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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 307 Abstracts search results
Document:
24-044
Date:
March 24, 2025
Author(s):
Hong Chen, Meng-Di Jia, Rena C. Yu, Jian-Jun Zheng, and Zhi-Min Wu
Publication:
Materials Journal
DOI:
10.14359/51746713
23-293
March 1, 2025
T. Asheghi Mehmandari, M. Shokouhian, M. Imani, K. F. Tee, and A. Fahimifar
Volume:
122
Issue:
2
Abstract:
This study investigates the behavior of recycled steel fibers (RSFs) recovered from waste tires and industrial hooked-end steel fibers (ISF) in two single and hybrid reinforcement types with different volume content, incorporating microstructural and macrostructural analyses. Scanning electron microscopy (SEM) is used to study the microstructure and fractures, focusing on crack initiation in the fiber interface transition zone (FITZ). The macrostructural analysis involves using digital image correlation (DIC) software, Ncorr, to analyze the split tensile behavior of plain and fiber reinforced concrete (FRC) specimens, calculating strain distribution and investigating crack initiation and propagation. The SEM study reveals that, due to the presence of hooked ends, industrial fibers promoted improved mechanical interlocking; created anchors within the matrix; added frictional resistance during crack propagation; significantly improved load transfer; and had better bonding, crack bridging, and crack deflection than recycled fibers. RSFs significantly delay crack initiation and enhance strength in the pre-peak zone. The study suggests hybridizing recycled fibers from automobile tires with industrial fibers as an optimum strategy for improving tensile performance and using environmentally friendly materials in FRC.
10.14359/51744375
23-281
Carlos A. Arteta, Jefferson Piedrahita, and Christopher L. Segura Jr.
Structural Journal
The adequate seismic behavior of slender reinforced concrete (RC) structural walls relies heavily on the effectiveness of the boundary element (BE) in providing stable resistance against combined axial and flexural-shear compression demands resulting from gravity loading and lateral earthquake deformations. The geometric properties of the BE, including thickness and confined length, as well as the arrangement, detailing, and quantity of transverse reinforcement, play crucial roles in achieving a stable compressive response. Laboratory tests on isolated BE specimens subjected to uniform axial compression or cyclic axial tension and compression have been instrumental in understanding the influence of these variables on the compressive behavior of wall BEs. This study uses a database of experimental results from 45 rectangular BE specimens to establish empirical relationships between compressive force and strain, accounting for geometric and transverse reinforcement design parameters. A novel auto-regularizing model is proposed to estimate the compressive behavior within the damaged zone of a BE, based on its geometry and transverse reinforcement.
10.14359/51743302
23-237
Vitalii Mitrofanov and Pavel Mytrofanov
The limitations of known fracture mechanics (FM) models are noted, and to overcome them, a specific FM model was proposed based on modeling the stress distribution only along the crack fracture process zone (FPZ), with elastic concrete behavior out of the FPZ. This peculiar stress distribution was called physically verisimilar stress (PVS), and it was accepted as the basis of the proposed PVS model, which used three material parameters: maximum stress, intrastructural linear size a, and dimensionless value n, taking into account the plastic properties of the material. The relationships for determining the PVS model parameters were suggested for concrete. Strength problems were solved by the modified method of sections, in which the PVS was applied along the FPZ. The FM model based on PVS and the modified method of sections led to an acceptable in-practice method of strength design, which was considerably simpler than the known phase-field method. The proposed PVS model and design method allow for the prediction of the cracks development, considering their stable growth up to the critical (ultimate) values of the crack length and load. The unstable cracks propagation is considered also. The paper provides examples of designs and shows sufficient theoretical strength relative to the experimental one.
10.14359/51743293
22-359
December 1, 2024
S. H. Chu, L. Sneed, D.-Y. Yoo, and A. K. H. Kwan
121
6
End hooks of steel fibers provide a stronger bridging force across the concrete matrix in steel fiber-reinforced concrete (SFRC). In this work, SFRC beams were prepared with steel fibers of the same length and diameter but different types of end hooks (straight, three-dimensional [3D], four-dimensional [4D], and fivedimensional [5D]) at increasing fiber volumes (0.0, 0.5, 1.0, 1.5, and 2.0%). Four-point bending tests conducted on each SFRC beam yielded load-deflection curves, from which the first cracking strength, flexural strength, and fracture toughness up to certain deflection-to-beam length ratios were obtained. The test results showed that the presence of end hooks remarkably enhanced the flexural strength and toughness of the SFRC beams, and this enhancement was amplified with an increasing number of hooks. Quantitative analysis revealed the hooking index, a factor introduced herein to delineate the efficiency of various types of hooks, was 1.00, 1.30, 1.60, and 2.10, respectively, for straight, 3D, 4D, and 5D steel fibers used in the present study. Lastly, empirical models for predicting flexural strength and toughness were established with high prediction accuracy.
10.14359/51743281
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