Concrete breakout capacity of tension‐loaded fastenings in narrow concrete members

Abstract Fastenings installed in narrow members such as beams or columns are frequently used in practice. Due to a significantly reduced projected area, the concrete breakout capacity calculated as per the concrete capacity (CC) method for such fastenings can be drastically reduced. This makes it all the more important to determine the capacity of fastenings in such applications as realistically as possible. Through a systematic experimental and numerical campaign, which was performed within the framework of the dissertation by Stehle (2024), the breakout strength of tension‐loaded fastenings in narrow concrete members was studied. For the investigated cases, the current calculation approach as per the CC method yields conservative estimates of the failure load of fastenings in narrow members with two parallel close edges and equal edge distance on either side of a fastening. The experimental and numerical results and the data available in the literature are utilized to develop a realistic design approach, which considers certain modifications to the current CC method for better prediction of the concrete breakout capacity of fastenings in narrow members. The approach proposed in this work can be considered analogous to the approach followed for the design of fastenings under shear in thin members.