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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 73 Abstracts search results
Document:
SP275-66
Date:
March 1, 2011
Author(s):
H. R. Hamilton, C. W. Dolan, J. E. Tanner, and E. P. Douglas
Publication:
Symposium Papers
Volume:
275
Abstract:
This paper presents a test methodology that can be used to evaluate the durability of bonded CFRP systems used to repair and strengthen concrete beams. The test specimen is a 100 x 100 x 350 mm (4 in. x 4 in. x 14 in.) beam, tested in three-point bending (flexure) on a 300 mm (12 in.) span length. Two conditioning protocols are proposed depending on the anticipated exposure. For unprotected service conditions specimens are submerged in 60C (140F) water for 60 days. For protected service conditions, the specimens are exposed to 100% relative humidity at 60C (140F) for 60 days. Although the test method will not give a direct service life prediction, the testing presented in this paper indicate that the procedures were capable of differentiating a wide range of responses of deterioration of CFRP systems subjected to the test procedures.
DOI:
10.14359/51682476
SP275-67
Vicki L. Brown, Andrew Dinh, and Giovanna Iacono
The behavior of seventeen RC beams strengthened with FRP laminates mechanically fastened to their tension soffits with concrete anchor bolts is presented. The beams were tested in four-point bending on a 7.5 foot (2286 mm) span. Bolt diameter and spacing and FRP strip length were varied. The beams exhibited increases in yield moment ranging from 12.5% to 46%, and increases in ultimate moment from 30% to 75%, while displacement ductility ratios were 75% of values from un-strengthened control beams. The number of fasteners in the shear span had a greater impact on ultimate strength than did FRP strip length. Terminating the FRP strips in regions of larger bending moment resulted in an unexpected change of failure mode from concrete compression to shear. Measured strains in the FRP were less than those calculated assuming fully bonded conditions.
10.14359/51682477
SP275-63
Jiawei Shi, Hong Zhu, Zhishen Wu, and Gang Wu
This paper presents an experimental investigation into the bond behavior between basalt FRP (BFRP) sheet and concrete substrate under coupled effects of freeze-thaw cycling and sustained load. Specially designed double-lap shear specimens were exposed to up to 200 freeze-thaw cycles with sustained load. After exposure, the specimens were tested to failure. Digital Image Correlation (DIC) test method was applied to capture the full-field strain in the study. Nonlinear constitutive law of FRP-concrete interface was determined based on full-field deformation and strain analysis. Test results show that freeze-thaw cycling leads to significant decreases in load carrying capacity, ultimate slip, shear strength and increases in effective stress transfer length of FRP-concrete interface. Additional damage is generated when the load condition is taken into account during freeze-thaw cycling test. Moreover, apparent changes in failure mode were found with the increasing number of freeze-thaw cycles.
10.14359/51682473
SP275-64
Jianwei Huang and Riyad Aboutaha
In current International Codes for FRP Reinforced Concrete, an environmental reduction factor is applied to the tensile strength of GFRP bar to account for its long-term durability. In this paper, the approaches for the durability design of GFRP bars are discussed and corresponding limitations are addressed, followed by presentation of a newly developed design approach, which incorporates the effects of relative humidity, exposure temperature, and design life. By using time extrapolation and time-temperature shift approaches, a new equation for design strength of GFRP bar under various exposure time and temperature was proposed. The effect of moisture, in the form of relative humidity, was incorporated into the new equation by investigating the relationship between the relative humidity and concrete pore water. On the basis of reported durability data for E-glass/VE GFRP bars embedded in moist concrete, reduction factors linked to service life, temperature and relative humidity were obtained. By utilizing the new approach presented in this paper, more refined and accurate design values for long-term tensile strength of a GFRP bar could be achieved.
10.14359/51682474
SP275-60
Clayton A. Burningham, Chris P. Pantelides, and Lawrence D. Reaveley
This paper presents research that uses novel clamp anchors and a simple mechanical stressing device for post-tensioning carbon FRP (CFRP) composite rods. The CFRP system was used in the repair of prestressed and normal reinforced concrete beams controlled by flexural and shear failure, respectively. The scaled specimens were designed to simulate concrete bridge girders with two different types of field-observed damage—end cracking and damage to internal steel prestressing tendons caused from vehicle collision. The CFRP repair system increased the ultimate strength and proved to be a practical and feasible method of repairing concrete girders with reduced shear or flexural capacity.
10.14359/51682470
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