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CONTENTS
Volume 57, Number 4, November 25 2025
 

Abstract
The paper is devoted to a hybrid three-dimensional (3-D) mathematical modeling to study transient dynamic response of porous functionally graded (FG) truncated conical shells subjected to an asymmetric shock pressure. The hybrid solution method is based on layerwise theory, differential quadrature method (DQM), and Fourier series expansion. Firstly, a Fourier series expansion is used for the displacement components and dynamic pressure in the circumferential direction. Then the layerwise theory is employed to approximate the displacement components in the radial direction. Finally, the DQM is applied to discretize the governing equations in both spatial and time domains. Five cases of different porous distribution along the thickness of the functionally graded shell are considered and the results are compared to the similar non-porous FG shell. The results reveal that the porosity distributions have significant effect on the magnitude of stress components created on the surfaces.

Key Words
asymmetric shock pressure; differential quadrature method; layerwise theory; porous functionally graded materials; transient dynamic response; truncated conical shells

Address
Ehsan Selahi: Department of Mechanical Engineering, Marv. C., Islamic Azad University, Marvdasht, Iran

Abstract
The use of pultruded fibre-reinforced polymer (FRP) profiles as structural elements in building and construction has been facilitated by the development of pulwinding technology. Nevertheless, a lack of understanding and associated design guidelines for profiles subjected to cyclic loads are limiting their application to structures subject to repetitive loading and seismic events. This paper reports a numerical investigation using finite element (FE) modelling on the cyclic bending behaviour of box pulwound FRP (PFRP) profiles. The FE model, which is validated with experimental data, investigates the influence of key cross-sectional geometric parameters, namely the flange thickness (tf), web thickness (tw), corner radii ratio (r/R), and cross sectional aspect ratio (h/b). It also concludes three optimised design configurations for applications of serviceability, strength, and energy absorption. The effect of these design parameters on the failure mode, moment capacity, secant stiffness, and energy absorption capacity was quantified and the related interactions were determined by a full-factorial experimental matrix. The tf, r/R, and h/b controlled the design of the profile for energy absorption, bending moment, and secant stiffness by 42.2%, 47.6%, and 49.3%, respectively. Considering the related interactions in the design will maximise the bending strength, secant stiffness, and energy absorption capacity up to 1.66, 1.42, and 1.50 with an increase in the material cost of only up to 10.2%, 7.9%, and 16.8%, respectively, compared to the control profile.

Key Words
box pultruded GFRP beam; corner radius; cross-sectional geometry optimisation; cyclic loading; finite element analysis

Address
Mohammad Alhawamdeh:Department of Civil Engineering, Tafila Technical University, Tafila 66110, Jordan

T. Tafsirojjaman:School of Architecture and Civil Engineering, The University of Adelaide, Adelaide 5005, Australia

Yue Liu:Research Institute of Urbanization and Urban Safety, School of Future Cities, University of Science and Technology Beijing, Beijing 100083, China

Allan Manalo:University of Southern Queensland, Centre for Future Materials, Toowoomba, QLD 4350, Australia

Abstract
This paper presents an experimental and numerical study on the flexural behavior of a new composite beam system. The system is composed of I-shaped steel beams, partially encased in reinforced concrete and filled with rock wool insulation. The experimental investigation included three large-scale composite steel-concrete beams and one steel beam as a reference. Key variables such as the thickness of the concrete layer and concrete strength were examined. The study focused on analyzing failure modes, load-deflection curves, and the strain distribution in both the concrete and steel sections. The experimental results indicate that the composite beam system significantly outperformed the reference steel beam. Notably, the proposed composite beams demonstrated an initial stiffness that was about 70% higher, a yield strength improvement of approximately 61%, and an ultimate load capacity increase of around 65%. These enhancements highlight the effectiveness of the composite design in enhancing structural performance. The composite beams also exhibited a ductility ratio exceeding 5 and confirmed linear strain distribution along the beam height, validating the plane section assumption. Additionally, a numerical model was developed and validated using the experimental results, which highlighted that design factors such as steel strength and section dimensions are more critical than concrete strength in optimizing the composite beam system.

Key Words
bearing capacity; composite beam; flexural behavior; numerical modeling; steel-concrete composite

Address
Amr M. A. Moussa:1)School of Civil Engineering, Southeast University, Nanjing 211189, China
2)Civil Engineering Department, Faculty of Engineering, South Valley University, Qena 83523, Egypt

Hamdi S. N. Alzabli:School of Civil Engineering, Chang'an University, Xi

Abstract
Slender plate girders are frequently employed in the construction of steel bridges due to their resistance to bending and light weight in comparison to reinforced concrete beams. In some cases, the webs of these girders are horizontally curved in order to overcome limitations presented during the installation. This paper aims at investigating the elastic buckling capacity of horizontally curved, longitudinally stiffened, steel plate girders subjected to patch loading. A linear buckling analysis is performed using the finite element method. Thereafter, a parametric analysis is conducted to investigate the effect of the girder curvature, the position and size of the stiffener, and the loading length. The results show that the buckling coefficients increase with both the girder curvature and size of the stiffener. In the end, an expression for the patch loading buckling coefficient is obtained through symbolic regression. Ultimately, two analytical expressions for the patch loading buckling coefficient (kF) are proposed: one for unstiffened girders, and another for stiffened girders, both derived through symbolic regression. The comprehensive results highlight the effectiveness of machine learning (ML) approaches in predicting buckling coefficients.

