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CONTENTS
Volume 37, Number 4, April 2026
 

Abstract
This research presents an experimental and numerical study on the behavior of rigid pavement slabs reinforced with different types of meshes under impact loading. The experimental program investigated several variables, including the effect of incorporating fiberglass as an additional reinforcement, along with different types and quantities of reinforcement meshes. These included low- and high-strength Gavazzi (glass fiber) meshes, expanded steel meshes, welded wire meshes, Tensar meshes, and Tenax meshes. Findings revealed that the use of reinforcement meshes—particularly the expanded mesh—led to a significant improvement in crack resistance. Notably, the number of impacts required to initiate the first crack increased from only 2 blows in the control specimen to 11 in the reinforced one, with the lowest corresponding crack displacement recorded at 0.14 mm. Furthermore, slabs reinforced with expanded mesh demonstrated the highest impact endurance until final failure, withstanding up to 90 blows, reflecting their high efficiency in enhancing structural performance under repeated impact loading. In terms of cost-effectiveness, the expanded mesh proved to be the most economical, with an average cost of EGP 2.89 per blow, followed by welded mesh at EGP 3.18. In contrast, Gavazzi meshes were the least economical, with a cost of EGP 6.37 per blow. Numerical modeling using Abaqus software showed good agreement with the experimental results in terms of failure modes and crack distribution. It also accurately represented both the displacement associated with the first crack and the final displacement at failure, thereby enhancing the reliability of the numerical model in studying the behavior of these slabs under impact loading.

Key Words
ferrocement slabs; Gavazzi mesh; geogrid; slag; steel mesh

Address
Mohamed Taha Abouelenain, Osama M. Moussa: Civil Engineering Department, Military Technical College, Cairo, Egypt
Yousry B. Shaheen: Civil Engineering Department, Faculty of Engineering, Menoufia University, Shebin El Koum, Egypt
Galal Elsamak: Civil Engineering Department, Faculty of Engineering, Kafrelsheikh University, Kafrelsheikh, Egypt
Ahmed Gamal Mahmoud Morsi: Civil Engineering Department, Benha Faculty of Engineering, Benha University, Benha, Egypt

Abstract
The pier-beam fixed system of bridges enhances structural stiffness and reduces positive flexural moment at the mid-span. However, as the structure of composite girder-pier fixed region is usually of large stresses and structural complexity, its mechanical performances usually need specific research. In this study, the structural behavior of the steel-concrete composite pier-girder fixed region of a specific continuous rigid frame bridge was investigated by experiment and numerical simulation. Notably, a scaled specimen with a 1/6 ratio was manufactured and loaded to assess its behavior. The nonlinear finite element model (FEM) analysis, considering material damage and steel-concrete interfacial bond-slip behavior, was then conducted to study the stress distribution, deformation, and bearing capacity. The experimental results show that the specimen remains within the elastic range under the 1.38 times of the design load, with no observed cracks in the concrete bridge deck or steel girder during the experimental loading process. The results obtained from the corresponding FEM, including the load-displacement curves, loadstress curves, stress distribution, agreed well with the experiment. Furthermore, the ultimate capacity of the pier-to-girder fixed region of the actual bridge was obtained by conducting nonlinear FEM analysis. The failure mode observed was the crack failure in the concrete bridge deck. When the load reaches 4.5 times of the design load, the fixed region cannot withstand additional load due to the instability propagation of concrete cracks. This study clarifies the stress characteristics of the fixed connection of the composite bridge and can provide some guidance for the design and analysis of similar structures.

Key Words
bridge engineering; composite beams; finite element analysis; load-bearing capacity; scale model test

Address
Miao Su, Hui Peng: 1) Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education (Changsha University of Science & Technology), Changsha 410114, Hunan, China; 2) School of Civil and Environmental Engineering, Changsha University of Science and Technology, Changsha 410114, Hunan, China
Guanyu Liu: School of Civil and Environmental Engineering, Changsha University of Science and Technology, Changsha 410114, Hunan, China
Yiyun Yang: 1) Key Laboratory of Safety Control of Bridge Engineering, Ministry of Education (Changsha University of Science & Technology), Changsha 410114, Hunan, China; 2) Zhongnan Survey and Design Institute Group Co., Ltd, Wuhan 430000, Hubei, China
Jianbo Yi: CCCC First Highway Engineering Group Co., Ltd, Lishui 323000, Zhejiang, China

