Delamination effects on cracked steel members reinforced by prestressed composite patch

Abstract

Prestressed composite patch bonded on cracked steel section is a promising technique to reinforce cracked details or to prevent fatigue cracking on steel structural elements. It introduces compressive stresses that produce crack closure effect. Moreover, it modifies the crack geometry by bridging the crack lips and reduces the stress range at crack tip. Fatigue tests were performed on notched steel plate reinforced by CFRP strips as a step toward the validation of crack patching for fatigue life extension of riveted steel bridges. A debond crack in the adhesive-plate interface was observed by optical technique. Debond crack total strain energy release rate is computed by the modified virtual crack closure technique. A parametric analysis is performed in order to investigate the influence of some design parameters such as the composite patch YoungÕs modulus, the adhesive thickness and the pretension level on the adhesive-plate interface debond.

Fatigue crack growth in CFRP-strengthened steel plates

“…Reinforcement debonding is then the dominant failure mode of strengthened steel member. In particular for fatigue strengthening crack mouth, debonding plays an important role as clearly demonstrated in [23][24][25]. The presence of a debonded area in the crack tip region significantly reduces the effectiveness of the reinforcement technique and should be taken into account in the evaluation of the fatigue lifetime.…”

Maintenance Actions to Address Fatigue Cracking in Steel Bridge Structures: Proposed Guidelines and Commentary

“…A number of studies have looked at the application of CFRP plates as a type of doubler material for fatigue prone details in steel bridges as a way of providing an alternative load path, bridging over the crack, and reducing the stress range in the critical detail (Bassetti et al, 1999;Colombi & Fava, 2015;Colombi et al, 2003; Ghafoori et al, 2015;Kaan et al, 2008). The results from these different studies are generally in agreement showing that fatigue life can be extended by reducing the stress range or dropping the mean stress by adding the CFRP doubler plates at the critical detail slowing crack initiation and propagation.…”

“…The adhesive layer thickness is important because as it becomes thicker, the shear deformations within the layer increase and as the deformation in the adhesive layer increases, the crack bridging diminishes allowing greater crack opening and a higher stress intensity factor at the crack tip. This was especially true for long cracks (Colombi et al, 2003). Bennett et al (2014) investigated fiber reinforced polymer (FRP) materials for applications in in-plane tensile loading, in-plane bending loading, and distortion-induced fatigue loading.…”

CFRP reinforcement adhesive joint performance on the transversely damaged steel elements under axial tension

“…From the condition (5) of limiting shear stresses in the adhesive, it is easy to obtain a constraint on the applied force P. 11 21 as…”

“…At that, the resistance of the carbon fiber to stretching is many times higher than that of steel, and the Young's modulus may be close to or even much higher than that of steel [5]. The application of CFRPs in building structures strengthening is also considered in [6][7][8][9][10][11][12][13][14][15].…”