Abstract
In this work, the effect of the correction fibers direction on the efficiency of repairing damaged composite plates was
highlighted. The composite plates studied in this work consist of eight layers of graphite/epoxy, while the patch used in this repair consists of four layers of the same type. The results obtained in this work, whether with regard to the experimental or analytical side, showed that the fibers orientation affects the repair efficiency, so the closer the angle of fibers inclination is to the tensile strength direction, the performance of the composite material is ideal. Hence, we conclude that the composite materials with longitudinal fibers (Parallel to tensile strength) is the most powerful and efficient material in performance.
Key Words
composite; laminate; stacking sequence; stress intensity factor (SIF); the damaged area ratio (DR); ultimate
strength
Address
Berrahou Mohamed: University of Relizane, GIDD Laboratory, Relizane 48000, Algeria; University of DJILLALI LIABES, LMPM Laboratory, Sidi Bel Abbes 22000, Algeria
Amari Khaoula: University of USTO, LAPS Laboratory, Oran 31000, Algeria
Belkaddour Leila, Serier Mohamed: University of Relizane, GIDD Laboratory, Relizane 48000, Algeria
Abstract
This study investigates the effectiveness of tuned mass dampers (TMDs) in controlling vibrations in low-rise reinforced concrete buildings. It examines both linear and nonlinear behaviors of concrete structures subjected to strong ground motions from the PEER database. The research follows the ASCE 7-16 provisions to model structural nonlinearity. Additionally, the study explores the effect of varying TMD mass ratios on the performance of these systems in real-world conditions. The findings emphasize the importance of accounting for structural nonlinearity in low-rise buildings, highlighting its significant influence on the controlled response under severe seismic excitations. The study suggests including nonlinear analysis in seismic design practices and recommends customizing TMD designs to optimize vibration control. These recommendations have practical implications for enhancing the safety and effectiveness of seismic design practices for low-rise buildings.
Key Words
low-rise buildings; seismic design; structural nonlinearity; tuned mass damper; vibration control
Address
Abbas Bigdeli: StruTechnology, Gasan-Dong Geumcheon-Gu, Seoul 08502, Republic of Korea
Md. Motiur Rahman: Department of Civil Engineering, Pabna University of Science and Technology, Pabna 6600, Bangladesh
Dookie Kim: Department of Civil Engineering and Environmental Engineering, Kongju National University,
Cheonan-si, Chungcheongnam-do 31080, Republic of Korea
Abstract
This paper developed and examined a novel passive vibration isolator (i.e., "X-inerter") motivated by combining a bio-inspired structure and a rack-pinion inerter. The bio-inspired structure provided nonlinear stiffness and damping owing to its geometric nonlinearity. In addition, the behavior was further enhanced by a gear inerter that produced a special nonlinear inertia effect; thus, an X-inerter was developed. As a result, the X-inerter can achieve both high-static-low-dynamic stiffness (HSLDS) and quasi-zero stiffness (QZS), obtaining ultra-low frequency isolation. Furthermore, the installed inerter can produce a coupled nonlinear inertia and damping effect, leading to an anti-resonance frequency near the resonance, wide isolation region, and low resonance peak. Both static and dynamic analyses of the proposed isolator were conducted and the structural parameters' influence was comprehensively investigated. The X-inerter was proven to be comparatively more stable in the ultra-low frequency than the benchmarking QZS isolator due to the nonlinear damping and inertia properties. Moreover, the inertia effect could suppress the bio-inspired structure's super- and sub-harmonic resonance. Therefore, the X-inerter isolator generally possesses desirable nonlinear stiffness, nonlinear damping, and unique nonlinear inertia, designed to achieve the ultra-low natural frequency, the anti-resonance property, and a wide isolation region with a low resonance peak.
Key Words
high-static-low-dynamic stiffness; nonlinear inerter; superharmonic resonance; vibration isolation
Address
Jing Bian, Xu-hong Zhou, Ke Ke, Yu-hang Wang: School of Civil Engineering, Chongqing University, Chongqing, China;
Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing, China
Michael CH Yam: Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China; Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), The Hong Kong Polytechnic University, Hong Kong, China
Yue Qiu: Grimwade Centre for Cultural Materials Conservation, School of Historical and Philosophical Studies, Faculty of Arts, The University of Melbourne, Parkville, Australia
Abstract
The Radial Point Interpolation Method (RPIM) has been proposed to overcome the difficulties associated with the
use of the Radial Basis Functions (RBFs). The RPIM has the following properties: Simple implementation in terms of boundary conditions as in the Finite Element Method (FEM). A less expensive CPU time compared to other collocation meshless methods such as the Moving Least Square (MLS) collocation method. In this work, we propose an adaptive high-order numerical algorithm based on RPIM to simulate the thermoviscoplastic behavior of a material mixing observed in the Friction Stir Welding (FSW) process. The proposed adaptive meshfree RPIM algorithm adapts well to the geometric and physical data by choosing a good shape parameter with a good precision. Our numerical approach combines the RPIM and the Asymptotic Numerical Method (ANM). A numerical procedure is also proposed in this work to automatically determine an improved shape parameter
for the RBFs. The efficiency of the proposed algorithm is analyzed in comparison with an iterative algorithm.
