Stories Drift Consideration in Steel Frames with Changing CBF Brace kinds in Height

Today's the most important purpose in structural designing is to control structural seismic demand against lateral forces in global surface and local surface. FEMA273 attributes the majority of deformation demands to behaviors surfaces whether there is no rule about local cumulative deformation demands of elements. On the other side cumulative deformation demands parameters have suggested criteria for damaging rate so it can exhibit a different vision of structures reflex about acquired reflex of maximum deformation demands. Comprehensive behavior of structures system depends on answer and manner of structural surfaces elements and influence of elements reflexes. Because of neglecting of scientist about brace changing in structures height so there is a consideration about steel structure seismic behavior with brace changing in height in the article. A number of moment steel frames braced by different bays, time history non-linear dynamic are analyzed by the 3 earthquake and consideration of max drift story demand in structures suitable height for chagrining the kind of braces was suggested. Changing the kind of braces in certain height of structures can reduce the structural local seismic demand.