Cohesive debonding of a stiffener from an elastic substrate

Abstract

To strengthen concrete or masonry, a modern technique uses adherent strips made of Fiber Reinforced Polymer (FRP). A model problem for this is here considered, represented by an elastic stiffener pulled at one end, in adhesive contact with an elastic half space in generalized plane stress. An analytical solution is developed under the hypothesisà la Baranblatt that cohesive adhesion forces remain active between the two materials when relative slip occurs (provided this is less than a critical value), so that the stress singularity predicted by the theory of elasticity in the case of perfect bonding is removed. We find that the bond length beyond which no further increase of strength could be achieved, referred to as the effective bond length, coincides in practice with the ultimate length of the cohesive zone, i.e., its maximal extension prior that the critical slip limit is attained. The debonding process in a pull-out experiment is analyzed in detail. Results are in better agreement with experimental data than those obtainable with traditional models, which neglect as a rule the deformation of the substrate.

Assessment of historical masonry pillars reinforced by CFRP strips

“…In fact, damage processes occurring inside a masonry pillar (expected to be more significant with respect to a concrete support, see [3,9]), are expected to govern the overall behaviour at collapse [10,11]. The case-study here proposed with reference to a CFRP reinforced masonry pillar subjected to single-lap shear test, shows the important capabilities of a synergistic approach combining conventional overall data (reaction force and stroke), with point sensors (LVDTs and clip gauge), non-conventional measurements techniques (namely, single camera 2D Digital Image Correlation) and advanced finite element models.…”

Nonlinear Analytical Procedure for Predicting Debonding of Laminate from Substrate Subjected to Monotonic or Cyclic Load

“…Modeling the global behavior of existing members strengthened in bending by means of bonded FRP laminates is a major topic of interest in practice and it has been extensively researched [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ], but unlike FRP, which behaves linear-elastically until failure, SRP is an elasto-plastic material with strain-hardening characteristics. Consequently, the analysis of SRP retrofitted elements can be relatively more complex than that of FRP-retrofitted elements.…”

“…For example, cohesive debonding of a bonded strip from an elastic substrate has been studied by Franco. and Royer Carfagni [ 10 ] using a model representing a finite stiffener bonded to the boundary of a semi-infinite plate to determine the effective bond length of the stiffener. Cornetti and Carpinteri [ 11 ] obtained an analytical solution by assuming an exponential decaying softening branch for the interfacial bond-slip law.…”