Abstract
Based on the consistent couple stress theory (CCST), we develop a unified formulation for analyzing the static
bending and free vibration behaviors of functionally graded (FG) microscale beams (MBs). The strong forms of the CCSTbased Euler-Bernoulli, Timoshenko, and Reddy beam theories, as well as the CCST-based sinusoidal, exponential, and
hyperbolic shear deformation beam theories, can be obtained by assigning some specific shape functions of the shear
deformations varying through the thickness direction of the FGMBs in the unified formulation. The above theories are thus
included as special cases of the unified CCST. A comparative study between the results obtained using a variety of CCST-based
beam theories and those obtained using their modified couple stress theory-based counterparts is carried out. The impacts of
some essential factors on the deformation, stress, and natural frequency parameters of the FGMBs are examined, including the
material length-scale parameter, the aspect ratio, and the material-property gradient index.
Abstract
There are many challenges in the construction of large-section tunnels, such as extremely soft rock and fractured
zones. In order to solve these problems, the confined concrete support technology is proposed to control the surrounding rocks.
The large-scale laboratory test is carried out to clarify mechanical behaviours of the combined confined concrete and traditional
I-steel arches. The test results show that the bearing capacity of combined confined concrete arch is 3217.5 kN, which is 3.12
times that of the combined I-steel arch. The optimum design method is proposed to select reasonable design parameters for
confined concrete arch. The parametric finite element (FE) analysis is carried out to study the effect of the design factors via
optimum design method. The steel pipe wall thickness and the longitudinal connection ring spacing have a significant effect on
the bearing capacity of the combined confined concrete arch. Based on the above research, the confined concrete support
technology is applied on site. The field monitoring results shows that the arch has an excellent control effect on the surrounding
rock deformation. The results of this research provide a reference for the support design of surrounding rocks in large-section
tunnels.
Key Words
combined confined concrete arch; design optimization; large-section tunnels; on-field experimental tests;
parametric finite element analysis
Address
Jiang Bei,Xu Shuo, Wei Hua Yong and Ma Feng Li:State Key Laboratory for Tunnel Engineering, China University of Mining & Technology-Beijing, Beijing 100083, China
Wang Qi:1)State Key Laboratory for Tunnel Engineering, China University of Mining & Technology-Beijing, Beijing 100083, China
2)Geotechnical and Structural Engineering Research Center, Shandong University, Jinan 250061, China
Xin Zhong Xin:Geotechnical and Structural Engineering Research Center, Shandong University, Jinan 250061, China
Abstract
In this paper, structural behavior under fire conditions is comprehensively examined, and a novel software interface
for testing interfaces efficiently is developed and validated. In order to accurately assess the response of structures to fire
scenarios, advanced simulation techniques and modeling approaches are incorporated into the study. This interface enables
accurate heat transfer analysis and thermo-mechanical simulations by integrating software tools such as CSI ETABS, CSI
SAP2000, and OpenSees. Heat transfer models can be automatically generated, simulation outputs processed, and structural
responses interpreted under a variety of fire scenarios using the proposed technique. As a result of rigorous testing and validation
against established methods, including Cardington tests on scales and hybrid simulation approaches, the software interface has
been proven to be effective and accurate. The analysis process is streamlined by this interface, providing engineers and
researchers with a robust tool for assessing structural performance under fire conditions.
Key Words
computer-aided design; finite element method; opensees fire; thermal analysis
Address
Seong-Hoon Jeong:Department of Architectural Engineering, Inha University, Incheon, South Korea
Ehsan Mansouri:2)Institute of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
3)Faculty of Natural Sciences, Duy Tan University, Da Nang 550000, Vietnam
Nadia Ralston:Department of Civil and Environmental Engineering, Princeton University, United State
Jong-Wan Hu:1)Department of Civil and Environmental Engineering, Incheon National University, South Korea
2)Incheon Disaster Prevention Research Center, Incheon National University, South Korea
Abstract
In this research, a semi-analytical solution is presented for computing mechanical displacements and thermal
stresses in rotating thick cylindrical pressure vessels made of functionally graded material (FGM). The modulus of elasticity,
linear thermal expansion coefficient, and density of the cylinder are assumed to change along the axial direction as a power-law
function. It is also assumed that Poisson's ratio and thermal conductivity are constant. This cylinder was subjected to nonuniform internal pressure and thermal loading. Thermal loading varies in two directions. The governing equations are derived by
the first-order shear deformation theory (FSDT). Using the multilayer method, a functionally graded (FG) cylinder with variable
thickness is divided into n homogenous disks, and n sets of differential equations are obtained. Applying the boundary
conditions and continuity conditions between the layers, the solution of this set of equations is obtained. To the best of the
researchers' knowledge, in the literature, there is no study carried out bi-directional thermoelastic analysis of clamped-clamped
rotating FGM thick-walled cylindrical pressure vessels under variable pressure in the longitudinal direction.
