Experimental investigation on mechanical performance of semi-rigid joints in reticulated glulam shells

A typical joint detail in Kiewitt-6 reticulated glulam shells was designed, and 12 full scale joints were manufactured. Bending tests were conducted on the joints under different amplitudes of axial compression loads, including four load cases of 0, 100, 200 kN and 300 kN, respectively. The bending stiffness and bending capacity of joints were evaluated, and the relationships between moment and rotation and between the failure modes of joint zone and the amplitude of axial force also were studied. It is found that three different failure modes in the glulam members of the joint zone might happen, including the failure in the compression zone of glulam member, failure in the tension zone of glulam member and the boundary failure involving failure in both the compression and the tension zones of glulam member. The bending capacity of joint with tensile zone failure increases with the increase of the amplitude of axial compressive force. The initial bending stiffness of joint increases with the increase of the amplitude of axial compressive force. The bending capacity of joint with failure in compressive zone of wood member is larger than that with failure in tensile zone of wood member. From the obtained moment-rotation test curves and regressed equations of joints under different amplitudes of axial compressive force, it is found that the moderate amplitude of axial compressive force applied on wood member is beneficial to enhance the ductility of joint.