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CONTENTS
Volume 39, Number 1, April10 2021
 

Abstract
An exact solution based on refined third-order theory (TOT) has been presented for functionally graded porous curved beams having deep curvature. The displacement field of the refined TOT is derived by imposing the shear free conditions at the outer and inner surfaces of curved beams. The properties of the two phase composite are tailored according the power law rule and the effective properties are computed using Mori-Tanaka homogenization scheme. The equations of motion as well as consistent boundary conditions are derived using the Hamilton's principle. The curved beam stiffness coefficients (A, B, D) are obtained numerically using six-point Gauss integration scheme without compromising the accuracy due to deepness (1+z/R) terms. The porosity has been modeled assuming symmetric (even) as well as asymmetric (uneven) distributions across the cross section of curved beam. The programming has been performed in MATLAB and is validated with the results available in the literature as well as 2D finite element model developed in ABAQUS. The effect of inclusion of 1+z/R terms is studied for deflection, stresses and natural frequencies for FG curved beams of different radii of curvature. Results presented in this work will be useful for comparison of future studies.

Key Words
refined third-order theory; functionally graded material; deep curved beams; porosity; Mori-Tanaka; analytical solution

Address
Mirza S. Beg, Hasan M. Khalid and Mohd Y. Yasin: Smart Structures Lab, Department of Mechanical Engineering, Z. H. College of Engineering and Technology,
Aligarh Muslim University, Aligarh 202002, India
L. Hadji: Laboratory of Geomatics and Sustainable Development, Ibn Khaldoun University of Tiaret, Algeria



Abstract
This paper aims to improve the current state-of-the-art in long-term deflection prediction in steel-concrete composite beams. The efficiency of a time-dependent finite element model based on linear creep theory is verified with available experimental data. A parametric numerical study is then carried out, which focuses on the effects of concrete creep and/or shrinkage, ultimate shrinkage strain and reinforcing bars in the slab. The study shows that the long-term deformations in composite beams are dominated by concrete shrinkage and that a higher area of reinforcing bars leads to lower long-term deformations and steel stresses. The AISC model appears to overestimate the shrinkage-induced deflection. A modified ACI equation is proposed to quantify time-dependent deflections in composite beams. In particular, a modified reduction factor reflecting the influence of reinforcing bars and a coefficient reflecting the influence of ultimate shrinkage are introduced in the proposed equation. The long-term deflections predicted by this equation and the results of extensive numerical analyses are found to be in good agreement.

Key Words
composite beam; shrinkage; creep; time-dependent deflection; time-dependent design

Address
Tiejiong Lou, Sishun Wu and Bo Chen: Hubei Key Laboratory of Roadway Bridge & Structure Engineering, Wuhan University of Technology, 430070 Wuhan, China
Theodore L. Karavasilis: Department of Civil Engineering, University of Patras, GR-26500 Patras, Greece

Abstract
Eccentrically braced frames (EBFs) are utilized as a lateral resisting system in high seismic zones. Links are the primary source of energy dissipation and they are exposed to high deformation, which may lead to buckling. Web stiffeners were introduced to prevent buckling of shear link. AISC 341 provides the required vertical stiffeners for a shear link. In this study, different stiffener configurations were examined. The main objective is to improve the behavior of short links using different stiffener configurations. Pursuant to this goal, a comprehensive numerical study is conducted using ABAQUS. Shear links with different stiffener configurations were subjected to cyclic loading using loading protocol mandated by AISC 341. The results are compared in terms of energy dissipation and shear capacities and rupture index. The proposed stiffener configurations were further verified with different link length ratios, I-shapes and thickness of stiffener. Based on the results, the stiffener configuration with two vertical and two diagonal stiffeners perpendicular to each other is recommended. The proposed stiffener configuration can increase the shear capacity, energy dissipation capacity and the ratio of energy/weight up to 27%, 38% and 30%, respectively. Detailing of the proposed stiffener configuration is presented.

