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CONTENTS
Volume 36, Number 4, October 2025
 

Abstract
The three-edge bearing test (TEBT) is a crucial means of conducting mechanical performance tests and assessing the mechanical properties of concrete pipelines. This study analyzes the failure process, load-bearing capacity, and circumferential strain of concrete pipelines while comparing the numerical simulation results of three constitutive models. The outcomes demonstrate that the strain curve trends within the tensile and compressive regions of concrete can be deduced by examining variations in the slope of the damage factor curve, and the numerical simulation results obtained from the constitutive model based on the equivalent energy method of uniaxial stress curve exhibit remarkable accuracy, it achieves a maximum deviation of 12.03% in compressive damage factors and 40.2% in tensile damage factors compared to other models. Moreover, the present research reveals that different loading beam or buffer rubber configurations during the loading process can result in distinct stress areas within the pipeline, where larger loading areas lead to an earlier critical bearing capacity for rapid crack propagation within the tensile zone of the pipeline. Quantitative analysis shows that line loads induce 18.7% higher peak stress at the pipe crown compared to area loads, but exhibit 37.2% faster stress attenuation from crown to waist (e.g., 82.83% residual strain under area load vs 67.45% under line load at waist position for 1.5 m-diameter pipes). Although the stress induced by area loads is 23.4% lower than that caused by line loads at the crown, its attenuation rate within the pipeline is 41.6% slower, particularly evident in smaller-diameter pipes where area load-induced stress maintains 74.3% of initial value at 1/2 pipe length versus 58.9% for line loads. Finally, an improved stirrup arrangement design is proposed to enhance the crack resistance of reinforced concrete drainage pipes while simultaneously reducing material costs, the improved stirrup arrangement reduces concrete strain by 37.14% in 1 m-diameter pipes while saving 50% of steel material, achieving optimal cost-performance balance for small-diameter pipelines.

Key Words
carrying capacity; circumferential strain; concrete pipe; failure process; numerical simulation

Address
Xiangrui Han, Wentao Wang, Yinghao Miao, Pengpeng Li and Huifang Liu: National Center for Materials Service Safety, University of Science and Technology Beijing, Beijing, China
Yajian Wang: School of Engineering and Technology, China University of Geosciences (Beijing), Beijing, China
Linbing Wang: School of Environmental, Civil, Agricultural and Mechanical Engineering, University of Georgia, Athens, Georgia

Abstract
This paper presents a novel approach, utilizing image analysis to accurately and efficiently assess the resistance of self-compacting concrete (SCC) to vertical segregation. Examining varying levels of fluidity across five unique formulations enhanced the investigation of SCC segregation. We obtained images of SCC samples using a multifunction scanner, which ensured uniformity and reproducibility, thereby establishing a credible foundation for the suggested testing methods. The segmentation process consists of two stages: initial manual segmentation using AutoCAD to establish a critical reference, followed by automated segmentation with ImageJ. This automated approach extracts essential quantitative data, such as paste area and aggregate distribution, while also identifying potential mix defects. Consequently, we presented the longitudinal profiles of aggregate and paste distribution, which allowed us to link formulation parameters to structural outcomes. The study also introduced the Segregation Resistance Indicator (SRI) to evaluate the degree of segregation, classifying the data into three distinct levels for effective comparison between samples. The results demonstrate a robust association with another prevalent segregation indicator, indicating the high reliability of the new methodology. This framework facilitates the establishment of objective criteria for the acceptance or rejection of specific mixtures, thus improving its applicability in various construction scenarios.

