Critical reaction forces of glulam members with tension-side notches at end supports

Abstract

Tests were carried out on softwood structural glued-laminated-timber (glulam) members to calibrate a linear elastic fracture mechanics design method for bending members having tension-side end notches. Fifty-eight specimens with depths up to 646 mm represented 11 combinations of member size, notch depth, member geometry, loading arrangement, and glulam type. Specimens were loaded until they sustained significant damage at or near notch locations, but none of them failed as bending members. Notch damage started with creation of short stable cracks parallel to the laminations and ended with episodically crack growth. Typically, crack initiation is at about half the load level associated with episodic crack growth. Contrary to current design practice loads positioned close to notched end supports were found to influence strengths of members significantly, and their effects should be taken into account. The findings have been implemented in the 2014 edition of CAN/CSA Standard 086 “Engineering Design in Wood”.