For structures with normal importance in the earthquake resistant structure design of building bearing systems, the linear - inelastic behavior of the carrier system under the design earthquake is taken into consideration. Although it is different for each type of steel carrier system, the system is aimed to reach the most appropriate mechanism. Accordingly, linear-inelastic deformations are only allowed in certain elements. The structure is sized according to this behavior model.
In steel frames that transfer momentum, these elements are beams. The regions targeted for plasticization are certain regions at the ends of the beams connected to the columns.
These parts, which are named as the region of preserved capacity, absorb energy with linear - inelastic behavior, while the other parts must remain linear - elastic.
Columns should be stronger than beams in order not to be designed to cause brittle collapse, except for the intended mechanism .
In the above image (a) the holistic mechanism is the targeted system (b) the regional floor mechanism is not desired. As can be seen in (b), when the hinges are formed at the ends of the columns, this is a situation that causes brittle collapse.