Proper perception of structural behavior of a connection and enough knowledge of the way it transfers forces, is an integral part in designing a safe connection. Since the dysfunction of the connections, causes lots of destructions, therefore precise investigation of the function of these connections in steel structures is very important. Because inaccuracy in designing and executing connections, in addition to demolition of that connection, it will have irreparable damages on members and the whole structure too. 
What should be considered in parallel with using H.S.S as column in steel frame structures, is the design of beam connections to this type of column. During previous years, numerous methods for various types of beam to column connections have been proposed in different countries.
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