Abstract
The durability of the reinforced cement concrete (RCC) structures exposed to open areas, i.e., bridges and marine structures, is affected by the chloride ions. The fly ash, silica fume, and ground granulated blast slag materials are used to reduce the chloride ions penetration. Still, the laboratory procedure for determining the chloride permeability is time-consuming and lengthy. This investigation introduces an optimal performance model to assess the chloride permeability of fly ash concrete. For that purpose, a database of chloride permeability results of 288 concrete specimens has been compiled from the literature. This research employs genetic and particle swarmoptimized relevance vector machine (RVM) models. Moreover, these RVM models have been configured by single and dual kernels. In addition, the extreme gradient-boosting (XGBoost) model has been developed and compared with RVM models. The performance comparison reveals that the RVM1 model has predicted chloride permeability with a performance index of 1.95, root mean square error of 286.8311C, a correlation coefficient of 0.9923, and the variance accounted for of 98.42 in the testing phase, close to the ideal values, followed by XGBoost model. The variance inflation factor (VIF) revealed that the binder and water-to-binder ratio features have considerable multicollinearity. This research also demonstrates that the database and structural multicollinearity highly influence the prediction capabilities of the RVM4 models. The score analysis, regression error characteristics curve, accuracy matrix, computational cost, and reliability analysis confirm that the RVM1 model is an optimal performance model in predicting the chloride permeability of fly ash concrete. This investigation will help concrete designers and engineers to determine the chloride permeability without performing laboratory procedures in mega construction projects.

Key Words
chloride permeability; dual kernel-based relevance vector machine; evolutionary algorithm; extreme gradient boosting; fly ash concrete

Address
Fatima Kechroud, Ali Benzaamia, Mohamed Ghrici: Geomaterials Laboratory, Department of Civil Engineering, University Hassiba Benbouali, P.O.Box 151, Chlef 02000, Algeria
Jitendra Khatti: Department of Civil Engineering, Rajasthan Technical University, Kota, Rajasthan, India

Abstract
This study investigates the nonlinear low-velocity impact response of functionally graded (FG) fluid-conveying pipes (FCPs), addressing critical gaps in existing research. Unlike prior studies on graphene-reinforced beams (Chen and She 2024), our work firstly incorporates fluid-structure interaction effects with graded material properties, enabling more accurate predictions for industrial pipeline systems. The key contributions include: (1) A novel analytical framework combining Euler beam theory, geometric nonlinearity, and fluid velocity coupling; (2) Systematic validation of damping effects on impact resilience, which previous studies have overlooked; (3) Demonstration that initial geometric imperfections exhibit a stronger influence on dynamic response than in homogeneous structures. Through Galerkin discretization and Runge-Kutta integration, we reveal parameter-sensitive regimes that could guide protective designs for high-speed fluid pipelines. These advancements distinguish our work by providing comprehensive solutions for FG materials under coupled mechanical and fluid dynamic loads.

Key Words
elastic foundations; fluid-conveying pipes; functionally graded; initial geometric imperfection; low-velocity impact

Address
College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

Abstract
This paper investigates the interfacial slip stresses in continuous steel-concrete composite beams reinforced with externally bonded composite plates. The study employs mathematical formulations to capture the nonlinear behavior of continuous composite beams, accounting for both equilibrium and deformation compatibility throughout all components of the reinforced structure. An analytical nonlinear modeling approach is developed alongside a finite element model to analyze interfacial slip in continuous composite beams. The results demonstrate that adhesive bonding between the concrete slab and steel beam can significantly reduce cracking in the negative moment regions of continuous beams. The theoretical and numerical predictions are validated through comparison with existing experimental and analytical results, enhancing the understanding of the mechanical behavior of continuous composite beams and informing the design of hybrid steel-concrete structures.

