Experimental longitudinal shear testing of novel and traditional shear connectors in double-wythe cavity masonry walls

Abstract

Double-wythe cavity masonry walls are made of two masonry layers (wythes) – an inner structural wythe typically made from concrete masonry units and an outer façade layer usually made from bricks. Insulation layer and an air gap exist between wythes. Connectors transmit load from the façade to the structural layer. Connectors are typically designed to carry axial forces, but not shear. Their ability to transmit shear, however, is important to achieve composite behaviour between wythes and increase wall capacity under out-of-plane loads. In this study the performance of a novel inclined connector is examined, along with more traditional connectors, through longitudinal shear testing in 38 double-wythe, small-scale specimens. Test parameters include plate connector orientation (horizontal and vertical), tie embedment length, and veneer type (concrete brick, clay brick). The traditional connectors are made of slotted steel plates. The novel connector is also made of slotted steel plates but placed at an inclination in the cavity. The inclination better utilized material making it reach larger stiffness and strength than traditional plate connectors. With the intention of increasing the resistance of the system, ties with various embedment lengths were used with the vertically placed traditional and novel connectors. The stiffness and strength of the novel connector were significantly larger than the vertically and horizontally oriented traditional connector. The larger strength of the inclined connector enables it to be utilized with wider spacing in a full-scale wall compared to a traditional plate connector, leading to potential savings in materials and labour. Failure of the novel connector was a combination of buckling and pullout of the ties, while that of the traditional connector was due to twisting.