## 3 Experimental Program  
### Specimen  
For the rotational stiffness of a joint, the rotational stiffness of the vertical axis (R\({}_{y}\)) of the vertical member and horizontal member plane was considered among the three-directional rotations of the joint, as shown in Figure 1. In the tests conducted in this study, a specimen consisted of one vertical member, one horizontal member, and a joint at which a pin at the end of the horizontal member was inserted into a ring attached to the vertical member to connect the two members. The load was applied to the horizontal member in the cantilever state. The opposite moment (-Ry) was not considered in this study. It is noted that the rotational stiffness of the joint in the opposite direction could be different than that of the joint in the tested direction since the end of a horizontal member is not symmetric. A jig attached to the floor was fabricated to fix the vertical member. The jig consisted of a floor plate and a round steel bar, and the vertical member was fixed by inserting it into the round steel bar. The material of the jig was SS400, and the dimensions of the floor plate were 30 mm (height) \(\times\) 200 mm (width) \(\times\) 200 mm (depth). The round steel bar welded to the floor plate was 370 mm in length and 54 mm in diameter (Figure 2). To measure the displacement and angle that varied as the load was applied to each specimen, linear variable differential transformers (LVDTs) were installed on the vertical and horizontal members, as shown in Figure 2. In addition, strain gauges were installed on the joint ring and on the horizontal member to determine the stress in the joint ring and in the horizontal member. Two LVDTs were installed on the bottom of the horizontal member. LVDT1 was installed 200 mm from the joint, and LVDT2 was installed 50 mm from the joint. Strain gauges (S.G.1 and S.G.2) were installed on the top of the horizontal member at the same positions as those of LVDT1 and LVDT2. In the case of the vertical member, two LVDTs were installed 100 mm above and below the connection pin, and two strain gauges were installed (S.G.3 and S.G.4) on the joint ring. \begin{table}
\begin{tabular}{c c c} \hline
**Classification** & **Joint Type** & **Initial Rotational Stiffness (kNm/rad)** \\ \hline [PERSON] [24] & Wedge & 38.92 \\ [PERSON] et al. [26] & Wedge & 71.892 (welded) \\  & & 26.315 (pin) \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._  
Figure 1: Estimated direction of joint rotational stiffness. To reflect the reuse characteristics of temporary materials, experiments on joints were performed using the vertical and horizontal members that had been used before. Specimens must be prepared based on the number of uses to obtain accurate data, but it is practically difficult to prepare specimens based on the number of uses because the history of temporary materials is not managed. Therefore, specimens were constructed by randomly purchasing products made by the same manufacturer from a large leasing company, based on the period of use. Eleven sets of products used for one year, eleven sets of products used for four years, and eleven sets of products used for seven years were purchased. Specimens composed of a vertical member, a horizontal member, and a joint were constructed for the experiments, and a wedge-type joint was employed for all of the specimens. Experiments were also performed with thirteen sets of new members to compare and analyze changes in the moment capacity and rotational stiffness of the joint due to reuse. The specimens considered in this study are listed in Table 2. The New-S-3 and Reused-7-6 specimens were excluded from the analysis because measurement mistakes occurred during the experiment and appropriate data could not be obtained for them.