## 6 Conclusions  
In this study on the seismic behavior of welded plate connections in the flanges and web, in concrete-filled tubular columns, four types of connections were evaluated under cyclic loading, using the finite element method. The results revealed that none of the connections meet the flexural strength criterion at 0.04 rad. Still, all exceeded 80% of the plastic moment at 0.02 rad, valid for an intermediate frame (IMF) type building in areas of moderate seismicity. Connection 1-A reached a maximum plastic moment of 98.39% at 0.02 rad, and 85.98% at 0.04 rad, respectively; with a plastic deformation of 20% and a maximum Von Mises stress of 516.12 MPa at 0.04 rad. Connection 2-A reached a maximum plastic moment of 95.94% at 0.02 rad, and 86.39% at 0.04 rad, respectively; with a plastic deformation of 12% and a maximum stress of 432.57 MPa at 0.04 rad. Connection 2-B reached a maximum plastic moment of 100.01% at 0.02 rad and 90.91% at 0.04 rad, respectively; with a plastic deformation of 14% and a maximum stress of 455.90 MPa at 0.04 rad. Finally, connection 3-A reached a maximum plastic moment of 100.86% at 0.02 rad, and 90.15% at 0.04 rad,  
Figure 14: Equivalent plastic strain: (**a**) connection _1-A;_ (**b**) connection _2-A;_ (**c**) connection _2-B;_ (**d**) connection _3-A._  
respectively; with a plastic deformation of 15% and a maximum stress of 463.28 MPa at 0.04 rad. The increase in SMF systems motivates the use of new connections that are not approved according to current design regulations. Therefore, it is necessary to research to ensure that the frames are designed to absorb seismic energy in the beams without affecting the connections. Under this context, this work presents a numerical model and an analysis of the inelastic behavior under cyclic loads of a steel beam - rectangular steel tubular column connection, filled with concrete, using plates. New research could be aimed at increasing the portfolio of connecting steel beams to rectangular tubular columns, also made of steel, filled with concrete, using external diaphragms and analyzing different configurations, that is, column sections, beam profiles and types of concrete suitable for earthquake-resistant applications. In some works, the validation of new connections has already been reported, such as that of a steel beam to a tubular steel column filled with concrete using external diaphragms, leading to the definition of the finite element analysis methodology, corroborated by an experimental protocol. Therefore, the methodology applied in this computational study compiles all the estimates used in real cases and taken to a virtual environment [34]. Future research could also study the pinching effect in screw connections in more detail. Additionally, diaphragms could be connected to the column wall using full penetration welds with 45-degree angles. It would be worth considering whether full penetration and partial penetration welds can be combined to reduce manufacturing time and costs, despite the increase in computational cost. In the design process of the building alternatives, with tubular profiles with and without concrete filling, the demand capacity of the structures and the floor drifts was guaranteed to comply with the NEC-SE-DS [24] standard and the specifications of the AISC-360 [4] standard. Priority was given to optimizing the structural elements, both columns and beams, which allow operating with smaller sections than those used in the frame design with type I laminated profiles. Thus, an efficient structure with less weight in its structural elements is established. The strong column-weak beam criterion prevented the columns from entering the inelastic range and prevented plastic hinges from developing in the beams, thus preventing energy dissipation. The columns filled with concrete turned out to be the most effective, since the moment ratio reached the highest values compared to the other models.