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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 7 Abstracts search results
Document:
23-308
Date:
March 1, 2025
Author(s):
Reza Sarkhosh and Joost Walraven
Publication:
Structural Journal
Volume:
122
Issue:
2
Abstract:
Subjected to either tensile or compressive loads, concrete is susceptible to the effect of sustained loading. To address this, common practice in building guidelines typically involves applying a sustained loading factor ranging from 0.6 to 0.85. Given that the shear capacity of structural members without shear reinforcement is linked to the concrete strength, one might question whether there is a comparable sustained loading impact on shear. To address this inquiry, a total of 18 reinforced concrete beams without shear reinforcement were subjected to prolonged sustained loading, with a load intensity factor (ratio of applied sustained shear load to short-term shear resistance) ranging from 0.88 to 0.98. Several beams endured the sustained loading test for an extended period, close to a decade, before the test was terminated. Interestingly, in contrast to concrete subjected to direct compression or tension, it was observed that sustained loading did not affect the shear capacity. Some early results of this experimental study, where concrete beams were subjected to up to 4 years of sustained loading, have been previously published by Sarkhosh and Sarkhosh et al. This paper concludes the results of the testing campaign of up to a decade of sustained loading, with additional results and findings.
DOI:
10.14359/51743303
20-308
November 1, 2022
Sina Hassanpour, Alireza Khaloo, Mojtaba Aliasghar-Mamaghani, and Hooman Khaloo
119
6
This research studies the effect of glass fiber-reinforced polymer (GFRP) bars as compressive reinforcement in reinforced concrete (RC) beam members. Three singly and six doubly reinforced GFRP-RC beams were tested under a four-point loading configuration. The effect of compressive reinforcement on the load-bearing capacity, ductility, stiffness, and failure mode is determined. Also, the compressive performance of GFRP bars is evaluated by testing GFRP-RC cylinders. According to the results, GFRP bars in compression had a limited contribution to enhancing flexural strength, and the maximum increment in the flexural capacity of doubly reinforced beams compared to singly reinforced specimens was 5%. GFRP-RC cylinders demonstrated a similar pattern, as the maximum strength increase compared to control specimens was 8%. Based on the evaluation of GFRP behavior, the contribution of bars in compression is limited due to the maximum strain that concrete withstands under compression. Considering the singly reinforced specimens, due to the presence of compressive GFRP bars, the stiffness of the doubly reinforced beams was reduced (up to 16%); however, the curvature and ductility were increased (up to 10% and 35%, respectively). In the end, a method based on deformations at the near-peak and peak load capacity was proposed to calculate the ductility of beams. The method predicts ductility enhancement due to compressive bars, as was observed in experiments, and also makes a distinction on failure modes.
10.14359/51734792
13-044
September 1, 2014
Abdoladel Shoaib, Adam S. Lubell, and Vivek S. Bindiganavile
111
5
At the member scale, very few previous tests reported for shear-critical steel fiber-reinforced concrete (SFRC) members have examined specimens with depths greater than 300 mm (11.8 in.), preventing a detailed assessment of the so-called size effect in shear for SFRC. This paper reports on laboratory results of 12 SFRC specimens with an overall height from 308 to 1000 mm (12.1 to 39.4 in.), and a constant shear span-effective depth ratio of 3. Specimens contained normal or high-strength SFRC with 1% volume fraction of hooked-end steel fibers and different longitudinal reinforcement ratios, but no stirrups. The test results show that the steel fibers increase the shear capacity relative to geometrically similar reinforced plain concrete members. The normalized shear stress at failure, however, was observed to decrease as the member depth increased, indicating that a size effect in shear occurs in SFRC members without stirrups. Modifications to the ACI 318-11 provisions for shear in SFRC members are proposed.
10.14359/51686813
D106-S02
March 1, 2009
Abdelsamie Elmenshawi, N. Subramanian, and Andor Windisch
106
Disc. 105-S28/From the May-June 2008 ACI Structural Journal, p. 290. Plastic Hinge Length of Reinforced Concrete Columns. )Paper by Sungjin Bae and Oguzhan Bayrak). Discussion by N. Subramanian. Disc. 105-S28/From the May-June 2008 ACI Structural Journal, p. 290. Plastic Hinge Length of Reinforced Concrete Columns. (Paper by Sungjin Bae and Oguzhan Bayrak). Discussion by Abdelsamie Elmenshawi. Disc. 105-S29/From the May-June 2008 ACI Structural Journal, p. 301. Control of Flexural Cracking in Reinforced Concrete. (Paper by R. Ian Gilbert). Discussion by Andor Windisch. Disc. 105-S30/From the May-June 2008 ACI Structural Journal, p. 308. Shear Strength of Thin-Webbed Post-Tensioned Beams. (Paper by Miguel Fernandez Ruiz and Aurelio Muttoni). Discussion by Andor Windisch.
10.14359/56365
JL69-01
January 1, 1972
ACI Committee 308
Journal Proceedings
69
1
Curing is defined as the process of maintaining a satisfactory moisture content and a favorable temperature in concrete during hydration of the cementitious materials so that desired properties of the concrete are developed. Two systems of providing the required moisture are explained in detail: (I) main-taining a moist environment by application of water; and (2) prevention of IOSS of mixing water by use of sealing materials. Basic principles of successful curing are outlined, and commonly accepted methods, procedures, and materials are described. Recommendations are given for curing pavements and other slabs on ground; for structures and buildings: and for mass concrete. For each of these categories, methods, materials, time and temperature of curing are recommended. Brief sections comment on curing requirements for precast products, shotcrete, preplaced aggregate concrete, refractory concrete, plaster and other applications.
10.14359/11244
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