Abstract
In this research, a new two-dimensional (2D) and quasi three-dimensional (quasi-3D) higher order shear
deformation theory is devised to address the bending problem of functionally graded plates resting on an elastic foundation. The
displacement field of the suggested theories takes into account a parabolic transverse shear deformation shape function and
satisfies shear stress free boundary conditions on the plate surfaces. It is expressed as a combination of trigonometric and
exponential shear shape functions. The Pasternak mathematical model is considered for the elastic foundation. The material
properties vary constantly across the FG plate thickness using different distributions as power-law, exponential and Mori–
Tanaka model. By using the virtual works principle and Navier's technique, the governing equations of FG plates exposed to
sinusoidal and evenly distributed loads are developed. The effects of material composition, geometrical parameters, stretching
effect and foundation parameters on deflection, axial displacements and stresses are discussed in detail in this work. The
obtained results are compared with those reported in earlier works to show the precision and simplicity of the current
formulations. A very good agreement is found between the predicted results and the available solutions of other higher order
theories. Future mechanical analyses of three-dimensionally FG plate structures can use the study's findings as benchmarks.
Address
Fatima Z. Zaoui and Djamel Ouinas:Laboratory of Science and Technology Environment and Valorization, Faculty of Sciences and Technology/Ibn Badis University,
27000 Mostaganem, Algeria
Abdelouahed Tounsi:1)Material and Hydrology Laboratory, Civil Engineering Department, Faculty of Technology / Djilali Liabes University,
22000 Sidi Bel Abbes, Algeria
2)Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
3)YFL (Yonsei Frontier Lab), Yonsei University, Seoul 03722, Korea
Belkacem Achour and Tayyab A. Butt:Civil Engineering Department, University of Ha'il, KSA, Saudi Arabia
Jaime A. Vina Olay:Department of Materials Science and Metallurgical Engineering, University of Oviedo, Viesques Campus,33203 Gijon, Asturias, Spain
Abstract
This paper proposes an efficient approach for the structural topology optimization of bi-directional functionally
graded structures by incorporating popular radial basis functions (RBFs) into an implicit level set (ILS) method. Compared to
traditional element density-based methods, a level set (LS) description of material boundaries produces a smoother boundary
description of the design. The paper develops RBF implicit modeling with multiquadric (MQ) splines, thin-plate spline (TPS),
exponential spline (ES), and Gaussians (GS) to define the ILS function with high accuracy and smoothness. The optimization
problem is formulated by considering RBF-based nodal densities as design variables and minimizing the compliance objective
function. A LS-RBF optimization method is proposed to transform a Hamilton-Jacobi partial differential equation (PDE) into a
system of coupled non-linear ordinary differential equations (ODEs) over the entire design domain using a collocation
formulation of the method of lines design variables. The paper presents detailed mathematical expressions for BiDFG beams
topology optimization with two different material models: continuum functionally graded (CFG) and mechanical functionally
graded (MFG). Several numerical examples are presented to verify the method's efficiency, reliability, and success in accuracy,
convergence speed, and insensitivity to initial designs in the topology optimization of two-dimensional (2D) structures. Overall,
the paper presents a novel and efficient approach to topology optimization that can handle bi-directional functionally graded
structures with complex geometries.
Address
Wonsik Jung, Thanh T. Banh, Nam G. Luuc and Dongkyu Lee:Department of Architectural Engineering, Sejong University, Seoul 05006, Republic of Korea
Abstract
The establishment of a hysteretic model which can accurately predict the hysteretic characteristics of the stud
connection is of utmost importance for the seismic assessment of composite structures. In this paper, the Bouc-Wen-Baber-Noori
(BWBN) model was adopted to describe the typical hysteretic characteristics of stud connections. Meanwhile, the NewtonRaphson iterative procedure and the Backward Euler method were used to determine the restoring force, and the Genetic
Algorithm was employed to identify the parameters of the BWBN model based on the experimental data consisting of eight
specimens. The accuracy of the identified parameters was demonstrated by comparison with the experimental data. Finally,
prediction equations for the BWBN model parameters were developed in terms of the physical parameters of stud connections,
which provides an approach to get the hysteretic response of stud connections conveniently.
Address
Xi Qin:1)School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
2)Zhejiang Institute of Communications, Hangzhou 311100, China
Guotao Yang:School of Civil Engineering, Qingdao University of Technology, Qingdao 266033, China
Abstract
Numerous methods have been proposed in predicting formability of sheet metals based on microstructural and
macro-scale properties of sheets. However, there are limited number of papers on the optimization problem to increase
formability of sheet metals. In the present study, we aim to use novel optimization algorithms in neural networks to maximize
the formability of sheet metals based on tensile curve and texture of aluminum sheet metals. In this regard, experimental and
numerical evaluations of effects of texture and tensile properties are conducted. The texture effects evaluation is performed using
Taylor homogenization method. The data obtained from these evaluations are gathered and utilized to train and validate an
artificial neural network (ANN) with different optimization methods. Several optimization method including grey wolf
algorithm (GWA), chimp optimization algorithm (ChOA) and whale optimization algorithm (WOA) are engaged in the
optimization problems. The results demonstrated that in aluminum alloys the most preferable texture is cube texture for the most
formable sheets. On the other hand, slight differences in the tensile behavior of the aluminum sheets in other similar conditions
impose no significant decreases in the forming limit diagram under stretch loading conditions.
