## 2 Experiments  
### Experimental Design  
According to Chinese standard GB 50011 \"Code for seismic design of buildings\" [16], the main structure of the building was not damaged and non-structural components (including the infill wall) were not excessively damaged within the elastic story drift limit. Furthermore, the interface between the BLC-C composite wall and the infill wall initially cracked within the elastic story drift limit. Therefore, the experiment conducted in this study focused on the mechanical behavior within the elastic story drift limit.  
According to actual engineering design drawings, the specimens were designed to simulate the walls of a high-rise BLC-C composite wall structure. Two specimens, W1 and W2 were designed to simulate the walls of a high-rise BLC-C composite wall structure.  
Figure 1: Connection structure of the interface (using cement mortar; units in mm).  
Figure 2: Connection structure of the interface (using anti-crack mortar; units in mm).  
W2, were produced and comprised an infill wall and a BLC-C composite wall on both sides. The materials of all BLC-C composite walls were Q355 (nominal yield strength is 355 MPa) steel and C45 concrete (nominal cubic compressive strength is 40 MPa). The infill wall was composed of MU10 burned shale perforated bricks (nominal compressive strength is 10 MPa) and M5 cement mortar (nominal cubic compressive strength is 5 MPa). The specific dimensions of the two specimens are shown in Figure 3. The height of the specimens was 3350 mm. The widths of the BLC-C composite walls of the two specimens were 1730 and 2390 mm, respectively, and the thickness was 130 mm. The BLC-C composite walls were composed of steel tubes of different sizes such as 200 mm \(\times\) 130 mm \(\times\) 4 mm, 130 mm \(\times\) 130 mm \(\times\) 130 mm \(\times\) 8 mm, 130 mm \(\times\) 130 mm \(\times\) 4 mm, and 140 mm \(\times\) 130 mm \(\times\) 5 mm. To distinguish them more clearly, the one near the loading end was referred to as the rear BLC-C composite wall and the other was referred to as the front BLC-C composite wall. The widths of the infill walls of the two specimens were 2440 and 3680 mm, respectively, and the thickness was 200 mm. The structural connection between the BLC-C composite wall and the infill wall shown in Figure 2 was adopted for the test. The thicknesses of the gypsum plaster on both sides of the BLC-C composite wall and the infill wall were 50 mm and 15 mm, respectively.  
Figure 3: _Cont._  
The loading beam and foundation beam were set at the top and bottom of the specimen, respectively. The beams had sufficient strength and rigidity to ensure that no large deformation occurred during the loading process. The steel plates were welded at the ends of the BLC-C composite wall, which was connected to the loading beam and the foundation beam by high-strength bolts. A lateral support was arranged on the loading beam to prevent any out-of-plane behavior of the specimen. The foundation beam was clamped to the ground by ground anchors. In the test, a 500 t jack on the reaction wall was used to apply a unidirectional horizontal load to the loading beam in increments of 100 kN [17]. The elastic story drift angle of a BLC-C composite wall structure should not be greater than 1/400 under wind loads, in accordance with the Chinese standard T/CECS 546 \"Technical standard for structures with concrete-filled multicellular steel tube walls\" [18]. Hence, the experiment was loaded until the drift angle reached 1/400. According to [PERSON] et al. [19], in the elastic stage and elastoplastic stage, the axial load ratio of a BLC-C composite wall had little effect on the strength and stiffness. Moreover, infill walls are non-structural elements and are not subjected to the axial force transmitted from the superstructure. Therefore, the test did not consider the application of an axial load to the specimen. Figure 4 illustrates the field test diagram of specimen W2.