Design of anchor bolts in masonry

Abstract

AbstractA review of the methods used to design anchors for masonry in Canada, Australia, New Zealand, Europe and the United States was conducted. It was determined that with the exception of the American standard (MSJC), most provisions for connections for masonry require anchors to be designed using some form of performance based criteria.The MSJC uses design equations to predict anchor behavior and an evaluation of these equations using recent published test results suggests that the nominal tension anchor bolt capacity equations appear to give relatively good results at smaller anchor diameters. However, unaccounted for tension splitting/flexural modes appear to be present in larger anchor diameters.The investigations also suggest that the shear load provisions in the MSJC appear to be adequate when predicting the capacity of smaller diameter bolts, but they can be very unconservative for shear load capacities for bolts above 19 mm in diameter. The masonry break out equation does not appear to accurately predict the splitting/prying masonry failures observed with these large diameter anchors. In addition, it appears that splitting failures may occur in smaller masonry assemblies and further work must be conducted to determine if this is a testing protocol artifact or a failure mode that can be realistically expected in the field such as the proposed shear bearing model.Finally, results of combined shear and tension load tests, appear to suggest that the interaction equation for anchors used in grouted cavities in masonry assemblies is a power function, with a value between 1.4 and 1.67.