*4.2. Damage Mechanism*

For the global and local analysis of parametric FE results, a key role is assigned to the detailing of stress peaks distributions and damage initiation/evolution in all the joint components. For the examined TTC configurations, the collapse detection of PO specimens was typically associated to a combination of:


A relevant example is proposed in Figure 9 (S#1 specimen with α = −15◦ , at an imposed slip *s* = 12 mm). In the direction of the grain, the wooden fibers were generally subjected to high stresses peaks in a limited region only, when moving far away from the fasteners. This can be noticed in the crushed (red) regions of Figure 9a. The STSs in use, moreover, commonly failed due to the occurrence of two plastic hinges (Figure 9b), and this is in line with the experimental observations reported in [6]. For all the examined TTC joints, finally, a primary role was recognized for the CZM contact, being responsible of the final slope for the collected force-slip curves. In Figure 9c, in this regard, the non-dimensional CSMAXCRT parameter is shown (1 = fully damaged or 0 = undamaged interface). This parameter, for most of the examined joints, was observed to reach its maximum unitary value of failure with an extension up to <sup>≈</sup> <sup>1</sup>/3rd the nominal length L for the STSs in use. <sup>≈</sup>

**Figure 9.** *Cont*.

α

α −

α − **Figure 9.** Typical damage propagation in the selected TTC joints with inclined STSs, under a standard PO setup (ABAQUS/Explicit). Example for the S#1 specimen with α = −15◦ , with evidence of: (**a**) local damage of timber (stress values in Pa), (**b**) yielding of screws (stress values in Pa) and (**c**) CZM damage parameter. Reproduced from [21] with permission from Elsevier®, Copyright license number 4895820420991, August 2020.

#### **5. Mechanical Characterization of TTC Joints**
