Abstract
This study investigates the effectiveness of the sliding sector controller (SSC) for the design of a smart base-isolation system composed of a low-damping linear base-isolation and a magneto-rheological (MR) damper. The SSC strategy based on the variable structure controller is defined by an appropriate sliding sector with its respective control laws. In this study, the smart base-isolation system of an isolated four-story shear building is first designed using the SSC strategy under an artificial earthquake excitation. For this purpose, the required voltages of the MR damper is determined using the SSC strategy and clipped-optimal control algorithm. Then, the seismic performance of the designed smart base-isolation using the SSC strategy is
evaluated in mitigating the displacement of isolator and the structural responses under four real earthquake excitations. Further, the efficiency of the SSC strategy is compared against that of two states of the MR damper (i.e., passive-off and passive-on). Results indicate the effectiveness of the SSC strategy in designing the smart base-isolation system which can provide the simultaneous reduction of the maximum displacement of isolator and structural responses under real earthquakes. In addition, comparative results demonstrate that the SSC strategy requires less electric energy than the passive-on strategy, while two strategies achieve about similar dissipated energy and maximum damper force.
Key Words
magneto-rheological damper; semi-active control; sliding sector; smart base-isolation; variable structure control
Address
Mohsen Khatibinia: Department of Civil Engineering, University of Birjand, Birjand, Iran
Hussein Eliasi: Department of Electrical Engineering, University of Birjand, Birjand, Iran
Alireza Gholibeygi: Department of Civil Engineering, University of Birjand, Birjand, Iran
Abstract
Accurately and efficiently establishing the multi-scale finite element (FE) model of a cable-stayed bridge remains
challenging. This study proposes a high-performance multi-objective model updating strategy to improve the accuracy and efficiency in calibrating a cable-stayed bridge's multi-scale FE model. The strategy employs the Kriging model performing global sensitivity analysis and model updating to reduce computational cost, and defines global and local multi-objective functions to improve the model's accuracy. The proposed approach is validated using a high-speed railway cable-stayed bridge. The bridge's global and multi-scale models are established and updated using the field-measured displacement, strain, and frequency. The results demonstrate that the proposed strategy delivers both high accuracy and markedly reduced computational overhead. The defined global and local objective functions avoid the determination of weighting factors and provide accurate
updating results. The Kriging model enhances the computational efficiency. Compared to the global FE model, the multi-scale model more accurately predict the critical main girder's behavior. After model updating, the maximum displacement error between the multi-scale model predicted and the experimental measured is under 10%, and that of stress and frequency are under 9% and 6%, respectively.
Key Words
cable-stayed bridge; finite element model updating; global sensitivity analysis; inverse problems; Kriging model; multi-objective functions
Address
Shiqiang Qin: School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, Hubei, China
Renxian Song: School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, Hubei, China
Yonggang Yuan: School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, Hubei, China
Shiwei Li: China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063, Hubei, China; China Railway 23rd Bureau Group Co., Ltd., Chengdu 610072, Sichuan, China
Yun-Lai Zhou: State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, Shaanxi, China
Abstract
This paper investigates the free vibration, nonlinear resonance, and low-velocity impact behavior of carbon nanotubereinforced composite (CNTRC) doubly-curved shells under hygrothermal environmental conditions. The primary research methodology and objectives are outlined as follows: (1) Dynamic modeling: Effective material properties of the composite, with carbon nanotubes as the reinforcement phase, are derived using composite inclusion theory. The displacement field of the doubly-curved shell is represented using Reddy's higher-order shell theory, establishing the dynamic model for the CNTRC doubly-curved shells. (2) Nonlinear free vibration: The Galerkin method is then employed to discretize these differential equations, enabling the investigation of the shell's free vibration characteristics. (3) Nonlinear main resonance: Incorporating
external excitation, the governing equations for forced nonlinear vibration are formulated. These equations are solved using the modified Lindstedt-Poincaré (MLP) method to obtain a second-order approximate solution characterizing the amplitudefrequency relationship. A parametric study examines the influence of various factors on the shell's nonlinear primary resonance. (4) Low-velocity impact response: The impact force expression is derived based on the nonlinear Hertzian contact law. The governing equations for low-velocity impact are subsequently obtained using the Euler-Lagrange principle. These equations are simplified via the Galerkin method and solved numerically using the Runge-Kutta method. The influence of key parameters on the low-velocity impact behavior is analyzed and discussed.
