Techno Press
Tp_Editing System.E (TES.E)
Login Search
You logged in as

acc
 
CONTENTS
Volume 18, Number 3, September 2024
 

Abstract
This research investigates the influence of defects, such as porosities, that may arise during the manufacturing process of functionally graded material (FGM) plates. These defects have the potential to significantly impact the behavior of structural elements. The primary focus of the study is the examination of the free vibration characteristics of porous and cracked FGM plates for different material composition types. The distribution of Young's modulus along the thickness of the plate is modeled using a power-law formulation, while the Poisson's ratio remains constant. Various material gradation types are explored, and the proposed model's accuracy is assessed through comparative analysis. Furthermore, the research investigates into how alterations in the porosity distribution rate, material gradation types, power-law index, thickness ratio, depth and location of the crack influence the fundamental frequency of the plates. It was found that the porosity with its various shapes, as well as the boundary conditions, significantly influence the dynamic behavior of an imperfect plate.

Key Words
crack; free vibration; functionally graded materials; Hamilton's principle; imperfect plate; porosity distribution rate

Address
(1) Draouche Khayra, Lazreg Hadji:
Laboratory of Geomatics and Sustainable Development, Ibn Khaldoun University of Tiaret, Algeria;
(2) Mohamed Ait Amar Meziane, Lazreg Hadji:
Department of Civil Engineering, University of Tiaret, Algeria;
(3) Lazreg Hadji:
Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City 70000, Vietnam;
(4) Hassen Ait Atmane, Riadh Bennai:
Laboratory of Structures, Geotechnics and Risks, Department of Civil Engineering, Faculty of Civil Engineering and Architecture, University Hassiba Benbouali of Chlef, Algeria;
(5) Royal Madan:
Department of Mechanical Engineering, Graphic Era (Deemed to be University), Dehradun 248002, Uttarakhand, India.

Abstract
The primary objective of the current study was to examine the strength and durability properties of a blend of geopolymer concrete (GPC) that included fly ash, lime, and slag cured at room temperature. For all mixtures, M25 grade concrete was used, which was designed in compliance with IS 10262-2019. Thirteen distinct concrete mix proportions were created, all with recycled coarse aggregate replacing 30%, 50%, and 100% of the NCA while keeping the alkalinity ratio and NaOH molarity unchanged. The concrete properties viz: workability, compressive strength, split tensile strength, ultrasonic pulse velocity (UPV), water absorption, density, sulphate attack and sorptivity were studied. Compressive strength, split tensile strength were determined at the ages of 7, 28 and 28 days respectively. The test results have exhibited that with increase in recycled aggregate replacement the strength declined. The decline in the strength is due to weak interfacial transition zone between the paste and aggregate. From the experimental results, it may be concluded that the desired strength of GPC can be obtained from a blend of fly ash with GGBS as it gives better results on compared to the other mixes even when 100% NCA were replaced with 100% RCA. Furthermore, empirical correlations were established to forecast split tensile strength from compressive strength and compressive strength based on density and UPV.

Key Words
Geopolymer concrete (GPC); Natural Coarse Aggregate (NCA); Recycled Coarse Aggregate (RCA); sorptivity; Ultra-Sonic Pulse Velocity (UPV)

Address
Civil Engineering Department, SoS Engineering and Technology, GGV, Bilaspur (C.G.), India.

Abstract
In order to overcome the errors caused by the subjective and random factors in the evaluation of the quality of recycled coarse aggregate (RA), and to ensure that a scientific and reasonable choice is made for its application field. In this paper, seven parameters of apparent density, porosity, soundness, crushing index, content of fine powder, content of clay lump and water absorption rate were used as comprehensive evaluation indicator of the quality grade of RA. The quality grade of RA was divided into four grades of disqualified, qualified, good and high quality. Analysis hierarchy process-gray variable weight clustering method was used for evaluation. The evaluation was divided into three steps, including: 1) weight calculation of the seven parameters by the method of analysis hierarchy process (AHP); 2) hierarchical classification by the method of grey variable weight clustering (GC); and 3) establishment of a quality evaluation method for RA. Then the scientificity of the evaluation method was tested with examples. The calculation results show that the evaluation method can provide theoretical support for the research on the quality grade of RA and has certain guiding significance.

