Abstract
The current paper aims to present an active control procedure for optimally minimizing the dynamic response of functionally graded plates in various edge conditions. The plates are reinforced by four distribution types of uniaxially aligned straight carbon nanotubes in the through-thickness plate direction. The plates are subjected to an
active force distributed on the upper face; this force is taken as a control tool for the minimization process. The plate governing equations are derived based on a higher-order plate theory, and the target function is formulated including the plate total energy as a measure for the dynamic response and the control energy according to the Pareto principle. The control problem is solved using the Lyapunov-Bellman theory. Numerical analyses are presented to examine the given control procedure's efficiency and illustrate the influence of reinforcement type, the order of the plate theory, boundary conditions, and volume fractions on the control process. To the best of our knowledge, this study represents one of the first implementations of a Lyapunov–Bellman theory for carbon nanotube reinforced plates.
Key Words
control; dynamic response; FG plates; nanotubes; reinforcement
Address
Elhadi E. Elamir, M. Alqhtani, H. Alhadad, Mahmoud A. Abdelaziz, Alhanoof D. Alhareth: Department of Mathematics, Najran University, Najran, 1988, Saudi Arabia
Abstract
The reinforced railway embankments traversing fault zones are susceptible to severe seismic damage, which could disrupt normal railway operation. This paper investigates the seismic response of reinforced railway embankment situated in a fault zone in China. The seismic response characteristics of reinforced railway embankment under strike-slip and reverse fault movement are investigated by means of shaking table tests and 3D numerical simulations. A dual-shaking table test was employed to simulate different seismic loading on either side of the fault, and a full-scale numerical model was established by using FLAC3D software. The results between shaking table test and numerical simulation are compared in terms of the acceleration amplification effects, horizontal displacements, and settlement behavior of the foundation. It is indicated that the impact of strike-slip fault motion on embankment is considerably more significant than that of reverse fault motion. The horizontal acceleration is the most amplified at the midpoint of slope, while the amplification effect of vertical acceleration is mostly observed at the base of slope. The amplification coefficient decreases non-linearly as the earthquake magnitude increases. Strikeslip fault motion leads to asymmetric displacement and tilting on both sides of the embankment, while reverse fault motion causes differential settlement along the railway alignment.
Key Words
crossing-fault; numerical simulation; reinforced embankment; shaking table test
Address
Zhiyi Cong: School of Civil Engineering, Central South University, Changsha, 410075, China; National Engineering Research Center of High-speed Railway Construction Technology, Central South University, Changsha, 410075, China
Chao Cao: China Construction Fifth Engineering Bureau Co. Ltd., Changsha, 410019, China
Yuliang Lin: School of Civil Engineering, Central South University, Changsha, 410075, China; National Engineering Research Center of High-speed Railway Construction Technology, Central South University, Changsha, 410075, China
Xiaojing Li: China Construction Fifth Engineering Bureau Co. Ltd., Changsha, 410019, China
Hongri Zhang: Guangxi Transportation Science and Technology Group Co. Ltd., Nanning, 530029, China
Guolin Yang: School of Civil Engineering, Central South University, Changsha, 410075, China
Abstract
This paper aims to study the static and free vibration analysis of porous functionally graded (PFG) plates with different boundary conditions. Two different FGM models for material properties of PFG plate are graded by the rule of mixture (P-FGM) and sigmoidal rule (S-FGM), through the thickness direction of the plate. Plate kinematics are defined by using first-order shear deformation plate theory (FSDPT) to analyze the static behavior based on numerical technique, finite element method (FEM). Also, a four-node quadrilateral plate element with five degrees of freedom at each node has been used during FEM analysis. The governing equations of porous FG plates are developed using variational principles, considering various types of porosity distribution patterns. Moreover, two types of transverse loads including uniformly distributed and sinusoidal loads are considered. The numerical illustrations are presented for static analysis of the PFG plate having two different constituent materials. The accuracy of the present technique is ascertained by comparing the numerical results with available findings in the literature. Then, the effect of aspect ratio, length-to-thickness ratio, porosity parameter, various boundary conditions and power law index on the bending and vibration response of PFG plate are examined to explore the scope of the study. Ultimately, the results of this study provide new avenues for the design and optimisation of novel PFG plate structures and further understanding of the mechanical behaviour of FGMs.
