Experimental investigation of cracked notched glulam beams repaired with screws

Abstract

Notches made at the ends of glued laminated timber (glulam) beams significantly decrease load carrying capacity of a structural member. This paper presents an experimental research on bending behaviour of end-notched glulam beams, and their bending behaviour after they were repaired using screws. The beams originally failed due to crack opening and their propagation. Cracks that appeared in the notch details resulted from excessive tensile stresses perpendicular to grain and shear stresses. This study showed that repairing the beams at the notched ends post failure can completely restore and even improve their load carrying capacity and successfully tie together the upper and lower parts of the beam separated due to horizontal crack that propagated from the notches towards the middle. Most repaired beams failed in bending while exhibiting ductile behaviour. However, there was no substantial improvement of bending stiffness. This research gives an insight in rehabilitation and repair possibilities of existing structures and it can be a basis for further investigation of strengthening techniques for end-notched solid timber and glulam beams.