Forming a predictable flexural mechanism in reinforced wall elements

Trasborg P, Nickerson J, Naito C, Olmati P, Davidson J.  Forming a predictable flexural mechanism in reinforced wall elements. ACI Structural Journal 2014; 111(6):1481-1490.

ABSTRACT

Precast concrete exterior cladding elements designed to be under-reinforced results in yielding of the reinforcing steel when subjected to out-of-plane demands. Ultimate failure of the panel, however, is often controlled by compression failure of the concrete. In extreme circumstances where the ultimate obtainable deflection is of paramount importance to dissipate energy, such as in a blast event, the global ductility of the panel may be limited by the failure of the compression zone. To improve the performance of thin concrete elements subject to extreme loading scenarios, a failure mechanism that is both ductile and predictable must be developed. In this paper, two different flexural mechanisms have been examined: (1) a deformable steel inlay mechanism on the tensile face of the panel and (2) locally unbonding the flexural reinforcement in the hinge region. Each flexural mechanism investigated successfully increases the global ductility of the concrete panel in a predictable manner.

Keywords: Debonding; Mechanical Bond; Precast Concrete; Reinforced Concrete; Reinforcement; Ultimate Load; Wall