Key Words
link; stiffener; rupture index; EBF; energy dissipation; cyclic loading; numerical study; ABAQUS

Address
Yasin O. Özkilic: Department of Civil Engineering, Necmettin Erbakan University, 42100, Konya, Turkey

Abstract
This paper presents a high-order shear and normal deformation theory for the bending of FGM plates. The number of unknowns and governing equations of the present theory is reduced, and hence makes it simple to use. Unlike any other theory, the number of unknown functions involved in displacement field is only four, as against five or more in the case of other shear and normal deformation theories. Based on the novel shear and normal deformation theory, the position of neutral surface is determined and the governing equilibrium equations based on neutral surface are derived. There is no stretching–bending coupling effect in the neutral surface-based formulation, and consequently, the governing equations of functionally graded plates based on neutral surface have the simple forms as those of isotropic plates. Navier-type analytical solution is obtained for functionally graded plate subjected to transverse load for simply supported boundary conditions. The accuracy of the present theory is verified by comparing the obtained results with other quasi-3D higher-order theories reported in the literature. Other numerical examples are also presented to show the influences of the volume fraction distribution, geometrical parameters and power law index on the bending responses of the FGM plates are studied.

Key Words
bending analysis; functionally graded plate; new quasi-3D theory; neutral surface position

Address
Houari Hachemi and Abdelhakim Kaci: Universite Dr Tahar Moulay, Faculte de Technologie, Département de Genie Civil et Hydraulique,
BP 138Cité En-Nasr 20000 Saida, Algérie
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Fouad Bourada: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
Département des Sciences et de la Technologie, université de Tissemsilt, BP 38004 Ben Hamouda, Algérie
Abdeldjebbar 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
Kouider Halim Benrahou: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
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
Mesfer Mohammad Al-Zahrani: 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








Abstract
Irregularities of a building in plan and elevation, which results in the change in stiffness on different floors highly affect the seismic performance and resistance of a structure. This study motivated to investigate the seismic responses of high-rise steel-frame buildings of twelve stories with various stiffness irregularities. The building has five spans of 3200 mm distance in both X- and Z-directions in the plan. The design package SAP2000 was adopted for the design of beams and columns and resulted in the profile IPE500 for the beams of all floors and box sections for columns. The column cross-section dimensions vary concerning the number of the story; one to three: 0.50 X0.50X0.05m, four to seven: 0.45X0.45X0.05 m, and eight to twelve: 0.40X0.40X0.05 m. Real recorded ground accelerations obtained from the Vrancea earthquake in Romania together with dead and live loads corresponding to each story were considered for the applied load. The model was validated by comparing the results of the current method and literature considering a three-bay steel moment-resisting frame of eight-story height subject to seismic load. To investigate the seismic performance of the buildings, the time-history analysis was performed using ABAQUS. Deformed shapes corresponding to negative and positive peaks were provided followed by the story drifts and fragility curves which were used to examine the probability of collapse of the building. From the results, it was concluded that regular buildings provided a seismic performance much better than irregular buildings. Furthermore, it was observed that building with torsional irregularity was more vulnerable to seismic failure.

Key Words
seismic load; building irregularity; time history analysis; story drift; fragility curves; high-rise building; steel frame

Address
Behzad Mohammadzadeh: School of Civil, Environmental, and Architectural Engineering, Korea University, Seoul 02841, Republic of Korea;
Future-Shapers for Solving Global Problem in Construction (BK21 FOUR R&E Center for Civil,
Environmental and Architectural Engineering), Korea University, Seoul 02841, Republic of Korea
Junsuk Kang: Department of Landscape Architecture and Rural Systems Engineering, Seoul National University, Seoul 08826, Republic of Korea;
Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Republic of Korea;
Transdisciplinary Program in Smart City Global Convergence, Seoul National University, Seoul 08826, Republic of Korea



Abstract
Splitting tensile strength (STS) is an important mechanical parameter of concrete. This study offers novel methodologies for the early prediction of this parameter. Artificial neural network (ANN), which is a leading predictive method, is synthesized with two metaheuristic algorithms, namely atom search optimization (ASO) and equilibrium optimizer (EO) to achieve an optimal tuning of the weights and biases. The models are applied to data collected from the published literature. The sensitivity of the ASO and EO to the population size is first investigated, and then, proper configurations of the ASO-NN and EO-NN are compared to the conventional ANN. Evaluating the prediction results revealed the excellent efficiency of EO in optimizing the ANN. Accuracy improvements attained by this algorithm were 13.26 and 11.41% in terms of root mean square error and mean absolute error, respectively. Moreover, it raised the correlation from 0.89958 to 0.92722. This is while the results of the conventional ANN were slightly better than ASO-NN. The EO was also a faster optimizer than ASO. Based on these findings, the combination of the ANN and EO can be an efficient non-destructive tool for predicting the STS.