Key Words
analysis hierarchy process; comprehensive evaluation; grey variable weight clustering; quality grade; recycled coarse aggregate

Address
(1) Xiaohui Yan, Ting Liu, Bei Zhang:
Department of Municipal and Ecological Engineering, Shanghai Urban Construction Vocational College, Shanghai 200438, China;
(2) Dong Lu:
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong SAR 100872, China.

Abstract
In this present work, an analytical and numerical analysis was carried out to predict the flexural response of RC beams strengthened with Ultra-high-performance concrete (UHPC) jackets of varying thicknesses (5, 10 and 15 mm). The analytical models aimed to incorporate the geometric and material properties of the constituent components, such as Young's modulus, compressive strength and tensile strength of UHPC, Normal strength concrete (NSC), and steel. The momentcurvature and deformation behaviour of the composite RC beams was evaluated from the analytical model. Furthermore, the numerical analysis is performed using finite element tools to predict the same and compare it with the analytical model. The primary objective is to validate the developed analytical and numerical model with the results of the UHPC strip attached at the bottom of the beams available in the literature. The relative study of strengthened beams of varying thickness over control beams illustrated a significant increase in flexural response with an increase in the thickness of UHPC jacketing. The maximum increase in flexural capacity for UHPC jacketed beam (15 mm) is 45% compared to the reference beam. The deviation in results between the analytical and numerical models is less than 7.2% and closely match the existing experimental results. The outcome of this study provided essential insights into the effectiveness of UHPC jacketing as one of the strengthening solutions for damaged/distressed RC structures.

Key Words
analytical modelling; Finite Element Analysis; reinforced concrete beam; strengthening; ultra-highperformance concrete jacketing

Address
(1) K. Manikaandan, P. Ganesh:
School of Civil Engineering, SASTRA Deemed to Be University, Thanjavur, 613401, India;
(2) A. Ramachandra Murthy:
Cheif Scientist, CSIR- Structural Engineering Research Centre, Chennai 600113, India.

Abstract
This study involves the experimental investigation of the effects of steel fiber volume fraction and aspect ratio on the fracture parameters of steel fiber reinforced lightweight concrete (SFLWC). Specimens were produced by adding steel fibers with aspect ratios (steel fiber length/steel fiber diameter) of 55, 65 and 80 at fiber contents of 0, 15 kg/m3, 30 kg/m3, 45 kg/m3 and 60 kg/m3 to lightweight concrete produced using pumice aggregate. The reference lightweight concrete strength class was taken as LC25/28. Compressive, splitting tensile and flexural tensile tests were performed on specimens. Load-crack mouth opening displacement (CMOD) curves, fracture energies, characteristic lengths and fracture toughness were also determined by flexural tests. The stresses transferred to the steel fibers after the first crack were carried by the steel fibers, preventing sudden failure and this behavior continued until the steel fibers were pulled out from the matrix. Accordingly, the steel fibers improved the behavior of the concrete after the peak load and continued to deform under decreasing load. With increasing amount of strain, the toughness or energy absorption capacity of the semi-brittle concrete increased. Based on the test results obtained, significant increases in fracture energy, splitting and flexural tensile strengths were obtained by increasing the amount of steel fiber.

Key Words
concrete fracture; concrete technology, construction materials, lightweight aggregate (LWA) concrete, steel fiber reinforced concrete (SFRC)

Address
Civil Engineering Department, Faculty of Architecture and Engineering, Yozgat Bozok University, Yozgat, Turkey.

Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2025 Techno-Press ALL RIGHTS RESERVED.
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Email: admin@techno-press.com