A structural reliability analysis was performed on concrete masonry under concentric axial compression to examine the reliability levels for masonry buildings designed to the current Canadian masonry standard CSA S304.1-04 (2004). The first order second moment method was used to carry out the analysis. Prism compressive strength for hollow and grouted concrete masonry was used as the model. Over 300 specified masonry compressive strength values were computed using test results available from North American investigations, mostly Canadian. The material and geometry statistical data needed were obtained from several Canadian concrete masonry producers. Based on the findings of this investigation, it is recommended that unreinforced masonry be assigned a material resistance factor (Φ_m) different from reinforced masonry. For masonry members under compression, it is proposed that the current Φ_m be increased from 0.6 to 0.65 for reinforced masonry and decreased from 0.6 to 0.5 for unreinforced masonry. The proposed factors correspond to reliability indices of 3.5 and 3.8 for reinforced and unreinforced masonry, respectively.
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