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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:
SP275-70
Date:
March 1, 2011
Author(s):
G. Dalfre and J.A.O. Barros
Publication:
Symposium Papers
Volume:
275
Abstract:
Two types of arrangements of NSM CFRP laminates for the flexural strengthening of continuous RC slabs were investigated, one with CFRP laminates exclusively applied in the intermediate support, H series (hogging region), and the other with laminates applied in both the hogging and sagging regions (HS series). In the H series the increase of load carrying capacity was limited to 10% (for a target value of 25%) and 17% (for a target value of 50%), and the moment redistribution capacity () did not attain the target value (30%) and has decreased with the increase of the CFRP strengthening ratio. In the HS series the increase of load carrying capacity has exceeded the target value (25%) and the moment redistribution capacity was not significantly affected. For the HS series the flexural strengthening effectiveness was limited by the detachment of the concrete cover that includes the laminates, at the hogging region.
DOI:
10.14359/51682480
SP275-65
Yoseok Jeong, Anurag Jaipuriar, Maria M. Lopez, and Charles E. Bakis
Most of the recent research on the bond characteristics of the concrete-FRP interface involves short-term behavior which may not be indicative of bond behavior following sustained forces on the adhesive joint, particularly in the case of ambient-curing adhesives which can take weeks to reach their full strength capability. The objective of the research effort is to investigate the effects of sustained loads and various temperatures on the bond behavior of FRP sheets bonded to concrete. The approach involves experiments and numerical analysis. The model was parameterized with experiments on the concrete, FRP, interface, and epoxy. Good correlation was seen between the numerical simulations and pull-off experiments. Parametric studies shed light on the influence of temperature, epoxy modulus, and epoxy thickness on the redistribution of interfacial shear stress during sustained loading. This investigation confirms the hypothesis that interfacial stress redistribution can occur due to sustained load and elevated temperature and its effect can be significant.
10.14359/51682475
SP275-66
H. R. Hamilton, C. W. Dolan, J. E. Tanner, and E. P. Douglas
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.
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
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