Design rules for hollow concrete masonry walls subjected to concentrated loads

Abstract

Design rules are proposed for assessing the bearing strengths of hollow concrete masonry walls subjected to in-plane concentrated loads. These are derived from numerical and experimental studies of this problem. Two possible zones of failure are considered: the solid–grouted masonry directly beneath the concentrated loads, and the hollow masonry beneath the grouted portion. The important factors influencing the bearing strength are taken into account: loading eccentricity across the wall width, effective loading area, loading plate length, and loading location along the wall. An angle of 22° or slope (vertical to horizontal) of 2.5:1 is chosen for a safe estimate of the dispersion of concentrated load through the solid–grouted masonry. For partial grouting patterns, at least two courses downward should be grouted to a length compatible with the loading plate. When compared with the available numerical and experimental results, conservative estimates of ultimate strength are obtained in all cases.Key words: design rules, hollow concrete masonry wall, in-plane concentrated load, out-of-plane eccentricities, loading plate length, loading locations, dispersion angle.