Abstract
This paper addresses the finite element modeling of functionally graded porous (FGP) beams for free vibration and
buckling behaviour cases. The formulated finite element is based on simple and efficient higher order shear deformation theory.
The key feature of this formulation is that it deals with Euler-Bernoulli beam theory with only three unknowns without requiring
any shear correction factor. In fact, the presented two-noded beam element has three degrees of freedom per node, and the
discrete model guarantees the interelement continuity by using both C0 and C1 continuities for the displacement field and its first
derivative shape functions, respectively. The weak form of the governing equations is obtained from the Hamilton principle of
FGP beams to generate the elementary stiffness, geometric, and mass matrices. By deploying the isoparametric coordinate
system, the derived elementary matrices are computed using the Gauss quadrature rule. To overcome the shear-locking
phenomenon, the reduced integration technique is used for the shear strain energy. Furthermore, the effect of porosity
distribution patterns on the free vibration and buckling behaviours of porous functionally graded beams in various parameters is
investigated. The obtained results extend and improve those predicted previously by alternative existing theories, in which
significant parameters such as material distribution, geometrical configuration, boundary conditions, and porosity distributions
are considered and discussed in detailed numerical comparisons. Determining the impacts of these parameters on natural
frequencies and critical buckling loads play an essential role in the manufacturing process of such materials and their related
mechanical modeling in aerospace, nuclear, civil, and other structures.
Key Words
buckling; finite element method; free vibration; functionally graded porous (FGP) beams; shear deformation
beam theory; two-noded isoparametric finite element
Address
Abdelhak Mesbah: Smart Structures Laboratory, Faculty of Science & Technology, Civil Engineering Department, University of Ain Témouchent, Po Box 284, 46000 Ain-Temouchent, Algeria
Zakaria Belabed: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Technology, Institute of Science and Technology, Naama University Center, BP 66, 45000 Naama, Algeria
Khaled Amara: Engineering and Sustainable Development Laboratory, University of Ain Temouchent, Ain Temouchent 46000, Algeria
Abdelouahed Tounsi: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabi; YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea
Abdelmoumen A. Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, University of Sidi Bel Abbés, Algeria
Fouad Bourada: Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, Algeria; Département des Sciences et de la Technologie, Université de Tissemsilt, BP 38004 Ben Hamouda, Algérie
Abstract
Herein, we present effective polygonal finite elements to which the strain-smoothed element (SSE) method is applied. Recently, the SSE method has been developed for conventional triangular and quadrilateral finite elements; furthermore, it has been shown to improve the performance of finite elements. Polygonal elements enable various applications through flexible mesh handling; however, further development is still required to use them more effectively in engineering practice. In this study, piecewise linear shape functions are adopted, the SSE method is applied through the triangulation of polygonal elements, and a smoothed strain field is constructed within the element. The strain-smoothed polygonal elements pass basic tests and show improved convergence behaviors in various numerical problems.
Key Words
finite element analysis; polygonal elements; solid elements; strain-smoothed element method
Address
Hoontae Jung, Phill-Seung Lee: Department of Mechanical Engineering, Korean Advanced Institute for Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Chaemin Lee: Department of Mechanical Engineering, Korean Advanced Institute for Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea; Department of Safety Engineering, Chungbuk National University, Chungbuk 28644, Republic of Korea
Abstract
A significant component of many civil constructions such as buildings, reservoirs, bridges, and sports halls, concrete has become increasingly popular due to its versatile properties. Concrete's internal characteristics change due to the use of different types of fibers, including changes in its microstructure, volume, and hole dimensions. Additionally, the type, dimensions, and distribution of fibers in concrete can affect the results of flexural strength tests by affecting its compressive and
tensile strength. Due to a lack of information, fiber concrete is a new composite material in the production industry that requires laboratory studies to determine its behavior. This study investigated the bending behavior of multilayer slabs made of concrete reinforced by polyamide-propylene fibers against impact in weight lifting exercises. Results showed that adding fibers to concrete slab samples improved the mechanical properties while replacing them hurt the mechanical properties and failure of polymer fiber-reinforced concrete. On the other hand, adding and replacing fibers increases durability and has a positive effect.
Key Words
concrete; fiber; polymer; slabs; weightlifting
Address
Zhi Li: Physical Education Department, Tianjin University of Commerce, Beichen 300134, Tianjin, China
Abstract
The optimization of reinforced concrete (RC) cantilever retaining walls is a complex problem and requires the use of
advanced techniques like metaheuristic algorithms. For this purpose, an optimization model must first be developed, which involves mathematical complications, multidisciplinary knowledge, and programming skills. This task has proven to be too arduous and has halted the mainstream acceptance of optimization. Therefore, it is necessary to unravel the complications of optimization into an easily applicable form. Currently, the most commonly used method for designing retaining walls is by following the proportioning limits provided by the ACI handbook. However, these limits, derived manually, are not verified by any optimization technique. There is a need to validate or modify these limits, using optimization algorithms to consider them as optimal limits. Therefore, this study aims to propose updated proportioning limits for the economical design of a RC cantilever
retaining wall through a comprehensive parametric investigation using the genetic algorithm (GA). Multiple simulations are run to examine various design parameters, and trends are drawn to determine effective ranges. The optimal limits are derived for 5 geometric and 3 reinforcement variables and validated by comparison with their predecessor, ACI's preliminary proportioning
limits. The results indicate close proximity between the optimized and code-provided ranges; however, the use of optimal limits can lead to additional cost optimization. Modifications to achieve further optimization are also discussed. Besides the geometric variables, other design parameters not covered by the ACI building code, like reinforcement ratios, bar diameters, and material strengths, and their effects on cost optimization, are also discussed. The findings of this investigation can be used by experienced engineers to refine their designs, without delving into the complexities of optimization.
