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Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 96 Abstracts search results
Document:
SP230-25
Date:
October 1, 2005
Author(s):
M.J. Chajes, W.W. Finch, Jr., and H.W. Shenton
Publication:
Symposium Papers
Volume:
230
Abstract:
When strengthening concrete structures using externally bonded compositematerial plates, the bond between the concrete and plate typically fails well before theplate’s tensile capacity is achieved. To enhance the bond performance, usingcomposite fabric between the plate and the concrete was explored. Six tensiondevelopment specimens were tested to determine the maximum tensile load that couldbe applied to a CFRP plate before it debonded. Three specimens had a Sika CarboDurstrip bonded directly to the concrete, while three others had the CarboDur strip bondedto two plies of Sikawrap Hex 230C fabric material. The fabric was used to distribute theload over a larger bond area. The specimens without fabric failed at an average load of60.5 kN while the specimens with the CFRP fabric failed at an average load of 92.6 kN.These failure loads represent 18 % and 27.5% of the plate capacity respectively.
DOI:
10.14359/14846
SP230-26
B.M. McSweeney and M.M. Lopez
The sensitivity of the FRP-concrete bond failure load to changes ingeometric and material parameters is described, and initial comparisons to predictionsfrom existing bond models are made. To accomplish this, load and strain data from aseries of single-lap pull-off tests is analyzed, in which carbon fiber reinforced polymer(CFRP) strips of varying width, thickness, and bonded length were pulled from concreteblocks of varying concrete strength. It was found that the concrete compressivestrength had limited effects on the bond failure load, and longer bonded lengthsincreased the time up to failure load. Changes to the bonded width and FRP thicknesshad a significant impact on the bond failure load. Failure load predictions produced bythree studied bond models were found to be strongly influenced by the materialproperties used as input, and were occasionally insensitive to the parameters varied.
10.14359/14847
SP230-27
W.E. El Sayed, U.A. Ebead, and K.W. Neale
With the development of the technology of strengthening existing concretestructures using externally bonded FRP composites, a number of issues related to thestructural behaviour of such structures require investigation. One of the most importantissues is the interfacial behaviour between the FRP composite and the concrete as thisoften controls the failure mode of the strengthened member. Several studies haveprogressed on the development of appropriate interfacial behaviour (bond–slip)models and on understanding the debonding phenomena. This work focuses on thenumerical modelling of FRP-strengthened two-way reinforced concrete slabs where thepredominant mode of failure is debonding at the FRP-concrete interface. An appropriatefinite element model that represents the interfacial behaviour for FRP-strengthenedtwo-way slabs is presented. The proposed model successfully simulates the differentflexural failure modes, particularly those related to the debonding of the FRP sheets.The ultimate load carrying capacity and load–deflection relationships are predictedwith reasonable accuracy.
10.14359/14848
SP230-22
C.A. Coronado and M.M. Lopez
In this study, experimental and numerical procedures are proposed topredict the debonding failure of concrete elements strengthened with fiber-reinforcedpolymers (FRP). The experimental tests were designed to obtain the tensile softeningcurve and fracture energy of the concrete-epoxy interface. Results indicate that thefracture energies of plain concrete and concrete-epoxy interface are different inmagnitude. The numerical simulations were conducted using a plastic-damage model.In this approach, the damage is defined using the tensile softening curve. Numericalresults were validated against experimental results obtained from pull-off bond tests.The numerical models were capable of predicting the experimentally observed load-strain, strain distributions, failure load, and failure mechanism of the pull-offspecimens.
10.14359/14843
SP230-23
D.G. Novidis and S.J. Pantazopoulou
In this paper bond tests conducted on short NSM-bar anchorages arepresented and results are evaluated to determine the effect of design variables ondevelopment capacity. Specimens were designed so as to minimize spurious secondarystresses along the bonded length. Parameters of the study were the groove dimensionsand the embedment length. Bars were CFRP reinforcement with sandblasted surfacecharacteristics. Analytical expressions are derived from first principles so as to interpretthe observed experimental trends. The parameters of the analytical bond stress - slipmodel are calibrated to the experimentally derived bond-slip relationships in order toestablish a limit-state model for post-installed reinforcement, for practical upgradingapplications.
10.14359/14844
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