Key Words
FEM; FSDPT; functionally graded material; porosity; power law function; sigmoid law
Address
Vineet Kumar: Mechanical Engineering Department, Engineering College, Bikaner, India
S.J. Singh: Mechanical Engineering Department, NSUT, New Delhi, India
S.P. Harsha: Advance Vibration Laboratory, Mechanical & Industrial Engineering Department, IIT Roorkee, India
Abstract
This study estimates the TNT equivalency of the commercial high explosive MegaMEX and evaluates the applicability of CONWEP-based blast modeling for fully vented internal explosions in nuclear facilities. Empirical blast-load models rely on TNT equivalency. However, uncertainties arise when non-TNT commercial explosives are involved and when explosions occur in internal environments. To address these issues, the TNT equivalency of MegaMEX was estimated using heat-based and detonation velocity-based scaling methods. Numerical simulations were performed using LS-DYNA with the CONWEP-based LBE card and validated against experimental measurements of peak overpressure and positive-phase impulse from a fully vented internal explosion test. Although originally developed for free-field detonations, the LBE card demonstrated reasonable accuracy under fully vented internal blast conditions. Among the scaling methods, the detonation velocity-based approach showed the closest agreement with experimental data. These results indicate that detonation velocity-based scaling provides a practical characterization of MegaMEX and that the LBE card offers a computationally efficient approach for internal explosion analysis in nuclear facilities.
Key Words
CONWEP; internal explosion; LBE; LS-DYNA; MegaMEX; TNT equivalency
Address
Seunggyu Lee: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Sungbo Lee: Gen-IV Reactor Technology Development Division, Korea Atomic Energy Research Institute, 989 Daedeok-daero, Yuseong-gu, Daejeon 42057, Republic of Korea
Phill-Seung Lee: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Abstract
Circular hollow sections (CHS) are widely used in modern structures because of their lightweight and aesthetic appearance. CHS can be found as a truss chord receiving connections from other branch members. Literature is rich with research on the behavior of connections using a single branch plate (SBP). Also, design rules are available in international codes to calculate the capacity of this type of connection, depending on the branch plate orientation and the type of loads transmitted to the chord. Few studies have been conducted on the connection with double branch plates (DBP) to rectangular or square hollow sections, aiming to enhance the connection behavior and increase its capacity; however, it is still not studied for CHS and is not covered in the design codes. This paper investigates the behavior of longitudinal DBP under axial load to the CHS chord in a T-joint. For this study, a nonlinear finite element analysis is performed using ABAQUS software. The geometry of the DBP in terms of plate thickness, length, and spacing are studied. The results are compared to the available design rules for connections having SBP. The failure modes are presented, and the effects of the different parameters are studied. The paper ends with a proposal to calculate the capacity of longitudinal DBP, showing a greater capacity than the common SBP.
Key Words
axial load; branch plates; finite element modeling; hollow sections; T-joint
Address
Omar Atya, Ahmed A. Matloub, Mohamed A. Abokifa, Ahmed H. Yousef: Department of Structural Engineering, Ain Shams University, Cairo, Egypt
Abstract
The seismic responses of the embedded traffic signal poles are examined with an emphasis on the influence of soil mechanical properties on deformation mechanisms in this study. A three-dimensional finite element model was developed, and monotonic, cyclic, and nonlinear time-history analyses were conducted for three foundation boundary conditions: fixed-base, well graded sand (SW), and clayey sand (SC). For the SW soil and SC soil, the initial lateral stiffness decreased approximately 8% and 17% compared to the fixed-base condition, which indicates the governing role of soil flexibility in early-stage response. Under monotonic loading, significant soil opening occurred at drift ratios of approximately 1.8% and 2.2% in SW and SC soil, respectively, demonstrating that cohesion delays separation but leads to rapid stiffness loss once mobilized. Cyclic analysis revealed that SW soil maintained mixed flexure–rotation behavior with gradual stiffness degradation, whereas SC soil transitioned rapidly to rotation dominated response due to cohesion degradation and interface slip. Additionally, time-history results further showed that the fixed-base condition underestimated displacement demands. The SW case showed relatively consistent displacement responses under different ground motions, and the SC case showed obvious variability and larger drift demand under strong ground motions. The investigation results show that the seismic response of traffic signal poles is significantly influenced by supporting soil conditions. In particular, depending on the soil stiffness and cohesion properties, the traffic signal pole exhibits different responses, resulting in flexure-dominated or rotationdominated seismic behavior and associated damage mechanism.
Key Words
finite element analysis; seismic responses; soil-structure interaction; traffic signal pole; transport infrastructures
Address
Taehyeon Kim: Department of Civil Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea
Jong-Han Lee: Department of Civil Engineering, Inha University, Incheon 22212, Republic of Korea
Yu-Chen Ou: Department of Civil Engineering, National Taiwan University, Taipei 10617, Taiwan
Hwasung Roh: Department of Civil Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea
