboratory of Research in Civil Engineering, Mohamed Khider University of Biskra, Algeria

Abstract
The snap buckling of the FG curved pipes conveying fluid has not been reported due to the existing research on the snap-buckling problem. Therefore, the purpose of this paper is to explore this issue. First, we adopt a new high-order shear theory model and consider the thermal and geometric nonlinearity effects, and assume that the density and modulus of elasticity of the liquid are independent of temperature. Based on the generalized variational principle, the governing equation of the FG curved pipes conveying fluid is derived. Then, we assume that the FG curved pipes conveying fluid has simply supported boundary or fixed supported boundary conditions, and use the two step perturbation method to obtain the expression of the relationship between load and deflection. Then, we investigate the influence of boundary conditions, shear deformation, temperature variation, functional gradient index parameters, liquid flow velocity and geometry size on the snap buckling problems of the FG curved pipes conveying fluid. The results show that these factors have significant influence on the fluidstructure interaction problems.

Key Words
a higher-order shear beam model; conveying-fluid pipes; functionally graded materials; snap-buckling

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

Abstract
This paper presents a three-dimensional analysis of tall building structures using an improved continuous medium technique model in which consistent global column bending and column longitudinal deformation are considered along with a decoupling technique for the resulting system of differential equations. A numerical example shows that although the proposed methodology is very simple and suitable for hand calculations, it presents very good accuracy in comparison with finite element method computations.

Key Words
buildings; frames; simulation; static analysis; structural design

Address
José E. Laier: Department of Structural Engineering, Engineering School of São Carlos, University of São Paulo, Av. Trabalhador Sãocarlense 400, 13566-590 São Carlos, SP, Brazil

Abstract
In this paper, the effects of different replacement levels of halloysite nanotube (HNT), colloidal nano-silica (CS), micro-silica (MS), and the combination of them on the fresh and hardened properties of self-compacting lightweight concrete (SCLC) are studied. Four factors including water to binder ratio (w/b) with two levels of 0.35 and 0.45, CS with three replacement levels of 1, 3 and 5%, MS with the replacement level of 10% and HNT with three replacement levels of 1, 2 and 3% were chosen. The fresh properties of SCLCs were observed in terms of slump flow diameter and time, J-ring diameter, Vfunnel time and U-box tests. The hardened properties were determined through mechanical properties including compressive strength, tensile strength, modulus of elasticity and flexural strength. The non-destructive tests including electrical resistivity and water absorption were executed too. Moreover, the effects of MS, CS and HNT contents on the fracture energy of SCLC samples were studied. The results displayed that the mentioned properties for the SCLC specimens containingMS, CS and HNT improved, but the superior performance was obtained in binary mixes, which were created by adding both MS and CS simultaneously. The optimal conditions for having the best results were obtained when the amounts of MS and CS were 10% and 3%, respectively.

Key Words
colloidal nano-silica; micro-silica; halloysite nanotube; self-compacting lightweight concrete

Address
Moosa Mazloom: Department of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran
Pardis Pourhaji: Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
Oveys Afzali-Naniz: Department of Civil Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran

Abstract
This study presents topology optimization of plate structures by employing isogeometrical level set method. For structural analysis of plates, the IsoGeometric Analysis (IGA) approach is applied and Non-Uniform Rational B-Splines (NURBS) basis functions are used for approximation of the design domain geometry as well as the unknown deformation field. In this paper, the level set function is parametrized with Radial Basis Functions (RBFs), which is more efficient than the conventional level set method. This approach along with an approximate re-initialization scheme can maintain a smooth level set function during the optimization process and has less dependency on initial designs because of its ability to nucleate new holes inside the design domain. Due to capability of IGA method in modeling complex design domains while maintaining high accuracy in analysis, combination of IGA with RBFs level set method provides a very useful and effective technique for topology optimization problems. Several numerical examples are prepared to demonstrate the efficiency and accuracy of the method and obtained optimum topologies are compared with the results of other methods in literature.

Key Words
isogeometric analysis; level set method; radial basis functions; topology optimization of plates

Address
A. Halaku and S.M. Tavakkoli: Civil Engineering Department, Shahrood University of Technology, Shahrood, Iran


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