Key Words
horizontally curved girder; linear buckling analysis; linear finite element analysis; longitudinal stiffening; machine learning; patch loading

Address
Carlos Graciano:Universidad Nacional de Colombia, Facultad de Minas, Departamento de Ingeniería Civil, Calle 59A No 63-20, Medellín 050034, Colombia

Rolando Chacón:Universitat Politècnica de Catalunya, Departamento de Ingeniería Civil y Ambiental, Calle Jordi Girona, 1-3. 08034, Barcelona, España

Euro Casanova:Universidad del Bío-Bío, Departamento Ingeniería Civil y Ambiental, Avenida Collao 1202, Código Postal 4051381, Concepción, Chile

Ahmet E. Kurtoglu:Iğdlr University, Department of Civil Engineering, Şehit Bülent Yurtseven Kampüsü, 76000, Iğdlr, Türkiye

Nelson Loaiza:Universidad de Medellín, Facultad de Ingeniería, Departamento de Ingeniería Civil, Cra 87 # 30-65 Belén los Alpes, Medellín, Colombia

Abstract
Buckling restrained braces (BRBs) have gained significant prominence as modern energy-dissipating elements, particularly in seismic-prone areas. Tubular cores have typically been preferred over rectangular ones due to their superior in plane and out-of-plane performance. This study introduces an all-steel BRB with an integrated pre-tensioning system to strengthen its out-of-plane stability. A verification study was conducted on two research papers to assess element representation and compare the outcomes, revealing a high degree of consistency between the experimental results and the numerical results. In this study, two pre-tensioning configurations (single and double) were accurately analyzed using 3D Finite Element Analysis (FEA). Additionally, the study explored the influence of different steel grades (St. 37, 44, and 52) and initial pre-tensioning force levels. The research consisted of three phases. The initial phase involved validating prior experimental studies on traditional and pre-tensioned BRBs. The second phase focused on designing the BRB models under examination. In the final phase, the study assessed how various parameters affected the behavior of the proposed BRB under cyclic loading conditions. The results showed that implementing the proposed pre-tensioning system significantly reduced the external restraining plate, by approximately 58% for the single pre-tensioning system and 67% for the double pre-tensioning system. Moreover, higher-grade steel materials increased compressive capacity while maintaining consistent axial displacement. An initial pre-tensioning force of 100 kN emerged as the optimal value for the analyzed models.

Key Words
all-steel BRBs; finite element analysis; hysteretic behavior; out-of-plane instability; pre-tensioning systems

Address
Mohamed Emara:Structural Engineering Dept., Faculty of Engineering, Zagazig University, Zagazig, 44519, Egypt

Muhammad E. Kamel:Structural Engineering Dept., Faculty of Engineering, Zagazig University, Zagazig, 44519, Egypt

Eman Elshamy:1)Structural Engineering Dept., Faculty of Engineering, Zagazig University, Zagazig, 44519, Egypt
2)Dean of obour high institute of engineering and technology, Egypt

Mohamed Selim:Structural Engineering Dept., Faculty of Engineering, Zagazig University, Zagazig, 44519, Egypt

Abstract
Based on high-cycle fatigue tests and microstructural analysis, the fatigue performance and fracture failure mechanisms of butt joints in welded tubular structures were investigated. According to static behavior of the butt joints, high cycle fatigue experiments were carried out at different stress levels. A life prediction model for butt joints of welded tubular structures under high-cycle fatigue load was proposed by introducing Morrow stress-life fatigue curve. With fracture micro morphology analysis, the fracture failure mechanism of butt joints in welded tubular structures was revealed. The experiment results indicate that the welded tubular structure exhibited brittle damage at the weld seam under fatigue loading. The test was cycled 2 million times under the stress ratio R = 0.1, and the fatigue strength was 156.29MPa. The resulting fatigue life prediction formula demonstrated good agreement with the experimental results. Based on the fatigue experimental results, the fatigue life prediction model applied to high-cycle fatigue was established. With a large number of fatigue striations in the crack propagation zone, the fatigue fracture was smooth and neat at the crack source, while the final fracture zone occupied a small proportion of the fracture plane.

Key Words
butt joints; fatigue life; high-cycle fatigue testing; partial strain fatigue analysis; welded tubular structures

Address
Yanlin Guan:Dept. of Civil Engineering, School of Architecture and Civil Engineering,
Jiangsu University of Science and Technology, Zhenjiang, 212100, China

Yaqiang Yang:Dept. of Civil Engineering, School of Architecture and Civil Engineering,
Jiangsu University of Science and Technology, Zhenjiang, 212100, China

Wenping Du:Dept. of Civil Engineering, School of Architecture and Civil Engineering,
Jiangsu University of Science and Technology, Zhenjiang, 212100, China

Mohamed F.M. Fahmy:Dept. of Civil Engineering, Faculty of Engineering, Assiut University, Assiut, 71516, Egypt

Haitao Wang:Dept. of Civil Engineering, College of Civil and Transportation Engineering, Hohai University, Nanjing,210098, China

Jing Cui:Dept. of Civil Engineering, College of Civil Engineering and Architecture, Henan University of Technology, Zhengzhou, 450001, China

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