Key Words
carbon nanotube-reinforced composite; doubly curved shell; low-velocity impact response; nonlinear free vibration; nonlinear main resonance
Address
Jia-Qin Xu and Gui-Lin She: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing, 400044, China
Abstract
The study examined the pull-out behavior of crimped recycled fibers made from annealed and galvanized steel wires and compared it with commercial Dramix 4D fibers. These fibers were degraded in tap water and sodium chloride (NaCl) solutions with 3.5% and 7% concentrations. The objective was to evaluate how chloride-induced degradation affects the interfacial bond and mechanical performance of recycled steel fibers embedded in cement mortar. Unlike previous studies focused on commercial fibers, this work introduces recycled crimped fibers. It integrates pull-out, tensile, and compressive testing with SEM-EDS analysis to correlate corrosion with mechanical response. A total of 105 specimens were tested to determine maximum pull-out stress and toughness. Degradation tests were performed for 30 and 60 days, during which the compressive strength of mortars and the tensile strength of degraded fibers were also measured. Surface characterization was conducted by digital microscopy, Scanning Electron Microscopy (SEM), and Energy-Dispersive Spectroscopy (EDS). Annealed steel fibers showed the lowest corrosion resistance (8% mass loss), while galvanized fibers exhibited the highest (0.67%). After 30 days, chloride exposure caused slight mortar hardening and increased interfacial friction, raising pull-out forces for Dramix (=40%) and galvanized fibers (=7.5%). After 60 days, matrix weakening reduced adhesion and pull-out resistance, while the annealed steel fibers failed by rupture due to their high bond strength, with ductility decreasing up to 12.3%.
Key Words
crimped recycled fibers; degradation by water and chloride; mechanical properties; pull-out and compression; Steel Fiber Reinforced Concrete (SFRC)
Address
Oslery Becerra-Pérez, Alejandro Meza-de Luna: Department of Metal-Mechanical Engineering, Faculty of Engineering, Tecnológico Nacional de México/IT de Aguascalientes, Av. Adolfo López Mateos Ote. 1801, Bona Gens, 20256, Aguascalientes, Aguascalientes, México
Didilia Ileana Mendoza-Castillo, M.R. Moreno-Virgen: Department of Chemical Engineering, Faculty of Engineering, Tecnológico Nacional de México/IT de Aguascalientes, Av. Adolfo López Mateos Ote. 1801, Bona Gens, 20256, Aguascalientes, Aguascalientes, México
Abstract
This study presents an analytical formulation and numerical evaluation of flexural natural frequencies in clampedfree rectangular plates supported by inclined Euler–Bernoulli beams. Such structural configurations are frequently found in marine, aerospace, and civil engineering applications, particularly in systems such as ship bridge wings and cantilever platforms where vibration control is critical. Plates are modeled with classical Kirchhoff–Love theory, thereby considering a one-term Ritz approximation that satisfies the boundary conditions. Beam supports are modeled via the equivalent vertical stiffness derived from Euler–Bernoulli beam theory, which accounts for inclination effects and cross-sectional properties. The total energy of the system is formulated through energy methods, in which the strain and kinetic energy of the plate are combined with the stiffness contribution from the inclined beams. The natural frequencies are then extracted from the Rayleigh quotient. The model is solved for varying numbers of beams (n=2 to 5) and inclination angles (a=20o to 60o), and the first three flexural natural frequencies are computed. Unit consistency is carefully maintained by converting all the parameters to SI units. The results reveal that increasing the number of beams or reducing the inclination angle leads to increased stiffness levels and higher natural frequencies. The proposed formulation provides a compact and effective way to estimate natural frequencies at preliminary
design stages. It can also serve as a benchmark for validating finite element models and guiding structural optimization under vibration constraints.
Key Words
beam supported plates; energy methods; flexural vibrations; frame vibrations; modal analysis; plate theory
Address
Adil Yucel and Fulde Gunduz: Department of Mechanical Engineering, Istanbul Technical University, Inonu Cad. No. 65 Gumussuyu, Beyoglu, Istanbul, Türkiye
Abstract
This study explores the prediction of extreme structural responses in high-speed railway bridges using field-measured
displacement data and statistical analysis. One-month data collected from instrumented bridges in Korea are analyzed using two methods: the Gumbel probability paper and Peaks Over Threshold (POT) approaches. Extreme mid-span displacements for 100-and 200-year return periods are estimated, and statistical uncertainty is evaluated via bootstrap resampling. To assess long-term performance, synthetic one-year datasets are generated based on the short-term records. Results show that the Gumbel method
provides stable and consistent predictions, while the POT method is more sensitive to sample variability, particularly with limited data. However, both methods yield reliable estimates when sufficient data are available. This study offers practical insights into the application of extreme value theory for infrastructure monitoring and supports the development of data-driven strategies for resilient and sustainable bridge management.
Key Words
extreme response; field-measured data; gumbel probability paper; high-speed railway bridges; Peaks Over Threshold
Address
Doyoung Kim: Korea Research Institute for Local Administration, 21, Segye-ro, Wonju-si, Gangwondo, Republic of Korea
Eui-Seung Hwang, Bu-seog Ju, Sangwoo Lee: Department of Civil Engineering, Kyung Hee University, Yongin-Si, Gyeonggi-Do, Republic of Korea
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