Synopsis
March 2010 saw the introduction of new structural design codes across Europe and from that date existing British Standards were no longer updated and maintained. BS 5628: Part 1:2005, the existing British Standard on unreinforced masonry was replaced by EN 1996-1-1:2005 and its associated National Annex. In this paper comparisons between these British and European standards have been undertaken to evaluate differences between strength predictions with respect to vertically loaded walls. Standard size clay and calcium silicate bricks and aggregate concrete and aircrete blocks 215mm high and of thickness: 100, 140, 190 and 215mm are included. Initially comparisons to highlight differences between the various separate procedures, which feed into the wall strength design procedures in each code, are undertaken. Comparisons of wall strength are made to indicate the overall differences between the two codes when predicting wall resistance.
Results indicate that each of the separate procedures that make up the overall design differ, and in the case of estimating unit characteristic strength differences of up to 50% exist. More importantly though, the overall design resistance of vertically spanning walls when compared using the two codes differ by up to (and in one case more than) 50%. Whilst it is acceptable that individual components of the design process could differ, when combined to give an overall wall strength, they should be broadly similar. This is not the case. However, it should also be noted that in this paper some unit strengths outside what may be expected in practice are included. Nevertheless, the majority of the comparisons could and do arise in industry. Furthermore, this study only examines wall resistances, the impact of how loads are determined.