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

sem
 
CONTENTS
Volume 94, Number 2, April25 2025
 

Abstract
Fabric-reinforced cementitious matrix (FRCM) is used to strengthen the structural performance of deteriorated reinforced concrete members. Unlike fiber-reinforced polymer (FRP) strengthening, the fabrics are embedded inside the cement matrix to prevent performance degradation owing to exposure to high temperatures and ultraviolet radiation. In exterior strengthening methods, the integrity of the strengthening material and concrete substrates plays an important role in determining the strengthening performance. This study aimed to evaluate the strength of FRCM-strengthened flexural members by considering the bond mechanism that reflects the failure mode of FRCM between the cement matrix and fabrics. In particular, the previously proposed FRCM bond behavior evaluation model was applied to flexural specimens based on the relationship between the maximum bond strength and effective bond length, and the flexural strength of specimens strengthened by FRCM from the existing literature was evaluated. As evaluated by a bond behavior model that takes into account the number of fabrics, spacing between fabrics, and the effect of the direct stress transfer between the cement matrix filled in the grid of fabrics, the mean, standard deviation, and coefficient of variation of the experimental results for the calculated results were 1.216, 0.185, and 0.152, respectively.

Key Words
bond mechanism; fabric-reinforced cementitious matrix; flexural strength; sectional analysis; strengthening method

Address
Yujae Seo: Architecture Convergence Laboratory of Industry-Academic Cooperation Foundation, Hankyong National University, Jungang-ro 327, Anseong, Gyeonggi 17579, Republic of Korea
Hyunjin Ju: School of Architecture and Architectural Engineering, Hankyong National University, Jungang-ro 327, Anseong, Gyeonggi 17579, Republic of Korea
Deuckhang Lee: Department of Architectural Engineering, Chungbuk National University, Chungdae-ro, Cheongju, Chungbuk 28644, Republic of Korea

Abstract
This paper presents an experimental and numerical study of the structural performance of normal strength concrete (NSC) filled in ultra-high performance concrete (UHPC) tube circular columns (UHPC-NSC columns) under axial compression. The steel fibers volume fractions of UHPC and the loading methods were exprimentally investigated as main parameters. The thickness and compressive strength of UHPC tubes were subsequently evaluated using a modeling approach. Three volumes of steel fibers including 0%, 1% and 2% were adopted for UHPC mixture. Six short UHPC-NSC circular columns were tested under loading on the entire section and on only NSC core. One control circular short columns made of NSC was also tested under axial compression. The experimental results indicated that as compared to the control columns, the utimate loads of the UHPC-NSC columns are significantly increased. When volume of steel fibers increases, the ultimate load and ductility of UHPC-NSC columns increases. For UHPC-NSC columns under loading on only the NSC core, the ultimate loads of UHPCNSC columns with UHPC having fiber volume of 0%, 1% and 2% were 20.12%, 29.22% and 41.73% higher than that of the control column, respectively. For UHPC-NSC columns loaded on the entire section, the ultimate loads of UHPC-NSC columns using UHPC having fiber volume of 0%, 1% and 2% were 178.23%, 181.31% and 246.76% higher than that of the control column, respectively. The UHPC-NSC columns loaded on the entire section had ultimate load higher than those loaded on NSC core, but their ductility was lower. Finally, a finite element model (FEM) was developed to verify the test results with a good agreement. Based on the established FEM, a parametric study on the effect of the thickness and compressive strength of UHPC tube on the structural performance of UHPC-NSC columns was conducted. Deriving from the findings in this paper, UHPC can be considered as a potential material to produce thin walled tubes and to work as formworks for filling NSC.

Key Words
composite columns; FEM; NSC; steel fibers; UHPC

Address
An H. Le: NTT Hi-Tech Institute, Nguyen Tat Thanh University, Ho Chi Minh City, Vietnam
Thang A. Le: Faculty of Civil Engineering, University of Technology and Education, Ho Chi Minh City, Vietnam

Abstract
The concrete filled steel tubular (CFST) truss girder consists of a CFST truss and a concrete deck. The failure mechanism and flexural strength of the girder were observed to be different under various failure modes, especially for continuous girder. To promote the engineering application of this innovative type of girder bridge, a fast strength prediction method with high accuracy was proposed which can be used in preliminary design stage. The method was developed based on pin-jointed analysis and the efficient factors of truss members were defined. The failure modes prediction and flexural strength calculation can be achieved by comparing the efficient factors of different members. The prediction results of simplified method were verified by the finite element analysis. The method can take the joint resistance into consideration and greatly simplify the design process of the CFST girder bridges. The design recommendations of the CFST truss girder were proposed based on the simplified method.

