## 3 Results of Cyclic Loading Tests
### Load-Displacement Relationship  
Figure 9 shows the graphs of the load-displacement relationship of each specimen. In BF, flexure failure occurred. The maximum force in the positive and negative directions  
Figure 8: Failure of columns. (**a**) BF, (**b**) IF-0.5, (**c**) IF-1.0. Figure 7: Gap closure due to lateral displacement (IFS-1.0). was 203 and \(-\)199 kN, respectively, which are similar to each other. Additionally, the maximum drifts, defined as the drift when the force decreased to 80% of the maximum force, were 5% and 4.9% in the positive and the negative directions, respectively. \begin{tabular}{l l} \(P_{u}\): & Maximum force \\ \(P_{f}\): & 80\% of \(P_{u}\) \\ \(D_{u}\): & Drift at \(P_{u}\) \\ \(D_{f}\): & Drift at \(P_{f}\) \\ \end{tabular}   
Figure 9: Force vs. drift curves. (**a**) BF. (**b**) IF-0.5. (**c**) IFS-0.5. (**d**) IF-1.0. (**e**) IFS-1.0. The maximum strength was very close to the analytical prediction made by Equation (1). The obtained \(V_{p}\) using the actual yield strength of SD400 rebar (430.2 MPa) was 102.6 kN, which is lower than the shear strength of the column section (175.3 kN). Thus, we could expect that flexural failure would occur. The lateral strength of the frame was expected as 102.6 \(\times\) 2 = 205.2 kN, which is very close to the actual maximum strength. \[V_{p}=\frac{2M_{p}}{h} \tag{1}\]  
where \(V_{p}\) represents the lateral strength of the frame at failure due to plastic hinge formulation at both ends of the columns, \(M_{p}\) is the plastic moment capacity of the section, and \(h\) is the column height. Compared to BF, the maximum forces of masonry-infilled frames were increased, but the deformation capacity was decreased. As expected, the maximum force was highest in IF-1.0 and lowest in IFS-0.5. Table 3 shows the maximum force and maximum displacement of each specimen and the strength ratio between the specimens with and without a gap. Specimens with gaps had a strength of 75% to 80% of specimens without gaps. In addition, the difference between the maximum force in the positive and negative directions was large compared with BF. This is likely due to residual strain in the masonry infills accumulated from low drift ratios. The specimens with double wythe masonry walls had lower deformation capacity than those of single wythe specimens. In other words, the higher the strength ratio of masonry compared to the frame, the lower the deformation capacity. This is consistent with the suggestion of ASCE 41 [25] for lower deformation capacity for the nonlinear modeling parameter of compression strut at a low value of \(\beta\), the strength ratio between the frame and the masonry infill (\(V_{fre}/V_{ine}\)). The specimen with a gap exhibited a lower deformation capacity than the specimen without a gap. This is thought to be due to the fact that the masonry in a specimen with a gap was not constrained, and thus fracture strain would be low. Effective stiffness can represent the load-displacement relationship of the specimen and is calculated using Equation (2). Table 4 shows the effective stiffness of all specimens calculated for each drift ratio. \[K=\frac{P_{u}^{+}-P_{u}^{-}}{D_{u}^{+}-D_{u}^{-}} \tag{2}\]  
where \(K\) is the effective stiffness; \(P_{u}\) and \(D_{u}\) indicate the peak force and displacement, respectively, for the considered drift ratio; and superscript (+) and (-) indicate the positive and negative directions, respectively. Tables 3 and 4 show that, compared to specimens without a gap, the specimens with a gap had 75% to 80% lower maximum strength and 55% to 70% lower effective stiffness. These results are comparable with those of a previous study by [PERSON] and [PERSON] [15], in which the initial stiffness decreased by 60% and the maximum yield strength decreased by 62%. The effective stiffness of IF-0.5 at a 0.1% drift ratio is very low compared with the stiffness of other specimens. This is most likely due to the slippage at the beginning of loading.