A multi-layer parallel crack extension model for deformational response of post-installed anchor

Abstract

A simultaneous crack extension pull-out model for post-installed anchor bar is presented. The anchor bar is such that used in various strengthening techniques to strengthen reinforced concrete structures. The properties of the infill material used for post-installed anchor bar are characterized by a nonlinear interface between the surrounding concrete and the anchor bar. This is a new type of anchor-infill assembly in which the infill material is divided into two layers for the purpose of providing a larger failure path length resulting in increase of the energy absorption and pull-out load capacity. The mechanical properties of the infill layer are different from the surrounding concrete. Therefore the existing pull-out model of deformed bars cannot be applied directly in this case. The interfacial de-bonding is examined by the strength criterion expressed in terms of interfacial shear stress. Pre-existing cracks representing artificial notches are assumed at the top of infill layers for identifying crack location and stabilizing its propagation direction. All the possibilities associated with two-cracks in the close vicinity have been investigated in detail. The objective of the analysis is to predict a set of material properties which result in simultaneous crack extension at the two interfaces and also to identify a simultaneous crack extension length which results in increasing the pull-out load capacity, increase in energy absorption and increased failure path length but achieved at lowest increase in pull-out deformation thereby proving the effectiveness of two-layer model. Limiting the pull-out deformation is desirable from the point of view of limiting damage.