Fracture analysis of quadruple fastenings with bonded anchors

In order to investigate the failure mechanism and the failure load of quadruple fastenings with bonded anchors a series of numerical investigation was carried out. The studied specimens were bonded anchors in a concrete block and subjected to tensile loading. In the calculations the microplane model with relaxed kinematic constraint was used to simulate the concrete and bond materials. Totally more than 50 calculations were performed. Varied were embedment depth (h.1 = 4d to 20d), spacings between anchors (s = 0.25h.1 to 2.Sh.1), anchor diameter (d = 8, 12 and 20 mm) and bond strength ( r,, = 6.2 to 22.5 N/111111). The results of the numerical studies were compared with the results of experimental investigations. From these studies the failure mechanism of bonded group anchors is clearly revealed and the group effect on the failure load is clarified. Based on the numerical and experimental results a model for evaluating the failure load of quadruple fastenings with bonded anchors is proposed.