In-plane and out-of-plane shear characteristics of reinforced mortarless concrete block masonry

Abstract

Mortarless masonry systems can be reinforced and grouted to increase their in-plane and out-of-plane resistance for applications such as in the basement and retaining walls or load bearing walls in buildings. However, limited knowledge is available on the interface and out-of-plane shear strength and corresponding displacement characteristics of reinforced mortarless masonry walls. There are no proper design provisions available for designing mortarless masonry in the Australian Masonry Standards (AS3700). In order to comprehend the interface and out-of-plane shear behaviour of reinforced mortarless masonry, an experimental campaign was conducted in two stages. In the first stage, twelve reinforced mortarless triplets were constructed with two different types of interlocking blocks and reinforcement ratios (main vertical reinforcement perpendicular to bed joint interfaces) and tested under interface shear loading. In the second stage, twenty-four reinforced mortarless panels were built and tested under out-of-plane shear loading with the same types of interlocking blocks, reinforcement ratios and shear span ratios. The experimental results are provided in terms of failure patterns and load-displacement responses retrieved from the tested triplets and panels. The failure patterns of the triplets (under interface shear) and panels (under out-of-plane shear) are governed by the characteristics of dry joints between the blocks. The change in interlocking block types did not greatly influence the behaviour of reinforced mortarless masonry, however, change in the reinforcement and shear span ratios had significantly affected the load-displacement behaviour of triplets and panels. The experimental data established in this study was used to verify the applicability of existing design provisions for conventional reinforced masonry to the reinforced mortarless masonry. It was observed that the provisions outlined in Australian standard (AS3700) are most conservative in predicting the interface and out-of-plane shear strengths of reinforced mortarless masonry triplets and panels, in comparison to the provisions in Canadian (CSA S304-14) and American (TMS 402/602-16) standards.