Key Words
concrete filled steel tube; continuous truss girder; failure mode; flexural strength; simplified calculating method

Address
Yinping Ma, Yongjian Liu, Zehong Yang, Wei Zhao, Jingli Chen: School of Civil Engineering, Chongqing University, Chongqing, 400045, China
Hongjie Chen, Jiang Liu: School of Highway, Chang'an University, Xi'an, 710064, China

Abstract
In this study, the effects of drum height on masonry dome behavior were examined experimentally and numerically by taking into account the domes with and without windows. Within the scope of the study, a total of eight domes, two of which were references (without drums) and six with different drum heights, were tested. One of the references was produced without windows and the other with windows. With window dome test elements having a drum height of 300 mm and 400 mm and windowless dome test elements with a drum height in the range of 100 mm, 200 mm, 300 mm, and 400 mm were examined. Numerical modeling of experimentally tested dome elements using the LUSAS analysis program was also examined and the experimental results were compared with the numerical results. As a result of the study, it was observed that the height of the drum significantly affected the load carrying capacity and horizontal displacement of the domes. It was determined that the lowest height drum application increased the load-carrying capacity of the dome by about 30% according to the drum-free reference test element. As the drum height increased, the load-carrying capacity and rigidity of the dome increased significantly, and the horizontal displacements decreased.

Key Words
dome drum; drucker-prager criterion; drum height; lusas software; masonry dome

Address
Fatih K. Firat and Sukran Tanriverdi: Department of Civil Engineering, Engineering Faculty, Aksaray University, 68100, Aksaray, Turkey

Abstract
The paper presents a two-dimensional exact elasticity solution of a functionally graded material beam with rectangular cross section. The exact solution is based on displacement-based approach under plane stress condition. The beam is subjected to different types of transverse loads, such as uniformly distributed, concentrated, and partial uniform loads. The elastic modulus of the FGM beam varies across its thickness direction according to the exponential law of distribution. Since exact solutions are not available for loading cases other than sinusoidal load, the exact solutions for FG rectangular beam subjected to uniformly distributed load, concentrated load and partial uniform load are obtained and presented for the first time. The influence of aspect ratio and the inhomogeneity of FGM is examined using the present exact solution. The result presented in this study can be served as benchmark solutions to verify the validity of 2D approximate beam theories.

Key Words
concentrated load; elasticity solution; exponential law; functionally graded material beam; gradation factor

Address
Manasi S. Raundal, Sharvari N. Dhepe, Abhay N. Bambole and Yuwaraj M. Ghugal: Department of Structural Engineering, Veermata Jijabai Technological Institute, Matunga, Mumbai, 400019, Maharashtra, India

Abstract
Improving the durability of reinforced concrete has become a concern due to the high maintenance cost and safety aspects. In specific, the failure due to shear loading can be catastrophic and requires modifications in the micro-structure of concrete with improved ductility characteristics. Though engineered cementitious composites (ECC) are emerging as a substitute for traditional concrete, their high cost (3 times) limits their practical applicability. This study attempts to compare the effectiveness of the novel and sustainable bio-fiber-reinforced ECC beams when compared with the readily accessible artificial fiber-based ECC members. The proposed research compares the efficiency of using bio-fibers for instance kenaf, pineapple, flax and hemp to standard ECC made of PVA, polypropylene (PP), or a hybrid of PVA and PP. The test sequence contains testing of sixteen ECC beams with 2.0% discrete natural or artificial fibers as specified above. In addition to the full-scale tests, a nonlinear finite element analysis was carried out by using the commercially available software ABAQUS and validated with benchmark experiments. Test outcomes showed that the use of natural fibers was very effective in increasing the ultimate shear resistance by a perfect crack-bridging mechanism on par with the artificial fiber-based ECC sections. Specifically, the inclusion of flax fibers attained the highest shear load of 56.2 kN with a corresponding energy absorption capacity of 477.5 Joules. Furthermore, the finite element analysis predicted peak shear capacity that matched the experimental results.

Key Words
AIJ method; bio-fibers; ECC; hybrid fibers; shear capacity natural fibers; shear loading

Address
M. Chellapandian, U. Brindha: Department of Civil Engineering, Mepco Schlenk Engineering College, Sivakasi, 626005, India
J. Maheswaran: St. Xavier's Catholic College of Engineering, Chunkankadai, Nagercoil, 629003, India
N. Prem Kumar: Structural Engineering Division, IIT Hyderabad, Kandi, Sangareddy, 502285, India

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