Experimental analysis of a new connection system for CLT structures

Constructions with Cross Laminated Timber (CLT) are characterized by a high level of precision, enabled by a high level of prefabrication already at the industrial production and customizing facilities, e.g. by means of computer numerical control (CNC) systems. However, an in-depth analysis of the CLT construction system outlined the mechanical connections as critical point: currently, single panels are preferable connected by means of screws or through hold-down elements and angle brackets which are nailed to the panels, a technique adapted from light-frame timber structures. The innovative system connector X-RAD was designed to replace the aforementioned traditional ways by a connector designed explicitly for CLT structures. XRAD consists of a point-to-point mechanical connection system, fixed to the corners of the CLT panels. This connection, that is designed to be prefabricated, is made of a metal wrapping and an inner hardwood timber element which are both together fastened to the panel by means of fully-threaded self-tapping screws. The paper presents the results of comprehensive test campaigns conducted on the connector by the collaboration of TU Graz, CNR-IVALSA and University of Trento.