Address
Fuyuan Dong and Junfeng Hou:1)School of Materials Science and Engineering, North Minzu University, Yinchuan 750021, Ningxia, China
2)Key Laboratory of Powders & Advanced Ceramics, North Minzu University, Yinchuan 750021, Ningxia, China
Wang Xu and Zhengnan Wu:School of Materials Science and Engineering, North Minzu University, Yinchuan 750021, Ningxia, China
Abstract
Steel corrosion induces structural deterioration of concrete-filled steel tubes (CFSTs), and any potential extreme
action on a corroded CFST would pose a severe threat. This paper presents a comprehensive investigation on the lateral impact
behaviour of CFSTs suffering from localised pitting corrosion damage. A refined finite element analysis model is developed for
the simulation of locally corroded CFSTs subjected to lateral impact loads, which takes into account the strain rate effects on
concrete and steel materials as well as the random nature of corrosion pits, i.e., the distribution patterns and the geometric
characteristics. Full-range nonlinear analysis on the lateral impact behaviour in terms of loading and deforming time-history
relations, nonlinear material stresses, composite actions, and energy dissipations are presented for CFSTs with no corrosion,
uniform corrosion and pitting corrosion, respectively. Localised pitting corrosion is found to pose a more severe deterioration on
the lateral impact behaviour of CFSTs due to the plastic deformation concentration, the weakened confinement and the reduction
in energy absorption capacity of the steel tube. An extended parametric study is then carried out to identify the influence of the
key parameters on the lateral impact behaviour of CFSTs with localised pitting corrosion. Finally, simplified design methods
considering the features of pitting corrosion are proposed to predict the dynamic flexural capacity of locally pitted CFSTs
subjected to lateral impact loads, and reasonable accuracy is obtained.
Address
Gen Li:1)Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
2)School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
Chao Hou:Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China
Luming Shen:School of Civil Engineering, The University of Sydney, Sydney, NSW 2006, Australia
Chuan-Chuan Hou:School of Transportation Science and Engineering, Beihang University, Beijing, 100191, P. R. China
Abstract
Taking a look at the previously published papers, it is revealed that there is a porosity index limitation (around 0.35)
for the mechanical behavior analysis of the functionally graded porous (FGP) structures. Over mentioned magnitude of the
porosity index, the elastic modulus falls below zero for some parts of the structure thickness. Therefore, the current paper is
presented to analyze the vibrational behavior of the FGP Timoshenko beams (FGPTBs) using a novel refined formulation
regardless of the porosity index magnitude. The silica aerogel foundation and various hydrothermal loadings are assumed as the
source of external forces. To obtain the FGPTB's properties, the power law is hired, and employing Hamilton's principle in
conjunction with Navier's solution method, the governing equations are extracted and solved. In the end, the impact of the
various variables as different beam materials, elastic foundation parameters, and porosity index is captured and displayed. It is
revealed that changing hygrothermal loading from non-linear toward uniform configuration results in non-dimensional
frequency and stiffness pushing up. Also, Al – Al2O3 as the material composition of the beam and the porosity presence with the
O pattern, provide more rigidity in comparison with using other materials and other types of porosity dispersion. The presented
computational model in this paper hopes to help add more accuracy to the structures' analysis in high-tech industries.
Key Words
functionally graded porous structure; refined formulation; silica aerogel foundation; Timoshenko beam;
various hygrothermal loading; vibration
Address
Mohammad Khorasani:1)Department of Mechanical & Industrial Engineering, Louisiana State University, 3304 S Quad Dr, LA 70803, Baton Rouge, U.S.A.
2)Department of Basic and Applied Sciences for Engineering, Sapienza University, Via Scarpa 16, 00161, Rome, Italy
Luca Lampani:Department of Mechanical and Aerospace Engineering, Sapienza University, Via Eudossiana 18, 00184, Rome, Italy
Abdelouahed Tounsi:1)Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals,
31261 Dhahran, Eastern Province, Saudi Arabia
2)Yonsei Frontier Laboratory, Yonsei University, Seoul, Korea
Abstract
Concrete-filled steel tubular columns with double inner steel tubes (CFST-DIST) are a novel type of composite
members developed from conventional concrete-filled steel tubular (CFST) columns. This paper investigates the structural
performance of circular CFST-DIST stub columns using nonlinear finite element (FE) analysis. A numerical model was
developed and verified against existing experimental test results. The validated model was then used to compare circular CFSTDIST stub columns' behavior with their concrete-filled double skin steel tubular (CFDST) and CFST counterparts. A parametric
study was performed to ascertain the effects of geometric and material properties on the axial performance of CFST-DISTs. The
FE results and the available test data were used to assess the accuracy of the European and American design regulations in
predicting the axial compressive capacity of circular CFST-DIST stub columns. Finally, a new design model was recommended
for estimating the compressive capacity of CFST-DISTs. Results clarified that circular CFST-DIST columns had the advantages
of their CFST counterparts but with better ductility and strength-to-weight ratio. Besides, the investigated design codes led to
conservative predictions of the compressive capacity of circular CFST-DIST columns.
Abstract
The self-centering energy-dissipating coupled wall panels (SECWs) possess a dual capacity of resiliency and energy
dissipation. Used in steel frames, the SECWs can localize the damage of structures and reduce residual drifts. Based on
OpenSEES, the nonlinear models were established and validated by experimental results. The seismic design procedure of steel
frame with SECW structures (SF-SECW) was proposed in accordance with four-level seismic fortification objectives. Nonlinear
time-history response analyses were carried out to validate the reasonability of seismic design procedure for 6-story and 12-story
structures. Results show that the inter-story drifts of designed structures are less than drift limits. According to incremental
dynamic analyses (IDA), the fragility curves of mentioned-above structure models under different limit states were obtained.
The results indicate that designed structures have good seismic performance and meet the seismic fortification objectives.
Key Words
seismic collapse; seismic performance; self-centering; steel moment frames; wall panels
Address
Lu Sui, Hanheng Wu, Menglong Tao, Zhichao Jia and Tianhua Zhou:School of Civil Engineering, Chang'an University, Xi'an 710061, China
