In the recent severe earthquakes, it has been observed that the existed buildings are damaged so much. The important point is that even modern buildings are damaged very much. So that the damages cause high structural breakage and in some cases it causes total destruction. So to reach to a suitable strategy to decrease earthquake risks in urban areas, prediction of vulnerability of buildings resulted from possible earthquakes in future is one of the most necessary duties of structural engineering. As we know damages occur in plastic area, so vulnerability analyzing must be done in the area. Among this, modeling of reinforced concrete is an important step to determine earthquake damages. Structural models must be able to model reinforced concrete elements and provide correct analyzing of their nonlinear function. Hysteric behavior of concrete due to conversional forces is also necessary for a suitable structural model. Usually a certain structure must perform several functional levels. So a method is required to determine requirement of entering into structure under probable earthquakes.