Key Words
automatic segmentation; ImageJ; Python software; segregation resistance indicator; self-compacting concrete; surface profile; vertical segregation

Address
Mostefa Lallam: 1) Department of Civil Engineering, Faculty of Sciences and Technology, University of Mascara, Mascara,29000, Algeria, 2) Laboratory Mechanics of Structures, University of Tahri Mohamed, Bechar 08000, Algeria
Yassine Senhadji, Nadjet Berrekheroukh and Ramdane Oulha: Department of Civil Engineering, Faculty of Sciences and Technology, University of Mascara, Mascara,29000, Algeria
Abdelhamid Mammeri: Laboratory Mechanics of Structures, University of Tahri Mohamed, Bechar 08000, Algeria
Abdelkader Djebli: Laboratory of Mechanics of Materials, Energy and Environment (L2M2E), University of Mustapha Stambouli, Mascara 29000, Algeria

Abstract
In the present paper, the finite element approach for thermo-mechanical vibration analysis of porous FGM beam under various thermal load variations is studied. Three types of thermal loading variations are typically considered when accounting on porosities in a beam, usually, uniform, linear and nonlinear temperature rises. The proposed finite element is formulated according to the HSDT kinematical models, coupled with the Hamilton's principle to define the governing equations of motion. This leads to formulate, one-dimensional finite element that includes shear and thermal stress for free vibration analysis. Based on the obtained natural frequencies, a conceptual analysis is conducted to show the effects of the power-law exponents, porosity distributions, porosity volume fractions, thermal load, and the beam slenderness on the fundamental frequencies of FGM beams, under different boundary conditions.

Key Words
axial-bending coupling; FGM beam; finite element method; free vibration; porosity; shear locking; temperature effect

Address
Hadj Youzera: Laboratoire d'Etude des Structures et de Mécanique des Matériaux, Département de Génie Civil, Faculté des Sciences et de la Technologie, Université Mustapha Stambouli B.P. 305, R.P. 29000 Mascara, Algérie
Sid Ahmed Meftah: Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Université Djillali Liabes, Sidi Bel Abbes, Algérie
Abdelouahed Tounsi: 1) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia, 2) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Mofareh Hassan Ghazwani and Ali Alnujaie: 1) Department of Mechanical Engineering, College of Engineering and Copmuter Sciences, Jazan University, P.O Box 45124, Jazan, Saudi Arabia, 2) Engineering and Technology Research Center, P.O. Box 114, Jazan 82817, Saudi Arabia

Abstract
This work investigates the buckling analysis of isotropic and sandwich beams under various boundary conditions based on a new refined trigonometric shear deformation theory. This theory includes indeterminate integral variables in which any shear correction factor is not used, even less than the conventional theory of first shear strain (FSDT). The governing equations and boundary conditions are obtained by applying the virtual displacements principle. Galerkin's approach is utilized for FG sandwich beams with three different boundary conditions to solve the buckling problem for different boundary conditions. A detailed numerical study is carried out to examine the influence of power-law index, span-to-depth ratio, side-to-thickness ratio, and boundary conditions on the buckling response of isotropic and FGM sandwich beams. A good agreement between the results obtained and the available solutions of existing shear deformation theories demonstrates the proposed theory's precision.

Key Words
buckling sandwich beams; functionally graded materials; new refined shear deformation theory; various boundary conditions

Address
Fouad Bourada and Kouider Halim Benrahou: Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria
Lemya Hanifi Hachemi Amar: Ecole Nationale Supérieure d'Ingénieurs de Bretagne Sud, Institut de Recherche Dupuy de Lôme (IRDL), UMR CNRS 6027, Centre de Recherche, Rue de Saint Maudé-BP 92116, 56321 Lorient Cedex, France
Abdelhakim Kaci: 1) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria, 2) Université Dr Tahar Moulay, Faculté de Technologie, Département de Génie Civil et Hydraulique, BP 138 Cité En-Nasr 20000 Saida, Algérie
Abdelmoumen Anis Bousahla: Laboratoire de Modélisation et Simulation Multi-échelle, Université de Sidi Bel Abbés, Algeria
Mofareh Hassan Ghazwani: Department of Mechanical Engineering, Faculty of Engineering, Jazan University, P.O Box 45124, Jazan, Kingdom of Saudia Arabia
Abdelouahed Tounsi: 1) Material and Hydrology Laboratory, University of Sidi Bel Abbes, Faculty of Technology, Civil Engineering Department, Algeria, 2) Department of Civil and Environmental Engineering, King Fahd University of Petroleum & Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia
Hind Albalawi: Department of Physics, College of Sciences, Princess Nourah bint Abdulrahman University (PNU), P.O. Box 84428, Riyadh 11671, Saudi Arabia

