## 3 Results and Discussion  
### Hysteresis Curves  
Figure 7 shows the moment-angle plot obtained by the test specimen. The hysteresis curves can also be observed in the figure. This plot allowed us to verify that the connection provides the necessary requirements to be qualified. To perform the verification, the limit that must be exceeded for its approval in special energy dissipation systems was drawn in the plot. Four horizontal lines are shown at the top and bottom of the graph. The description of these lines is as follows: the green line represents the minimum flexural capacity \(\pm 0.8\)\(M_{\text{P}}\); the dark red line represents the plastic moment \(\pm M_{\text{P}}\); the black line represents the maximum probable moment \(\pm M_{\text{P}}\); the line in red on the abscissa at \(\pm 0.04\) rad is the limit required for approval of the specimen. Figure 6: Displacement protocol. The abscissa is presented in units of time in s, obtained as the quotient between the displacement \(\Delta\) and the loading application speed \(v\). In this case \(v=1.49\) mm/s. Figure 7: Hysteretic curve (moment–angle). Since the general behavior of the specimen before reaching the displacement of 0.04 rad did not show degradation in its resistance in terms of the load applied to the actuator, the protocol was continued to the maximum value allowed by the frame, which was up to a rotation of 0.07 rad. This value was reached with 0.01 rad increments every two cycles. The pinching effect can also be observed in the hysteresis curve of Figure 7. This effect is a very important characteristic within the evaluation of the power dissipation capacity of a connection. In general, such effect can occur by three main factors: concrete cracks, bolt slip and the sequence of the yield and strength hardening. According to [PERSON] and [PERSON] [16], concrete cracks once its tensile strength is overcome, and this effect added to the bolt slip and the sequence of the yield and strength hardening cause a decrease in stiffness that can be observed as the pinching effect in the hysteresis curve. The influence of the three factors causing pinching in the hysteresis curve of this work (Figure 7) is discussed next. Regarding the effect of the concrete cracks on pinching, the confinement and support provided by the walls of the tubular column contribute to the avoidance of failures because, for this type of connection, the action of the compression forces causes the cracks to close gradually, which contributes to the recovery of the rigidity of the concrete core. Crack nucleation in the concrete core was verified to identify its contribution to the pinching effect. For this, the core of the column was removed, and it was verified that the concrete did not present any cracks. Thus, regarding the column, it was determined that the specimen did not present an incursion into the inelastic range. Regarding the pinching due to the bolt slip and the sequence of the yield and strength hardening, it occurs when a load overcomes the frictional force exerted by the pretensioning of the bolts that holds said plates together. The smaller diameter of the bolt, the smaller the tension required by the standard, which leads to a lower total force required to overcome the friction component. Additionally, the curve shows slope changes that allow us to identify the displacement between plates due to the clearance between the nominal diameter of the bolt and the diameter of the diaphragm holes. It is worth mentioning that the slippage effect does not prevent the connection from being utilized in SMFs with special energy dissipation capacities. The slippage effect is well known and has been documented for the qualification process of the bolted flange plate (BFP) moment connection covered by AASC 358-16 [4]. Regarding rotation, before a rotation angle of 0.04 rad, the flexural strength of the connection measured to the face of the column was 402.07 kNm.