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CONTENTS
Volume 99, Number 6, September25 2026
 

Abstract
The accumulation of discarded filters in natural environments contributes significantly to environmental pollution and adversely affects both terrestrial and aquatic ecosystems, posing threats to human health and biodiversity. This study aims to evaluate the feasibility of incorporating ash derived from these filters into mortar characteristics that include silica fume. Various mechanical proportions of filter ash were systematically integrated into themortarmatrix, and the resulting mechanical properties—specifically, specific weight, compressive strength, modulus of elasticity, and tensile strength under bending—were assessed across different experimental designs. Laboratory analysis showed that the use of ash from cigarette butts, up to a maximum of 5%, enhances the mechanical performance of the mortar. Specifically, the optimal mixture containing 5% cigarette butt ash (CBsA) yielded a 5% increase in 28-day compressive strength, a 32% increase in modulus of elasticity (from 24.3 GPa to 32.0 GPa), and a 48% increase in 28-day flexural bending strength compared to the control mix without ash. Furthermore, this optimal design exhibited the highest energy absorption capacity under bending loads among all tested formulations.Additionally, the study presents the results of diffraction tests and electronicmicroscopy images, which provide insights into the optimal design and control samples.

Key Words
ash from cigarette butts; bending strength; compressive strength; scanning electron microscopy; X ray diffraction analysis

Address
Mehdi Rezaie, Hamid Reza Ahmadi, Javad Barfi Bookat: Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh 55136-553, Iran

Abstract
Energy-based seismic damage models are widely used to represent cumulative deterioration in reinforced concrete (RC) elements under cyclic loading. Among them, the Park-Ang model remains influential because it combines peak deformation demand and cumulative hysteretic energy dissipation within a unified scalar framework. However, its conventional use relies on a globally constant energy-weighting coefficient, implicitly assuming that deformation-energy interaction remains invariant over nonlinear response levels. This study proposes a codecompatible bounded deformation-energy damage index for RC elements. The methodology integrates nonlinear moment-curvature analysis, confinement-sensitive sectional modeling, capacity-based cyclic loading simulations, hysteretic energy computation, energy-equivalent target construction, and leakage-free grouped cross-validation. Instead of treating the Park-Ang coefficient as the final calibrated model, the framework derives energy-based damage targets from code-based deformation performance regions and represents them through a compact bounded response surface in the normalized deformation-energy space. The procedure is formulated in a code-compatible manner and can be adapted to seismic assessment frameworks that define deformation-based limit states. The results demonstrate improved continuous damage prediction, residual consistency, error-distribution behavior, and performance-state agreement relative to Park-Ang-type baselines. Local energy-sensitivity diagnostics indicate that cumulative hysteretic energy contributes to damage in a response-dependent manner. The proposed framework provides a physically bounded, interpretable, and code-compatible basis for continuous energy-based seismic damage assessment.

Key Words
bounded damage index; code-compatible assessment; deformation-energy interaction; hysteretic energy dissipation; Park-Ang model; performance-based earthquake engineering; reinforced concrete; seismic damage index

Address
Arif Hüseyin Ayabakan: Department of Civil Engineering, Gebze Technical University, Kocaeli, Türkiye
Ahmet Anil Dindar: MARTEST Research Center, Gebze Technical University, Kocaeli, Türkiye

Abstract
Despite improving land-use efficiency, double-deck depots have seen limited adoption due to vibration concerns. This paper presents the first field test study on train-induced vibrations in prototypical frame-supported superstructures above a double-deck metro depot. The research evaluated the structural performance of a super-tall shear wall building, a high-rise shear wall building, a high-rise shear wall building with inter-story isolation, and a multi-story frame building, considering multiple vibration attenuation measures including track-based solutions and inter-story isolation. The test results show that Vibration levels are strongly correlated with superstructure type, following a descending order from the multi-story frame to the super-tall shear wall, the high-rise shear wall, and finally the isolated high-rise shear wall structure. Indoor structure-borne noise showed a strong correlation with structural vibration. The mitigation measures proved highly effective in suppressing the propagation of vibrations, confirming the vital role of inter-story isolation for vibration attenuation of the high-rise superstructure. This study confirms that the vibration issue in high-density developments above double-deck depots is technically controllable, offering a technical reference for promotion application.