Key Words
First-Order shear Deformation Theory (FSDT); Functionally Graded Material (FGM); rotating cylinder;
thermoelastic; two-direction
Address
Fatemeh Ramezani and Mohammad Zamani Nejad:Department of Mechanical Engineering, Yasouj University, Yasouj, Iran
Abstract
Due to the fast development of constructions in recent years, there has been a rapid consumption of fresh water and
river sand. In the production of concrete, alternatives such as sea water and sea sand are available. The near surface mounted
(NSM) technique is one of the most important methods of strengthening. Aluminum alloy (AA) bars are non-rusting and
suitable for usage with sea water and sand concrete (SSC). The goal of this study was to enhance the shear behaviour of SSCbeams strengthened with NSM AA bars. Twenty-four RC beams were cast from fresh water river sand concrete (FRC) and SSC
before being tested in four-point flexure. All beams are the same size and have the same internal reinforcement. The major
factors are the concrete type (FRC or SSC), the concrete degree (C25 or C50 with compressive strength = 25 and 50 MPa,
respectively), the presence of AA bars for strengthening, the direction of AA bar reinforcement (vertical or diagonal), and the AA
bar ratio (0, 0.5, 1, 1.25 and 2 %). The beams' failure mechanism, load-displacement response, ultimate capacity, and ductility
were investigated. Maximum load and ductility of C25-FRC-specimens with vertical and diagonal AA bar ratios (1%) were
100,174 % and 140, 205.5 % greater, respectively, than a matching control specimen. The ultimate load and ductility of all SSCbeams were 16-28 % and 11.3-87 % greater, respectively, for different AA bar methods than that of FRC-beams. The ultimate
load and ductility of C25-SSC-beams vertically strengthened with AA bar ratios were 66.7-172.7 % and 89.6-267.9 % higher
than the unstrengthened beam, respectively. When compared to unstrengthened beams, the ultimate load and ductility of C50-
SSC-beams vertically reinforced with AA bar ratios rose by 50-120 % and 45.4-336.1 %, respectively. National code proposed
formulae were utilized to determine the theoretical load of tested beams and compared to matching experimental results. The
predicted theoretical loads were found to be close to the experimental values.
Abstract
This study investigates a new seismic retrofit system that utilizes rotational friction dampers and axial springs. The
retrofit system involves a steel frame with rotational friction dampers (RFD) at beam-column joints and linear springs at the
corners, providing energy dissipation and self-centering capabilities to existing structures. The axial spring acts as a selfcentering mechanism that eliminates residual deformations, while the friction damper mitigates seismic damage. To evaluate the
seismic performance of the proposed retrofit system, a series of cyclic loading tests were carried out on a steel beam-column
subassembly equipped with the proposed devices. An analytical model was then developed to validate the experimental results.
A performance point ratio (PPR) was presented to optimize the design parameters of the retrofit system, and a performancebased seismic design strategy was developed based on the PPR. The retrofit system's effectiveness and the presented
performance-based design approach were evaluated through case study models, and the analysis results demonstrated that the
developed retrofit system and the performance-based design procedure were effective in retrofitting structures for multi-level
design objectives.
Key Words
performance-based seismic design; seismic retrofit; self-centering; steel frame
Address
Masoum M. Gharagoz:1)Department of Civil Engineering, School of Engineering, Aalto University, Finland
2)Department of Global Smart City, Sungkyunkwan University, South Korea
Seungho Chun:Department of Global Smart City, Sungkyunkwan University, South Korea
Mohamed Noureldin:Department of Civil Engineering, School of Engineering, Aalto University, Finland
Jinkoo Kim:Department of Global Smart City, Sungkyunkwan University, South Korea
Abstract
In this research paper, and for the first time, wave propagations in sigmoidal imperfect functionally graded material
plates are investigated using a simplified quasi-three-dimensionally higher shear deformation theory (Quasi-3D HSDTs). By
employing an indeterminate integral for the transverse displacement in the shear components, the number of unknowns and
governing equations in the current theory is reduced, thereby simplifying its application. Consequently, the present theories
exhibit five fewer unknown variables compared to other Quasi-3D theories documented in the literature, eliminating the need for
any correction coefficients as seen in the first shear deformation theory. The material properties of the functionally graded plates
smoothly vary across the cross-section according to a sigmoid power law. The plates are considered imperfect, indicating a pore
distribution throughout their thickness. The distribution of porosities is categorized into two types: even or uneven, with linear
(L)-Type, exponential (E)-Type, logarithmic (Log)-Type, and Sinus (S)-Type distributions. The current quasi-3D shear
deformation theories are applied to formulate governing equations for determining wave frequencies, and phase velocities are
derived using Hamilton's principle. Dispersion relations are assumed as an analytical solution, and they are applied to obtain
wave frequencies and phase velocities. A comprehensive parametric study is conducted to elucidate the influences of
wavenumber, volume fraction, thickness ratio, and types of porosity distributions on wave propagation and phase velocities of
the S-FGM plate. The findings of this investigation hold potential utility for studying and designing techniques for ultrasonic
inspection and structural health monitoring.
Key Words
even and uneven porosity; guided wave; phase velocity; Qausi-3D HSDTs; S-FGM
Address
Mokhtar Nebab:1)Department of Civil Engineering, Faculty of Technology, University of M
Abstract
This study shows functionally graded material structural topology optimization under buckling constraints. The
SIMP (Solid Isotropic Material with Penalization) material model is used and a method of moving asymptotes is also employed
to update topology design variables. In this study, the quadrilateral element is applied to compute buckling load factors. Instead
of artificial density properties, functionally graded materials are newly assigned to distribute optimal topology materials
depending on the buckling load factors in a given design domain. Buckling load factor formulations are derived and confirmed
by the resistance of functionally graded material properties. However, buckling constraints for functionally graded material
topology optimization have not been dealt with in single material. Therefore, this study aims to find the minimum compliance
topology optimization and the buckling load factor in designing the structures under buckling constraints and generate the
functionally graded material distribution with asymmetric stiffness properties that minimize the compliance. Numerical
examples verify the superiority and reliability of the present method.
Key Words
buckling constrains; Finite Element Method; functionally graded materials; topology optimization
Address
Minh-Ngoc Nguyen:Department of Architectural Engineering, Sejong University, Seoul, 05006, Republic of Korea
Dongkyu Lee:Department of Architectural Engineering, Sejong University, Seoul, 05006, Republic of Korea
Soomi Shin:Research Institute of Industrial Technology, Pusan National University, Busan, 46241, Republic of Korea
