3D FE analysis of anchor bolts with large embedment depths

In the present paper the results of a finite element study of single headed stud anchors loaded in tension (concrete cone failure) are discussed. Anchors with extremely large embedment depths (up to 1500 mm) for which few experimental data is available are investigated. Many such anchors are used in engineering practice, therefore, the aim of the study was to investigate their safety. The numerical analysis is performed using a three-dimensional finite element code based on the microplane model. Calculated concrete cone capacity for large anchors with small heads shows good agreement with the current LEFM based design formula for anchors. The numerical study and the available test data show that the ultimate strength of anchors with larger heads is higher than predicted by the design code formula. Furthermore, the size effect on the ultimate load of these anchors is less pronounced. It is shown that the current design formula is conservative for anchors with large heads. A correction factor is proposed to account for the effect of the size of the headed stud and to improve design formula. Further theoretical, experimental and numerical work is needed to investigate the performance of large single anchors and anchor groups and to verify and improve current design recommendations.