Key Words
double-deck metro depot; frame-supported structure; in-situ test; metro induced vibration; vibration mitigation measure

Address
Yangyang Chen: Earthquake Engineering Research and Test Center, Guangzhou University, Guangzhou, 510006, China; Key Laboratory of Earthquake Resistance, Earthquake Mitigation and Structural Safety, Ministry of Education, Guangzhou University, Guangzhou, 510006, China; Guangdong Provincial Key Laboratory of Earthquake Engineering and Applied Technology, Guangzhou University, Guangzhou, 510006, China
Zixuan Chen: Earthquake Engineering Research and Test Center, Guangzhou University, Guangzhou, 510006, China; Key Laboratory of Marine Civil Engineering Materials and Structures, Ministry of Education, Jinan University, Guangzhou, 510632, China
Zhenyu Yang: Earthquake Engineering Research and Test Center, Guangzhou University, Guangzhou, 510006, China; Key Laboratory of Earthquake Resistance, Earthquake Mitigation and Structural Safety, Ministry of Education, Guangzhou University, Guangzhou, 510006, China; Guangdong Provincial Key Laboratory of Earthquake Engineering and Applied Technology, Guangzhou University, Guangzhou, 510006, China
Wei Zhao: Key Laboratory of Marine Civil Engineering Materials and Structures, Ministry of Education, Jinan University, Guangzhou, 510632, China
Chenhao Zhong: Earthquake Engineering Research and Test Center, Guangzhou University, Guangzhou, 510006, China; Key Laboratory of Earthquake Resistance, Earthquake Mitigation and Structural Safety, Ministry of Education, Guangzhou University, Guangzhou, 510006, China; Guangdong Provincial Key Laboratory of Earthquake Engineering and Applied Technology, Guangzhou University, Guangzhou, 510006, China
Zhongling Xiao: Earthquake Engineering Research and Test Center, Guangzhou University, Guangzhou, 510006, China; Guangzhou City Construction & Development Co., Ltd., Guangzhou, 510623, China

Abstract
To ensure the structural safety of critical infrastructure such as nuclear power plants, it is essential to accurately predict the occurrence and extent of scabbing caused by collisions. However, the reliability of numerical analysis results is limited by uncertainties in uncertain parameters related to materials, manufacturing, and equipment errors. This study aims to identify the major factors to be considered in collision analysis. To fulfill this objective, the sensitivity of the two response ratios (residual velocity ratio and scabbing area ratio) to seven uncertain parameters within realistic variation ranges was quantitatively evaluated. Based on optimal modeling techniques validated through previous research, collision analysis was performed using the general-purpose finite element analysis program, LS-DYNA. Screening of main effects was conducted using a statistical analysis method, fractional factorial design (FFD), and a single-variable sensitivity analysis was applied to the major factors. Analysis results confirmed that concrete compressive strength and impact angle were the major factors for both responses, and the yield strength of rebars was the additional major factor for the ratio of residual velocity. One-factor-at-a-time (OFAT) sensitivity analyses were performed on the two variables identified as major factors to both responses in the FFD, and the results confirmed a statistically significant trend. For the analysis of impact angles, excluding data of normal impacts significantly improved the fit and statistical significance. Therefore, when analyzing the angle effect, cases involving normal collisions should be treated separately.

Key Words
collision analysis; fractional factorial design; reinforced-concrete panel; residual velocity; scabbing area; uncertain parameter

Address
Yeongjun Kim, Seongyeop Kim, Jungwhee Lee: Infrastructure and Construction Engineering, Dankook University, Yongin-si 16890, Republic of Korea
Hyukjun Ahn: Department of Civil & Environmental Engineering, Seoul National University, Seoul 08826, Republic of Korea

Abstract
This study evaluates alternative reinforcement strategies for a reinforced concrete arch bridge using a Digital Twin calibrated against modal measurements. Continuous structural health monitoring (SHM) revealed recurrent exceedances of longitudinal acceleration thresholds at one extreme column. Analysis showed short responses impulsively excited by heavy vehicles travelling at speed, with amplitudes governed by column resonance rather than solely by impact characteristics. Field inspection identified deterioration of the joint-deck interface near the southern abutment. As the alerts predated this finding, the defect is treated as an aggravating factor rather than the primary cause of the anomalous response, and the numerical models represent the interface in its restored condition. The calibrated model reproduced six identified modes with frequency errors below 3% and was used to assess the sensitivity of the slender columns and evaluate mitigation strategies. Four strengthening strategies were investigated: reinforced concrete jacketing, steel jacketing with transverse confinement collars, CFRP wrapping, and a hybrid solution. The assessment focused on the first longitudinal bending mode of the columns, at 5.73 Hz. Because the analysis is based on eigenvalue analysis and provides preliminary comparative results rather than detailed designs, conclusions are expressed in terms of modal properties and stiffness, not quantified reductions in operational vibration amplitudes. The integration of SHM data, threshold-based alerting, and Digital Twin simulations provides a framework for diagnosing dynamic anomalies and comparing reinforcement strategies before implementation. The approach supports decision-making based on structural behavior and can be extended to similar bridge systems.