Abstract
This study explored the effects of recycled aggregates (RA) by modifying the shrinkage and chloride penetration resistance of concrete. RA was heated at constant temperatures of 300, 500, and 700 oC for 30 min. Further, the measured shrinkage and chloride penetration resistance of the recycled aggregate concrete (RAC) were also adversely affected by the incorporation of RA. The results indicated that replacing 50% of NA with RA reduced compressive strength by 28.5% at 28 days. Shrinkage values for 100% RA replacement increased by 65.7% at 28 days compared to the reference, while chloride ion penetration (electric flux) doubled. Moreover, when the heating temperature of RA was lower than 500 oC, the compressive strength of RAC increased with increasing temperature and decreased when the temperature exceeded 500 oC. The shrinkage value and chloride ion penetration resistance of the RAC exhibited similar phenomena. The addition of secondary cementitious materials contributed to the compressive strength, shrinkage, and chloride penetration resistance of RAC. Heating RA at 500 oC improved compressive strength by 12.3% compared to untreated RA, reduced porosity to 15.3%, and minimized shrinkage. Incorporating 20% fly ash (FA) and 10% granulated blast-furnace slag (GBFS) enhanced compressive strength by 9.6% and reduced chloride flux by 27% at 120 days. In addition, pore structure characteristics were investigated, and it was found that the pore structure of RAC also improved owing to the heating of RA.

Key Words
chloride penetration; heating modification; pore structure; recycled aggregates; shrinkage

Address
Department of Municipal and Ecological Engineering, Shanghai Urban Construction Vocational College, Shanghai 200438, China

Abstract
The amount of garbage from glass and concrete structures grew daily, polluting the environment. Reducing the amount of trash and managing waste effectively are essential elements of sustainable development. One essential element of effective disposal methods in civil engineering projects is the reuse and recycling of waste. Using used glass as a natural aggregate substitute in concrete could help address the growing issue of efficient glass waste management in developing nations. There has been a lot of research on producing environmentally friendly concrete from glass trash or recycled concrete aggregate, but most of it has focused on these two resource categories separately. The combination of glass trash with recycled concrete aggregates to create environmentally friendly concrete, particularly in case of high strength concrete, has never been done before; more research is needed to fill in the gaps and provide recommendations. In this study, the compressive and tensile properties of eco-high strength concrete (HSC) were experimentally investigated using glass waste and old concrete particles as a replacement for natural big/small aggregate. The second uses coarse recycled glass aggregate (BG) to replace a large natural coarse aggregate (CBA) at ratios of 0, 10, 20, and 40%, while the first uses small, recycled glass aggregate (SG) to replace fine sand (FS) at a variety of levels (0, 10, 25, 50, and 100%). The third employs recycled concrete aggregate (RA) in conjunction with BGs as a substitute for CBA, while the fourth uses RA alone at a variety of levels (0, 16, 40 and 80%). The findings demonstrated that the compressive and tensile strengths of HSC dropped when SGs took the place of fine sand (FSs), especially when the replacement level was 100%. Tensile values declined by 5.4, 8.2, and 25%, respectively, while compressive characteristics of HSC decreased by 24.8, 27.66, and 38.03% when BG was used in place of 10, 20, and 40% of CBA. If 16, 40, and 80% of CBAs were substituted with RAs mixes without the use of BG, the strength at compression of HSC decreased by 18.1, 27.58, and 33.37%, respectively, in contrast to the reference mix without RAs. This study contributes to sustainable construction practices within construction engineering, particularly in optimizing material selection and minimizing lifecycle costs through eco-efficient concrete design.

