Behavior of reinforcing bar connections of hollow-core slabs to masonry walls under in-plane forces

Abstract

Integrity ties are necessary in hollow-core slab floors as connections to prevent floor displacements under lateral loads and maintain the overall structural integrity of buildings. In Eastern Canada, the integrity tie for hollow-core slabs on masonry walls usually consists of a 10M (no. 3), L-shaped steel bar that is hammered into the supporting wall and grouted to the slabs. However, current North American design codes do not offer sufficient provisions to determine the capacity or predict the mode of failure of these ties and connections. This paper introduces the results of testing nine full-scale reinforcing bar connection assemblies under monotonic in-plane forces (compression, tension, and shear) until failure. Test parameters in this study included direction and orientation of the in-plane loading, the bearing type of the hollow-core slabs, and the use of adhesive. Test results showed that connections with dry-fit bars tested under compression failed by bar yielding followed by masonry beam crushing. In addition, the mode of failure under tension forces was governed by the loss of bearing of the slabs due to bar pullout and cover spalling. Under shear forces, the connection failed by bar yielding. Finally, the connections with adhesive had a similar mode of failure compared to their counterparts with dry-fit bars, but these did not show bar pullout from the masonry beam, therefore demonstrating higher stiffness.