Key Words
bridge reinforcement; digital twin; dynamic behavior; modal analysis; structural health monitoring

Address
Javier Maldonado, Teresa P. Real, Julia I. Real: Instituto de Matemática Multidisciplinar (IMM), Universitat Politécnica de València (UPV), Camino de vera s/n, Valencia, 46022, Spain
Anabel Arias: IDVIA 2020 Horizonte 2020 S.L., Plaza Bandas de Música 5, Local 11, Valencia, 46013, Spain

Abstract
This paper presents a new two-phase automated procedure for identifying yield line patterns and computing upper bound collapse loads for reinforced concrete (RC) slabs. Themethod builds upon a modified rigid finite element formulation previously proposed by the author but extends it into an iterative algorithm in which displacement contours froman initial analysis are used to construct a refined, problem-specificmesh alignedwith the evolving collapse mechanism. This displacement driven remeshing strategy eliminates the need for predefined yield line patterns, significantly reducing the solution space while preserving kinematic admissibility. The approach provides accurate upper-bound estimates within a small number of iterations and exhibits low sensitivity to the starting mesh. A series of benchmark and irregular slab examples demonstrates the accuracy, robustness, and computational efficiency of the method, including comparisons with Discontinuity Layout Optimisation (DLO) and best-known analytical solutions. The results highlight the potential of the proposed procedure as an automated and efficient tool for the collapse analysis of reinforced concrete slabs.

Key Words
linear programming; slabs and plates; yield line analysis

Address
Husham Ahmed: Amentum (UK) Ltd., 105 Summer Street, London SE1 9HZ, UK

Abstract
The dynamic behavior of porous functionally graded (FG) graphene platelet-reinforced composite plates under moving loads is investigated, with a focus on the combined effects of variable thickness and bidirectional edge constraints. While previous studies have examined moving-load problems, they have generally assumed constant thickness and conventional edge conditions, leaving a significant gap in understanding more complex geometric configurations. This study addresses that gap by developing a nonlinear dynamic model for plates featuring doublevariable-edge and variable thickness (DVEVT). The governing equations are formulated within the framework of the first order shear deformation theory (FSDT), with material properties estimated using the Halpin-Tsai micromechanical model. Assuming simply supported boundaries, the equations of motion are discretized via the Galerkin method and solved numerically using the fourth-order Runge-Kutta numerical method (RK4). A convergence study is first conducted on the central dynamic deflection to ensure numerical accuracy. Extensive parametric analyses are then performed to elucidate the influences of material parameters (such as GPL distribution and porosity), geometric parameters (variable thickness and bidirectional edge constraints), load characteristics (velocity and magnitude), thermal effects, and elastic foundation stiffness on the nonlinear dynamic response. The results reveal that the interplay of variable thickness and bidirectional constraints significantly alters the plate's vibration characteristics, providing new insights for the design of advanced lightweight structures subjected to moving loads.

Key Words
double-variable-edge; DVEVT plates; dynamic response; moving load; RK4

Address
Gui-Lin She, Zhen-Xi Qi: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

Abstract
This study investigates 2D axisymmetric Multi-Material Arbitrary Lagrangian-Eulerian (MM-ALE) mapping approaches for EFP analysis to achieve computational efficiency while maintaining accuracy. Using LSDYNA, three modeling methods were evaluated: MM-ALE (Model 1), hybrid MM-ALE Lagrangian interaction (Model 2), andMM-ALE using structuredmesh (Model 3). 2D axisymmetric analysiswas performed untilmetal jet impact, followed by 3Dmapping for penetration analysis. Results showthat the 2D axisymmetricmodels accurately predict the maximum jet velocity within a 2.1% deviation compared to the full 3D MM-ALE analysis, while capturing overall jet shape trends. CPU time comparison reveals 2D mapping analysis is approximately 4.89 times faster than full 3DMM-ALE analysis. The mapping approach provides comparable accuracy to full 3DMM-ALE analysiswhile significantly reducing computational cost,making it practical for EFP impact analysis.

Key Words
2D axisymmetric ALE; 3D MM-ALE; Explosively Formed Projectile (EFP); LS-DYNA

Address
Hwa Jung Kim, Min-kyu Kim, Ihn Soo Kim, Ho Bum Kim: R&D Center, Hyundai-Rotem, Uiwang-si, Gyeonggi-do 16082, South Korea
Heonyong Lim: Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea

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