Comprehensive study on the pull-out strength and failure pattern of cast-in bottom expansion anchors in thin ultra-high performance concrete panels

Ultra-high-performance concrete (UHPC) has garnered significant attention in the construction industry owing to its superior mechanical performance and aesthetic qualities. Thin UHPC panels have been widely adopted in architectural applications, providing both aesthetic and structural performance. A novel connection method employing embedded anchors with specially designed bottom expansions to secure UHPC panels to supporting structures has been shown to be highly feasible through experimental investigations and numerical simulations. The experimental results highlighted the significant influence of embedment depth on anchor pull-out strength, showing that doubling the embedment depth increased the pull-out capacity by approximately 1.85 times, with failure predominantly governed by conical concrete breakout at angles ranging from 22° to 26°. Numerical simulations closely reproduced the load–displacement behavior and failure mechanisms observed in the experimental specimens, thereby confirming their reliability in representing anchorage performance. • The bottom expansion anchor provides a new way to connect thin UHPC panels. • Pull-out strength depends on anchor depth and bottom diameter. • Failures occur as concrete breakout with cone angles of 22 0 – 26 0 . • Pullout strength grows 33% with 50% larger diameter and 50% with 25% deeper depth. • The finite element model quite accurately predicts anchor behavior in UHPC panels.