Load-bearing capacity of single and multi-anchor connections – theory vs results of experimental research (part 1)

The manuscript reviews the methods and mathematical relationships for estimating the theoretical load capacity of steel anchors – both single-anchor (bonded perpendicularly and diagonally to the surface) and multi-anchor systems. Input data for comparative analyses (experimental load capacity of anchors) were obtained from laboratory tests. A total of 62 R-STUDS bonded anchors, made from metric studding M12 threaded rods, made of carbon steel class 5.8, were tested. The scope of the tests included: 22 single anchors bonded at an angle of 90° to the concrete surface, 12 single diagonal anchors (4 anchors at 30°, 45° and 60° each), 16 anchors in twin-anchor systems at 30° and 45° angles, and 12 anchors in three-anchor systems (2 diagonal anchors at an angle of 60° and one at an angle of 90°). Laboratory tests, with the use of the HYSDOZOK hydraulic load-setting system, were carried out at Bialystok University of Technology in three stages. Comparison of the actual anchor load capacities (experimental load capacities) with the corresponding theoretical load capacities in each of the tested anchor groups showed very large discrepancies in the results (from -97.2% to +139.5%). Most of the results obtained indicate higher values of theoretical anchor load capacity (Pult) than experimental load capacity (Pexp). Further work on adjusting the mathematical relationships used to estimate the load capacity of steel anchors was needed. However, due to limitations in the size of the current manuscript, the results of work related to the application of heuristic algorithms to optimize the mathematical models will be presented in the authors' next publication.