Delamination tests on CFRP-reinforced masonry pillars: Optical monitoring and mechanical modeling

Abstract

In this methodological study, delamination phenomena of Carbon Fiber Reinforced Polymer (CFRP) strips from masonry pillars were investigated on the basis of single-lap shear tests. The masonry pillar considered in this case was constituted of three historical bricks, derived from a XVII century rural building. The bricks were bonded by a high strength mortar recently proposed for the restoration process. To follow the specimen response up to collapse, the test was controlled by a clip gauge located at the anchorage of the reinforcement strip. The conventional experimental information, concerning the overall reaction force and relative displacements provided by point sensors (LVDTs and clip gauge), were herein enriched with no-contact, kinematic full-field measurements provided by 2D Digital Image Correlation (2D DIC). Special care was devoted to improve the precision of the optical measurement, which included correction of the effects owing to the lens distortion and to lack of coplanarity between the camera sensor and the monitored flat surface. The overall accuracy was assessed through laboratory benchmarking tests. Moreover, an advanced three-dimensional mechanical model based on nonlinear finite elements was developed under the simplifying assumption of perfect adhesion. This model was adopted to describe bulk damage inside the heterogeneous specimen and to correlate it to the macroscopic response and surface measurements. Coherence between the above mentioned sources of information and the predictions provided by the advanced finite element model were critically discussed.