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Since beam-column connection plays a prominent role in steel structures, by designing and constructing it properly, the structure will behave better and safer. Numerous researches are carried out on steel connections, like Reduced Beam Section (RBS) and Drilled Flange Connection (DFC). Each connection has advantages and disadvantages. This study evaluates the effect of different connections on behavior of steel moment frames. The connections evaluated in this study are as follows: Connection with drilled attachment part, drilled connection with identical and variable diameter, beam connection with reduced flange. This connection contains one or two replaceable drilled parts that are mounted in connection place. The connection is modeled using the ABAQUS software. Finally, Finite Elements Modeling (FEM) is utilized to calculate the stiffness of each connection. According to the results of the newly introduced connection in terms of energy absorption and ductility is the best example and among the drilled models investigated in this study, drilled connection with variable diameter (proportional to diamond shape) which performed better in terms of behavior and performance than the other perforated models. Also, reduced flange connection ranks third in performance. In proposed connection the plastic hinge is formed at the attachment part of the connection that is replaceable, also there is little damage to the beams and columns, which is one of the main benefits of this connection.

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the purpose of this project was to introduce a way to improve the mechanical properties of welded dissimilar material, which gives benefits such as affordable, high speed, and suitable bond property. In this experimental project, the friction welding method has been applied, including combining parameters, such as numerical control (NC) machine including two different speeds, and three different cross-sections; including flat, cone, and step surfaces. When the welding process was done, samples were implemented and prepared via bending test of materials. the results have shown that, besides increasing the machining velocity, the surface friction increased, and so did the temperature. By considering the stated experimental facts, the melting temperature of composite materials has increased. This provides the possibility of having a better blend of nanomaterial compared to the base melted plastics. Thus, the result showed that, besides increasing the weight percentage (wt %) of Nanomaterials contents and machining velocity, the mechanical properties have increased on the welded area for all three types of samples. This enhancement is due to the better melting process on the welded area with attendance of various Nanoparticles contents. Also, the results showed that the shape of the welding area could play a significant role, and the results also change drastically where the shape changes. Optimum shape in the welding process has been dedicated to the step surface. The temperature causes the melting process, which is a significant factor in the friction welding process.