Influence of Specimen Geometry on the Response of Post-Installed Anchors Subjected to Constant Load under Crack Opening and Crack Cycles

It is generally acknowledged that one of the most critical tests to capture the behavior of a post-installed fastener under seismic action is the so-called “seismic crack movement test,” which consists in applying a constant load to a single fastener installed in a crack subjected to opening and full closing cycles. This article presents experimental results of crack movement tests on large size post-installed anchors that show a strong influence of the geometry of the concrete specimen in which the anchor is installed. To improve the regularity of the crack plane, a feedback control using the crack opening signal is applied to the servo-hydraulic actuators. Results of seismic crack movement tests using two different test setups were compared. The major aspects are as follows: (i) splitting force generated by the anchor affects the restoring of the zero crack opening when increasing the number of cycles, and (ii) increasing the size of concrete element limits the effects of bending induced in the concrete specimen. The issue of residual crack opening at the zero actuator’s load is observed experimentally and is further approached both analytically and numerically. The parameters that mostly affect the crack closure phase, i.e., steel ratio, transfer length, and de-bonding length, are finally discussed.