Mechanics of plain and retrofitted traditional timber connections

The rehabilitation of old historic buildings often requires retrofitting traditional timber connections. Experimental and numerical methods were used in this work to study the elastic and postelastic behavior of the birdsmouth joint, which is used with great frequency in old timber roof structures, especially in the Mediterranean and Alpine legions. After a preliminary inspection of several buildings to acquire data on existing assemblages, an experimental program of testing full-scale samples under monotonic and cyclic loads was undertaken. Different configurations with parameters related to geometry, loading, and material properties were studied using a finite-element model of the connection; the results were calibrated with experimental results. The behavior of various joints was also investigated using a simplified physical model. The leading roles of friction, axial compression, and joint dimensions in determining the joint capacity and postelastic behavior have been highlighted and quantified. Different types of retrofitting methodologies based on the insertion of metal parts were examined and compared on an experimental basis.