Wall tie research for existing and new structures; literature study

Many square kilometres of outer leaves of cavity walls are made of masonry, supported by wall ties. Wall ties are applied to transfer the forces from the outer leaf to the inner leaf. The quality, the fixation and the number of applied wall ties define the stability of the outer leaves. Occasionally, some of these walls collapse without warning, even though these walls had survived wind loads for decades. This creates a potentially dangerous situation. Nevertheless, it is remarkable that there is still much unknown about wall ties. For instance, many failure mechanisms are not described in literature. Also, important parameters are barely quantified in codes and guidelines. For existing and new structures, new codes concerning wall ties are needed. This should also include environmental aspects. This paper describes a literature study and will provide insight in upcoming research, executed on building sites and in laboratory conditions at the Eindhoven University of Technology.