Bearing Capacity of Anchors at Multi-cyclic Dynamic Loads

Abstract

Most frequently used types of anchors were subjected to experimental studies to obtain valid data on post-installed anchors, such as mechanical anchors (wedge expansion anchors, undercut anchors, screw anchors, push-in anchors, etc.); bonded anchors (epoxy resin, polyurethane, polyester anchors with quartz sand, cement mixtures added, etc.), and plastic anchors (plastic dowels, plate anchors) and cast-in-place anchors (bent anchors, anchors with an anchor plate, with a conical end, with a bar hook; compound anchors, etc.). The authors studied the effect of an earthquake-induced damage (plastic deformation) of a concrete base and multi-cyclic dynamic loads, similar to seismic ones, on the bearing capacity of anchors and scatter of acquired results. Plastic deformations of the concrete base are assumed to be in the form of cracks located directly at the point of anchoring. The results of the research show that decrease in bearing capacity in cracked concrete under multi-cyclic dynamic loads should be taken into account during design of anchorage under seismic loads depending on failure mechanisms, e.g. for steel failure reduction of bearing capacity does not exceed 6% whereas for failure at the interface between the adhesive composition and the base it can reach up to 50%. Values of variation coefficient depend on type of failure mechanisms, e.g. for steel failure its value does not exceed 5.2%, whereas for interface failures it can reach up to 17.4%. Acquired values of variation coefficients should be taken into account for calculation of safety factors for different types of anchors under seismic loads action.