# Seismic Design Procedure for Low-Rise Cold-Formed Steel-Special Bolded Moment Frames
## 3 Full-Scale Testing Program  
In this study, five full-scale specimens were prepared, and cyclic loading was conducted. The configuration of each specimen is summarised in Table 1. The table includes information on the bolt strength, joint type, surface class, and beam location. Each specimen's section profile in the columns, beams, and plates was the same. The column was  
Figure 3: Required strength at the beam-to-column connection. a square hollow structural section (HSS) with dimensions of 250 \(\times\) 250 \(\times\) 6 (mm), the built-up beam was 2C with dimensions of 400 \(\times\) 75 \(\times\) 6 (mm), and the connecting plate was PL with dimensions of 400 \(\times\) 710 \(\times\) 12 (mm). The column size determined the toe-to-toe separation in the built-up beam; it was decided that it would be 100 mm (=250 \(-\) 75 \(\times\) 2) in this test. The test parameters were the joint type, surface class, and beam location. The AISI standard stipulates that the beam-to-column connections of CFS-SBMFs be \"snug-tightened high-strength bolts\" [1]. Following this requirement, high-strength bolts with snugly tightened conditions were used as a parameter. Two classes of high-strength bolts were available for use: ASTM A325 and A490 [15]. In this study, the bolt strength F10T class (\(f_{u}\) = 1000 MPa), equivalent to A490, was selected as the default. Additionally, in practical applications, high-strength twist-off bolts (i.e., ASTM F1852 and F2280) are more widely used due to their easier installation. Once the tail of these bolts is twisted off, a specific amount of pre-tension is installed in the bolt [15]. Therefore, pre-tensioned conditions were also included as a parameter. The condition of the faying surface is also an essential aspect of the structural performance. AISI [1] also stipulates that \"the faying surfaces of the beam and column in the bolted moment connection region are free of lubrication or debris\", which corresponds to a Class A surface (i.e., a mean slip coefficient \(\mu\) equal to 0.3) [15]. Therefore, as the default, an unpainted clean mill scale steel surface was used. For specimens 1 to 4, the bolt strength F10T with a Class A surface was used. For the beam location, one-sided beam-to-column connections (OSs) were prepared to simulate an exterior column. Both-sided beam-to-column connections (BSs) were prepared to simulate an interior column. If a bolted connection has sufficient strength to lead to the beam yielding, unexpected behaviour will occur. To simulate this situation, the BS_02 specimen was recycled by changing the surface conditions and bolt class to create the BS_03 specimen. For the BS_03 specimen, a Class B surface (i.e., a mean slip coefficient \(\mu\) equal to 0.5) [15] and F14T class bolts (\(f_{u}\) = 1400 MPa) were used. The bolt strength F14T, which is manufactured for use in building structures, can only be found in the Japanese market. The mechanical properties of the members obtained in coupon tests are summarised in Table 2.  
The experimental setups for the OS series and BS series specimens are shown in Figures 4 and 5, respectively. The beam was assumed to have a length on each side of the column that was equal to half the bay width, with the inflection point in the middle. The bay width was assumed to be 6.0 m. Moreover, it was assumed that the middle of the storey height was the inflection point for the columns; the storey height was assumed to be 3.0 m. The beams were attached to the connecting plates using high-strength bolts with a diameter of 20 mm and standard bolt hole dimensions of \(d\) + 2 mm, as shown in Figure 6. Figure 6 also shows the bolted joint configuration. The bolted joint configuration shown