2015 CSCE Annual Conference Regina - Building on our Growth Opportunities Conference
Dr. F. Hashemian, University of Manitoba
Mr. Myron Britton, University of Manitoba
Conventional concrete masonry assemblies using hollow Concrete Masonry Units (CMU) are reinforced by bonding reinforcing bars within the cores using masonry grout. This locates the reinforcing bars at or near the masonry system’s out-of-plane neutral axis. The innovative Surface Reinforced Concrete Masonry Unit (SRCMU) uses vertical channels in its external faces to allow near-surface-mounting (NSM) of reinforcement. This hollow concrete masonry construction method allows greater flexural strength to be achieved while reducing the over-all weight of the concrete masonry assembly by 50% due to the elimination of grout filling of the cores. This fosters significant construction cost savings and reduced environmental impact. A comparison of masonry systems utilizing the SRCMU with NSM reinforcement and conventional hollow concrete masonry systems was performed using the CSA S-304 for out-of-plane loading conditions. Under conditions of combined axial and out-of-plane flexural loading, the SRCMU masonry systems had an increased flexural capacity of up to 30% over the conventional concrete masonry systems with the same reinforcement ratio and effective cross sectional area. Numerical modelling and physical testing of unreinforced conventional masonry prisms and SRCMU prisms showed that they have similar behaviour and modes of failure under axial loading conditions. SRCMU flexural specimens reinforced using epoxy-grouted reinforcing bars were tested under 4-point bending. Steel reinforced specimens achieved an average resistance that matched the prediction from the CSA S-304 analysis; this demonstrates SRCMU systems can achieve greater load carrying capacities with less material while maintaining modes of failure and design characteristics similar to conventional CMU construction.