In-situ installation safety of post-installed anchorages—Investigations on construction sites

Abstract

The sensitivity to reduced installation effort of post-installed fastening systems is determined during the product qualification through robustness tests conducted under controlled laboratory conditions. Using the concept of required α-factors, the installation safety factor γ_inst is determined and provided as an essential characteristic in the corresponding European Technical Assessment (ETA) of the fastener. The purpose of robustness tests is to simulate reduced installation conditions. To gain more insight on the variability of the installation conditions in practice, an in-situ verification of the installation safety factor is carried out on four different construction sites in Austria using four anchorage types to cover all working principles. For this in-situ verification, the obtained ultimate loads from unconfined pull-out tests on-site are compared with corresponding ultimate loads from reference tests under laboratory conditions. Based on the in-situ tests, it is verified if the designed robustness tests are sufficiently appropriate to cover in-situ variations during the installation. The investigation shows that for all tested fastening products, the specified installation safety factor from the ETA could be confirmed with the in-situ tests based on mean values. As expected, the coefficient of variation of the in-situ tests is for torque-controlled mechanical fasteners around two to three times higher than in the laboratory tests, for concrete screws and bonded anchors, the value 1.5 applies.