American Society of Civil Engineers


Brittle Failure and Bond Development Length of CFRP-Concrete Beams


by Dai Minh Nguyen, Ph.D., (Student, School of Civ. and Struct. Engrg., Nanyang Tech. Univ., Singapore 639798), Toong Khuan Chan, (Asst. Prof., School of Civ. and Struct. Engrg., Nanyang Tech. Univ., Singapore 639798), and Hee Kiat Cheong, (Prof., School of Civ. and Struct. Engrg., Nanyang Tech. Univ., Singapore 639798)

Journal of Composites for Construction, Vol. 5, No. 1, February 2001, pp. 12-17, (doi:  http://dx.doi.org/10.1061/(ASCE)1090-0268(2001)5:1(12))

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Document type: Journal Paper
Abstract: The performance of a series of 1.5 m-long reinforced concrete beams with CFRP plates bonded to the soffit is presented. Effects of the plate length, the reinforcing steel ratio, and the thickness of the concrete cover on behavior of the beams are discussed with particular emphasis on the brittle failure mode of the concrete ripping. It was found that before the brittle failure, the composite action of the beam could be divided into three distinct zones based on the distribution of the strains along the CFRP plate: (1) The “destressed” zone, (2) the “bond development” zone; and (3) the “fully composite” zone. Concrete ripping may be prevented by limiting the strain at the transition point of the composite zone of the plate. An analytical formulation to predict the failure load corresponding to the concrete ripping failure mode is proposed based on composite theory in combination with a strain limiting criterion. The strain limit can be determined based on simple bond tests with various bond lengths for a given CFRP and adhesive combination.


ASCE Subject Headings:
Beams
Brittle failures
Composite materials
Fiber reinforced plastics
Plates
Reinforced concrete