Reduction of perpendicular-to-grain stresses in the apex zone of curved beams using glued-in rods

This paper reports a finite-element-based study of the reduction, using glued-in rods, of the perpendicular-to-grain stresses in the apex zone of curved beams in glulam structural timber members. Currently, the design of this type of elements is conducted using simplifying assumptions about the perpendicular-to-grain stress distribution in the apex zone, which start out from the calculation of the parallel-to-grain stress distribution and apply some corrector coefficients to it, confirmed by years of experience and studies. This work presents a practical approach, by conducting a numerical simulation of the behavior of these stresses in the apex zone with the presence of glued-in rods, which enables optimization in the design of this type of assembly. The finite element results demonstrate the importance of the features, number and positions of the glued-in rods.