Key Words
homotopy continuation method; meshless collocation method; optimization technique; radial point interpolation method; shape parameter; thermoviscoplastic material
Address
Zouhair Saffah: LIMAT Laboratory, Faculty of Sciences of Ben M
Abstract
This paper presents a method for assessing the dynamic responses of gravity-based structures (GBS) under various
seismic loads, with a focus on fluid-structure-ground interactions. Models of GBSs and their surrounding environments were developed, incorporating interaction effects among the structure, seawater, and seabed. Dynamic responses of the GBS subjected to three seismic loads—Chi-Chi, Northridge01, and Northridge02—were calculated, with consideration of both horizontal and vertical accelerations, as well as displacements. Parametric studies indicated that the primary factors affecting the dynamic responses of GBS were seismic loads characterized by significant input forces and accelerations. The frictional force on the ground had minimal impact on the horizontal and vertical displacements of the GBS. Weight emerged as a critical factor in anchoring the GBS to the ground and minimizing vertical accelerations and displacements.
Key Words
gravity-based structure; fluid-structure-ground interaction; dynamic analysis; seismic loads
Address
Hyo-Jin Kim: Center for Healthcare Robotics, Korea Institute of Science and Technology, 14 Hwarang-ro, Seongbuk-gu, Seoul 02792, Republic of Korea
Sunghun Jung: Ship & Offshore Research Institute, Samsung Heavy Industries, 23 Pangyo-ro 227, Bundang-gu, Seongnam-si, Gyeonggi 13486, Republic of Korea
Seongpil Cho: School of Aerospace and Mechanical Engineering, Korea Aerospace University, 76 Gonghangdaehak-ro, Deokyang-gu, Goyang-si, Gyeonggi 10540, Republic of Korea
Abstract
Base isolation is a widely used technique for the seismic control of structures as it reduces the structural seismic demand. However, displacement of the isolation layer is not economically feasible in congested urban areas. To resolve the issue, an innovative system is proposed here to isolate both horizontally at the base and vertically in the upper portion of the structure. A simplified linear three degree-of-freedom (3DOF) model of the system that considers the mass and stiffness ratios of the substructure has been introduced and analyzed in MATLAB by spectrum analysis. The 3DOF model results revealed that, when the period of the soft substructure reaches 2.5 times that of the stiff substructure, the isolation and the lower substructure responses decrease by 65% and 51%, respectively. Time-history analysis of a MDOF system at three frequency ratios under a wide range of ground motions indicated that, at the expense of accepting a certain large drift by the soft substructure in the upper portion of the structure, base isolation displacement can be decreased by 10%.
Key Words
base isolation; dual isolation; response spectra; structural control; time-history analysis; vertical isolation
Address
Sasan Babaei, Panam Zarfam: Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Abdolreza Sarvghad Moghadam: Structural Engineering Research Center, International Institute of Earthquake Engineering and Seismology, Tehran, Iran
Seyed Mehdi Zahrai: School of Civil Engineering, College of Engineering, University of Tehran, P.O. Box 11155-4563, Tehran, Iran; Civil Engineering Department, University of Ottawa, Canada
Abstract
This study examines how the interaction between soil and a wind turbine's supporting system affects the optimal design. The supporting system resting on an elastic soil foundation consists of a steel conical tower and a concrete circular raft foundation, and it is subjected to wind loads. The material cost of the supporting system is aimed to be minimized employing various metaheuristic optimization algorithms including teaching-learning based optimization (TLBO). To include the influence of the soil in the optimization process, modified Vlasov and Gazetas elastic soil models are integrated into the optimization algorithms using the application programing interface (API) feature of the structural analysis program providing two-way data flow. As far as the optimal designs are considered, the best minimum cost design is achieved for the TLBO algorithm, and the modified Vlasov model makes the design economical compared with the simple Gazetas and infinitely rigid soil models. Especially, the optimum design dimensions of the raft foundation extremely reduce when the Vlasov realistic soil reactions are included in the optimum analysis. Additionally, as the designated design wind speed is decreased, the beneficial impact of soil interaction on the optimum material cost diminishes.
Abstract
This article describes experimental and numerical analyses of eccentrically loaded over the axially loaded circular concrete filled double-skinned steel tubular (CFDST) short columns. Tests on circular CFDST short columns under eccentric and concentric loading were conducted to assess their responses to the frequent intensity of 5–30 mm at the interval of each 5 mm eccentric loading conditions with constant cross-sectional proportions and width-to-thickness ratios of the outside and internal tubes. The non-linear finite-element analysis of circular CFDST short columns of eccentrically loaded over the axially loaded was performed using the ABAQUS to predict the structural behavior and compare the concentric loading capacity over the various eccentric loading conditions. The comparison outcomes show that the axial compressive strength of the circular CDFST short columns was 2.38–32.86%, lesser than the concentrically loaded short column with the inner circular section. Also, the influence of computer simulation employed is more efficient in forecasting the experimentally examined performance of circular CFDST stub columns.
Address
Manigandan R.: Department of Civil Engineering, Saveetha School of Engineering, (SIMATS), Chennai, Tamil Nadu, 602 105, India
Manoj Kumar: Department of Civil Engineering, Birla Institute of Technology and Science, Pilani (BITS Pilani), Vidya Vihar, Rajasthan 333 301, India