Address
Mansoor Shakeel, Rizwan Azam and Muhammad R. Riaz: Department of Civil Engineering, University of Engineering and Technology, Lahore, 54890, Pakistan
Abstract
This paper presents a technique for determining the optimal number of elements in stochastic finite element analysis
based on reliability analysis. Using the change-of-variable perturbation stochastic finite element approach, the probability density function of the dynamic responses of stochastic structures is explicitly determined. This method combines the perturbation stochastic finite element method with the change-of-variable technique into a united model. To further examine the relationships between the random fields, discretization of the random field parameters, such as the variance function and the scale of fluctuation, is also performed. Accordingly, the reliability index is calculated based on the explicit probability density
function of responses with Gaussian or non-Gaussian random fields in any number of elements corresponding to the random
field discretization. The numerical examples illustrate the effectiveness of the proposed method for a one-dimensional cantilever reinforced concrete column and a two-dimensional steel plate shear wall. The benefit of this method is that the probability density function of responses can be obtained explicitly without the use simulation techniques. Any type of random variable with any statistical distribution can be incorporated into the calculations, regardless of the restrictions imposed by the type of
statistical distribution of random variables. Consequently, this method can be utilized as a suitable guideline for the efficient implementation of stochastic finite element analysis of structures, regardless of the statistical distribution of random variables.
Key Words
change-of-variable; perturbation; probability density function; reliability analysis; stochastic finite element
Address
Rezan Chobdarian, Azad Yazdani, Hooshang Dabbagh and Mohammad-Rashid Salimi: Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran
Abstract
Boundary condition is an important factor affecting the vibration characteristics of structures, under different
boundary conditions, structures will exhibit different vibration behaviors. On the basis of the previous work, this paper extends to the nonlinear resonance behavior of axially moving graphene platelets reinforced metal foams (GPLRMF) plates with geometric imperfection under different boundary conditions. Based on nonlinear Kirchhoff plate theory, the motion equations are derived. Considering three boundary conditions, including four edges simply supported (SSSS), four edges clamped (CCCC), clamped-clamped-simply-simply (CCSS), the nonlinear ordinary differential equation system is obtained by Galerkin method, and then the equation system is solved to obtain the nonlinear ordinary differential control equation which only including transverse displacement. Subsequently, the resonance response of GPLRMF plates is obtained by perturbation method. Finally, the effects of different boundary conditions, material properties (including the GPLs patterns, foams distribution, porosity coefficient and GPLs weight fraction), geometric imperfection, and axial velocity on the resonance of GPLRMF plates are investigated.
Abstract
The main objective of this research work is to present analytical solutions for the thermoelastic bending analysis of sandwich plates made of functionally graded materials with an arbitrary gradient. The governing equations of equilibrium are solved for a functionally graded sandwich plates under the effect of thermal loads. The transverse shear and normal strain and stress effects on thermoelastic bending of such sandwich plates are considered. Field equations for functionally graded sandwich plates whose deformations are governed by either the shear deformation theories or the classical theory are derived.
Displacement functions that identically satisfy boundary conditions are used to reduce the governing equations to a set of coupled ordinary differential equations with variable coefficients. The results of the shear deformation theories are compared together. Numerical results for deflections and stresses of functionally graded metal–ceramic plates are investigated.
Address
Mohammed Sid Ahmed Houari, Aicha Bessaim: Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie, Université Mustapha Stambouli, Mascara, Algérie
Smain Bezzina: Mechanical Engineering Department, King Abdulaziz University, P.O. Box: 80204, Jeddah 21589, Saudi Arabia
Abdelouahed Tounsi: YFL (Yonsei Frontier Lab), Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Republic of Korea; Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Kingdom of Saudi Arabia; Material and Hydrology Laboratory, Faculty of Technology, Civil Engineering Department, University of Sidi Bel Abbes, BP 89 Sidi Bel Abbes, 22000, Algeria
Abstract
This study presents an experiment and analysis to compare the seismic behavior of full-scale reinforced concrete beam-column joint strengthened by prestressed steel strips, externally bonded steel plate, and CFRP sheets. For experimental investigation, five specimens, including one joint without any retrofitting, one joint retrofitted by externally bonded steel plate, one joint retrofitted by CFRP sheets, and two joints retrofitted by prestressed steel strips, were tested under cyclic-reserve loading. The failure mode, strain response, shear deformation, hysteresis behavior, energy dissipation capacity, stiffness degradation and damage indexes of all specimens were analyzed according to experimental study. It was found that prestressed
steel strips, steel plate and CFRP sheets improved shear resistance, energy dissipation capacity, stiffness degradation behavior and reduced the shear deformation of the joint core area, as well as changed the failure pattern of the specimen, which led to the failure mode changed from the combination of flexural failure of beams and shear failure of joints core to the flexural failure of beams. In addition, the beam-column joint retrofitted by steel plate exhibited a high bearing capacity, energy consumption capacity and low damage index compared with the joint strengthened by prestressed steel strip, and the prestressed steel strips reinforced joint showed a high strength, energy dissipation capacity and low shear deformation, stirrups strains and damage index compared to the CFRP reinforced joint, which indicated that the frame joints strengthened with steel plate exhibited the most excellent seismic behavior, followed by the prestressed steel strips.
Key Words
experimental study; frame joints; retrofitting methods; seismic performance
Address
Yang Chen: Department of Civil Engineering, Shanghai University, Shanghai, 200444, China; State Key Laboratory of Green Building in Western China, Xi
Abstract
This paper presents the experimental and numerical evaluations on the circular SFRC columns reinforced GFRP rebars under the axial compressive loading. The test programs were designed to inquire and compare the effects of different parameters on the columns' structural behavior by performing experiments and finite element modeling. The research variables were conventional concrete (CC), fiber concrete (FC), types of longitudinal steel/GFRP rebars, and different configurations of lateral rebars. A total of 16 specimens were manufactured and categorized into four groups based on different rebar-concrete arrangements including GRCC, GRFC, SRCC, and SRFC. Adding steel fibers (SFs) into the concrete, it was essential to modify the concrete damage plastic (CDP) model for FC columns presented in the finite element method (FEM) using ABAQUS 6.14 software. Failure modes of the columns were similar and results of peak loads and corresponding deflections of compression columns showed a suitable agreement in tests and numerical analysis. The behavior of GFRP-RC and steel-RC columns was relatively linear in the pre-peak branch, up to 80-85% of their ultimate axial compressive loads. The axial compressive loads of GRCC and GRFC columns were averagely 80.5% and 83.6% of axial compressive loads of SRCC and SRFC columns. Also, DIs of GRCC and GRFC columns were 7.4% and 12.9% higher than those of SRCC and SRFC columns. Partially, using SFs compensated up to 3.1%, the reduction of the compressive strength of the GFRP-RC columns as compared with the steel-RC columns. The effective parameters on increasing the DIs of columns were higher volumetric ratios (up to 12%), using SFs into concrete (up to 6.6%), and spiral (up to 5.5%). The results depicted that GFRP-RC columns had higher DIs and lower peak loads compared with steel-RC columns.
Key Words
axial compressive load; Conventional Concrete (CC); Ductility Index (DI); Fiber Concrete (FC); GFRP rebars; numerical analysis
Address
Iman Saffarian, Gholam Reza Atefatdoost: Department of Civil Engineering, Estahban Branch, Islamic Azad University, Estahban, Iran
Seyed Abbas Hosseini: Faculty of Technology and Mining, Yasouj University, Choram, Iran
Leila Shahryari: Department of Civil Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran
Abstract
As the key part in the reinforced concrete column-steel beam (RCS) frame, the beam-column joints are usually subjected the axial force, shear force and bending moment under seismic actions. With the aim to study the seismic behavior of RCS joints with and without RC slab, the quasi-static cyclic tests results, including hysteretic curves, slab crack development, failure mode, strain distributions, etc. were discussed in detail. It is shown that the composite action between steel beam and RC slab can significantly enhance the initial stiffness and loading capacity, but lead to a changing of the failure mode from beam flexural failure to the joint shear failure. Based on the analysis of shear failure mechanism, the calculation formula accounting for the influence of RC slab was proposed to estimate shear strength of RCS joint. In addition, the finite element model (FEM) was developed by ABAQUS and a series of parametric analysis model with RC slab was conducted to investigate the influence of the face plates thickness, slab reinforcement diameter, beam web strength and inner concrete strength on the shear strength of joints. Finally, the proposed formula in this paper is verified by the experiment and FEM parametric analysis results.
Key Words
failure mode; finite element analysis; RC slab; reinforced concrete column-steel beam (RCS) joint; seismic performance; shear strength
Address
Tong Li, Huan Li, Liquan Xiong: College of Civil Engineering, Xi'an University of Architecture & Technology, Xi'an 710055, China
Jinjie Men: College of Civil Engineering, Xi'an University of Architecture & Technology, Xi'an 710055, China; Key Laboratory of Structural Engineering and Earthquake Resistance, Ministry of Education, Xi'an University of Architecture & Technology, Xi'an 710055, China
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