# Fire Performance of Self-Tapping Screws in Tall Mass-Timber Buildings
## 2 Materials and Methods
### Methodology  
#### 2.3.1 Small-Scale Fire Test  
In an attempt to characterize the thermal penetration depth of fasteners exposed to fire, the head of the fasteners and the top surface of the 130 mm (width) \(\times\) 200 mm (length) gulam specimens were exposed to a conical radiant heater for one and two hours. Three fiberglass-insulated thermocouples (type G/G-24-KK) were installed parallel to the isotherm at the head of the fastener (0 mm), at its mid-length (80 mm) and at the tip (160 mm). Figure 1 shows the specimen before fire testing with the location of the thermocouples. Each side of the gulam specimen was protected with low-density refractory insulation to limit heat losses. The tests were performed using a cone calorimeter where the vertical conical heating source was calibrated to provide a constant heat flux level of 50 kW/m\({}^{2}\)\(\pm\) 2% at the surface of the specimens located 25 mm away from the heating source (see Figure 2). The vertical orientation was chosen due to size restrictions when using the horizontal orientation and in an attempt to facilitate visual observations during the tests. Only the heating source of the cone calorimeter was used during this study. The STS were positioned in accordance with the distance requirements of the CCMC evaluation report 13677-R [20] (see Figure 3). The fastener was inserted at the geometric center of the original surface of 130 mm \(\times\) 200 mm of the gulam specimens. The exposed head of the STS and the bolts were positioned along the center of the conical heating source and 25 mm away from it (see Figure 1a). The exposed tip of the STS was also positioned at  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Partial-(PT) or** & **Outside Thread** & **Shank** & **Length (L)/Threaded** & **Penetration with Exposed Head** \\
**Full-Thread (FT)** & **Diameter (\(d_{P}\))** & **Diameter (\(d_{min}\))** & **Length (\(L_{F}\))** & **(H) and with the Exposed Tip (T)** \\ \hline PT & 8 & 5 & 160/80 & 160 (H) \\  & 10 & 6.3 & 160/100 & 120 (T) \\ \hline FT & 8 & 5 & 160/143 & 160 (H) \\  & 8 & 5 & 160/143 & 120 (T) \\ \cline{2-5}  & 10 & 6.2 & 160/145 & 160 (H) \\  & 10 & 6.2 & 160/145 & 120 (T) \\ \hline FT \({}^{1}\) & 8 & - & 300/283 & 300/230/171 \\ \hline \hline \end{tabular} \({}^{1}\) STS used for vertical load test.  
\end{table}
Table 1: Dimensions of self-tapping screws.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Fastener Head** & **Shank Diameter (\(d_{P}\))** & **Length (\(L\))/Threaded** & **Lead Hole** & **Penetration** \\
**(mm)** & **(mm)** & **Length (\(L_{F}\))** & **Diameter** & **(mm)** \\  & **(mm)** & **(mm)** & **(mm)** & **(mm)** \\ \hline
23.8 & 15.9 & 140/38 & 16.8 & 150 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Dimensions of bolts (using a 38.1 mm (1 12′′) washer).  
After fire exposure, the specimens were moved to a test machine MTS 50 kN (see Figure 3). In an attempt to limit heat losses during the manipulations, the specimens were wrapped in low-refractory ceramic fiber blankets immediately after fire exposure and until being installed for the pull-through test. All pull-through tests were performed within five and eight minutes after the fire exposure to limit variability between the specimens. Fasteners were pulled out with a hydraulic actuator at a constant crosshead speed of 2.54 mm/min as per ASTM D1761 [28]. The test was stopped after the maximum capacity of the fastener was reached. After testing, the specimens were cut in half to observe and measure the charred layer of the glulam as well as along the fastener's shank.