Key Words
adhesive bonding; analytical and a finite-element (FE) analysis; continuous steel-concrete beam; interfacial sliding stresses; shear deformations

Address
Hassaine Daouadji Tahar, Tayeb Bensatallah: 1) Department of Civil Engineering, Ibn Khaldoun University of Tiaret, Algeria; 2) Laboratory of Geomatics and Sustainable Development LGeo2D, University of Tiaret, Algeria
Boussad Abbes, Fazilay Abbes: Laboratory Materials and Mechanical Engineering MATIM, University of Reims, France

Abstract
Strengthening reinforced concrete (RC) beams using high-performance fiber-reinforced cementitious composite (HPFRCC) layer has emerged as an effective technique for structural retrofitting. This study investigates the flexural behavior of damaged RC beams strengthened with prefabricated HPFRCC layers through a combined experimental and three-dimensional finite element approach. Four-point bending tests were conducted on control and HPFRCC-strengthened beams to validate the numerical model. The validated model was then employed to assess the effects of pre-damage level (0-0.9Fu), HPFRCC layer thickness, and longitudinal reinforcement ratio (0.5-2.0%) on strength, stiffness, ductility, and energy absorption. The results indicate that HPFRCC strengthening can increase the yielding load by up to 36% and the ultimate flexural capacity by up to 25% for beams with moderate pre-damage levels, while improvements reduce to below 10% for severely damaged beams. The numerical results indicate that strengthening damaged reinforced concrete beams with prefabricated HPFRCC composites increased the ultimate flexural load by 28-42%, depending on the composite thickness and strengthening length. The initial flexural stiffness improved by up to 35%, while the mid-span deflection at ultimate load decreased by 18-25% compared to the unstrengthened damaged beams. In addition, the strengthened beams exhibited an increase in the ductility index from 2.1 to 3.4, accompanied by a 30% reduction in tensile damage concentration at the critical cracking zone.

Key Words
flexural capacity; HPFRCC layer; post-cracking behavior; RC beams

Address
Faculty of Engineering and Architecture, Department of Architecture, Kirşehir Ahi Evran University, Kirşehir, Türkiye

Abstract
In response to the growing importance of multi-asset option pricing, this study explores the three-asset Black-Scholes model and its practical applications in actuarial science. The governing partial differential equation presents computational challenges, which are addressed using two analytical iterative techniques—the variational iteration method and the variation of parameters method. The incorporation of the Lagrange multiplier reduces complexity and enhances convergence in the solution process. Numerical results are presented in graphical and tabular form using Maple software to facilitate interpretation and demonstrate the effectiveness of the proposed methods. The findings indicate that both techniques yield accurate and computationally efficient solutions. Overall, this work provides valuable insights into multi-asset option pricing and offers methodological tools that can be extended to other complex mathematical models. The methods and tools used in this study can be applied to other mathematical models and fields, thereby advancing the development of more accurate and efficient models.

Key Words
Black Scholes model; option pricing model; variational iteration method; variational parameter method and Lagrange multiplier

Address
Tayyab Zamir, Farooq Ahmed Shah: Department of Mathematics, COMSATS University Islamabad, Attock Campus, Pakistan
Ehsan ul Haq: Department of Mathematics, University of Wah, Pakistan

Abstract
This study investigates the latent relationship between ground motion parameters and seismic damage in reinforced concrete (RC) buildings using an unsupervised machine learning framework. A dataset comprising 21 seismic parameters from 466 ground motion records and the nonlinear response of 1,056 RC building models was analyzed. Unlike traditional regression-based studies, this research employs a "blind" learning approach to determine if clustering algorithms can autonomously identify physical damage mechanisms. The K-means algorithm, validated by K-fold cross-validation and internal indices, identified three distinct hazard categories. Crucially, the algorithm autonomously isolated a "Pulse-Like/Resonance-Critical" cluster driven by frequency-content parameters (Vmax/Amax and Tm) rather than simple peak intensity. Furthermore, Principal Component Analysis (PCA) revealed that a reduced "Core Parameter Set" of six indices (including EDA, Arias Intensity, and Vmax/Amax explains 89% of the variance, offering a practical subset for ground motion selection. Finally, manifold learning techniques (t-SNE and UMAP) demonstrated that the complex seismic damage landscape can be unfolded into a quasi-linear manifold, validating the stability of the proposed clustering.

Key Words
clustering analysis; machine learning; principal component analysis (PCA); seismic damage prediction; t-distributed stochastic neighbor embedding (t-SNE); uniform manifold approximation and projection (UMAP)

Address
Hayri Baytan Ozmen: Department of Civil Engineering, Usak University, Usak 64200, Türkiye
Esra Ozer: Department of Civil Engineering, Tokat Gaziosmanpasa University, Tokat 60250, Türkiye

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