Enhanced Ductility of Masonry Shear Walls Using Laterally Confined (Self-Reinforced) Concrete Block

Abstract

<p>The aim of the study presented in this dissertation was to investigate a new method of improving the ductility of masonry shear walls by means of confinement. This proprietary method, referred to as Self-Reinforced Concrete Block (SR Block) employs a previously untried technique of molding lateral confining devices into concrete block. This internal reinforcement provides lateral confinement to the enclosed volume of block and grout material. The resulting triaxial state of compressive stress under axial load allows the confined material to maintain high compressive capacity while undergoing high axial compressive strains. The results from a proof-of-concept program indicated improved plasticity due to the presence of the confining devices within the block. Despite spalling of the unconfined portions of the block at high strains, the SR Block specimens retained load carrying capacities in excess of the peak capacity of similar unreinforced/unconfined block prisms at strains beyond 2% with no visible damage to the confining devices or to the confined material. Further to this proof-of-concept study, an experimental program was undertaken involving additional prism tests as well as testing of shear walls constructed with the SR Block. This program proved the efficacy of a second confining device design in enabling prisms to retain compressive load capacity to strains over six times larger than that of standard grouted masonry. Additionally, the results of the shear wall program indicated that these desirable characteristics were effective in a wall configuration and led to significant increases in the displacement ductility of the walls when compared to similar, unconfined walls. The data presented is expected to serve as a basis for future testing and acceptance of SR Block as a method of increasing the compressive strain capacity of reinforced masonry in order to improve the ductility of masonry shear walls as a lateral force resisting system.</p>