Key Words
compressive resistance; glass waste; material optimization; optimization; project cost efficiency; recycled aggregate; risk in concrete design; tensile strength

Address
Sabry Fayed and Mohamed Ghalla: Department of Civil Engineering, Faculty of Engineering, Kafrelsheikh University, Egypt
Jong Wan Hu: 1) Department of Civil and Environmental Engineering, Incheon National University, Incheon 22012, South Korea, 2) Incheon Disaster Prevention Research Center, Incheon National University, Incheon 22012, South Korea
Ehab A. Mlybari, Rabeea W. Bazuhair and Yahia Iskander: Department of Civil Engineering, College of Engineering and Architecture, Umm Al-Qura University, Makkah 24382, Saudi Arabia

Abstract
To understand the strengthening and toughening mechanism of special-shaped steel fiber concrete, a numerical simulation was conducted considering the morphology of steel fiber. Based on the plastic damage mechanics theory and the constitutive relationship of the interface bonding between steel fiber and concrete, a model of a single special-shaped steel fiber pulling out from concrete was established by using the finite element method. After that, the pullout force-slip curve, the local stress variation of the single fiber, and the nephogram of concrete damage evolution were obtained. There are two peaks in the pullout force-displacement curves of the end hooked steel fiber, one peak caused by the shape changing of the fiber, and another caused by the interface debonding between the fiber and the concrete. Compared with the straight fiber, the pullout force gain ratios of type I and type II fiber are 14.5% and 24.41%, respectively. However, the maximum mean stress in type I steel fiber is around 10% larger than in type II steel fiber. It is found that the concrete corresponding to the type II steel fiber is damaged more severely than concrete corresponding to the type I steel fiber, the maximum compression damage degree is approximately 10% greater. For getting a better strengthen and toughen performance of the fiber concrete, the matching of fiber and concrete is essential to maximize the effectiveness of both fiber and concrete. The method proposed in this paper provides a theoretical reference for optimal steel fiber reinforced concrete design.

Key Words
cohesive contact behavior; fiber reinforce concrete; interfacial bonding property; plastic damage model; special-shaped steel fiber

Address
Yuanyuan Gao: 1) Hebei Key Laboratory of Green Construction and Intelligent Maintenance for Civil Engineering, Yanshan University, Qinhuangdao, 066004, China, 2) Hebei Province Engineering Research Center for Harmless Synergistic Treatment and Recycling of Municipal Solid Waste, Yanshan University, Qinhuangdao, 066004, China
Nkosilathi Lovewell Hlupo, Zhi Liu and Hongtao Jiang: 3School of Civil Engineering and Mechanics, Yanshan University, Qinhuangdao, 066004, China
Quan Qian: Hebei High Performance Building Material Technology Innovation Center, Qinhuangdao Municipal Building Materials Group Co. Ltd., Qinhuangdao, 066000, China

Abstract
On the basis of an examination of the general characteristics in the structural behavior of 3-D RC frame structures, this paper introduces the possibility of adopting a 2-D frame structural analysis in the preliminary design stage at which the initial design sections are determined, even in the case of asymmetric 3-D RC frame structures. Upon consideration of the creep deformation of concrete and the construction sequence, which dominantly affect the structural responses of concrete structures, material nonlinear analyses of RC frame structures are performed with the use of a numerical approach based on the moment-curvature relation of an RC section, because it can deliver computational efficiency in 3-D RC frame structures composed of many beams and columns. Furthermore, a simplified numerical solution procedure that can reflect the change in the moment-curvature relations with the magnitude of the axial force and the biaxial bending moments is introduced and its exactness is verified through correlation studies between experimental data and numerical results. Typical asymmetric 3-D RC frame structures are considered with variation in the arrangement of asymmetric upper floors, and the structural responses are analyzed from the perspective of member forces to examine whether the member forces determined through a 2-D analysis can be used in the preliminary design of asymmetric 3-D RC frame structures. Finally, through a comparison of member forces in RC frame structures, it can be concluded that 2-D RC frame analyses only considering the construction sequence can be utilized in the preliminary design of 3-D RC frame structures with or without symmetry.

Key Words
3-D RC frame structures; asymmetric structures; moment-curvature relation; preliminary design; structural analysis

Address
Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea

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