Key Words
structural engineering, concrete, tensile strength, neural network, metaheuristic algorithms

Address
Yinghao Zhao: Guangzhou Institute of Building Science Co., Ltd., Guangzhou 510440, China;
South China University of Technology, Guangzhou 510641, China
Xiaolin Zhong: Guangzhou Testing Centre of Construction quality & safety Co., Ltd., Guangzhou 510440, China
Loke Kok Foong: Institute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam;
Faculty of Civil Engineering, Duy Tan University, Da Nang 550000, Vietnam



Abstract
In this work, the dynamic response of functionally graded beams on variable elastic foundations is studied using a novel higher-order shear deformation theory (HSDT). Unlike the conventional HSDT, the present one has a new displacement field which introduces undetermined integral variables. The FG beams were assumed to be supported on Winkler-Pasternak type foundations in which the Winkler modulus is supposed to be variable in the length of the beam. The variable rigidity of the elastic foundation is assumed to be linear, parabolic and sinusoidal along the length of the beam. The material properties of the FG porous beam vary according to a power law distribution in terms of the volume fraction of the constituents. The equations of motion are determined using the virtual working principle. For the analytical solution, Navier method is used to solve the governing equations for simply supported porous FG beams. Numerical results of the present theory for the free vibration of FG beams resting on elastic foundations are presented and compared to existing solutions in the literature. A parametric study will be detailed to investigate the effects of several parameters such as gradient index, thickness ratio, porosity factor and foundation parameters on the frequency response of porous FG beams.

Key Words
functionally graded beams; higher shear deformations theories; variable elastic foundations; porosity

Address
Redhwane Ait Atmane: Laboratoire Génie Industriel et Développement Durable, Faculty of Technology, University of Relizane, Algeria
Noureddine Mahmoudi: Department of Mechanical Engineering, University of Saida, Algeria
Riadh Bennai: Department of civil engineering, Faculty of civil engineering and architecture, University of Hassiba Benbouali of Chlef, Algeria
Hassen Ait Atmane: Department of civil engineering, Faculty of civil engineering and architecture, University of Hassiba Benbouali of Chlef, Algeria;
Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria;
YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea




Abstract
This research endeavor intends to use the implicit finite element method to investigate the structural response of steel shear walls with partial plate-column connection. To this end, comprehensive verification studies are initially performed by comparing the numerical predictions with several reported experimental results in order to demonstrate the reliability and accuracy of the implicit analysis method. Comparison is made between the hysteresis curves, failure modes, and base shear capacities predicted numerically using ABAQUS software and obtained/observed experimentally. Following the validation of the finite element analysis approach, the effects of partial plate-column connection on the strength and stiffness performances of steel shear wall systems with different web-plate slenderness and aspect ratios under monotonic loading are investigated through a parametric study. While removal of the connection between the web-plate and columns can be beneficial by decreasing the overall system demand on the vertical boundary members, based on the results and findings of this study such detachment can lower the stiffness and strength capacities of steel shear walls by about 25%, on average.

Key Words
finite element simulation; implicit analysis method; steel plate shear walls; partial plate-column connection; structural response assessment

Address
Mojtaba Gorji Azandariani, Majid Gholhaki and Mohammad Ali Kafi: Structural Engineering Division, Faculty of Civil Engineering, Semnan University, Semnan, Iran
Tadeh Zirakian: Department of Civil Engineering and Construction Management, California State University, Northridge, CA, USA
Afrasyab Khan: Department of Hydraulics and Hydraulic and Pneumatic Systems, South Ural State University, Chelyabinsk, Russian Federation
Hamid Abdolmaleki: Department of Civil Engineering, Tuyserkan Branch, Islamic Azad University, Tuyserkan, Iran
Hamid Shojaeifar: Department of Civil Engineering, Faculty of Maragheh, Maragheh Branch, Technical and Vocational University (TUV), Tehran, Iran



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