Advantages, Steel buildings are %50 lighter than reinforced concrete buildings. Therefore steel structures are less affected by earthquake load. Since steel is a ductile material, the earthquake energy is absorbed by creating plastic deformation at connection joints, therefore steel structures are less affected by earthquake. Since the factory fabrication conditions & quality control are favorable than site production conditions; achieving the predicted quality at design step is easier by using steel structures. When it is necessary, it is possible to disassemble the existing profiles and use at another steel building. Therefore steel buildings are always more economical than concrete buildings. It is easy to check the material quality at steel structures. If additional loads affect the building after the project is completed, it is easily possible to strengthen the steel building by welding additional steel plates to the existing structural system. But the same system is more costly and time consuming at concrete buildings. The steel profiles damaged by any reason can be replaced by new profiles easily. Since the steel can be produced in various forms, it is easy to implement the architectural projects. All electrical and mechanical equipment can be passed through the space between beams and suspended ceiling. So there is no need to make holes at load bearing system. Large spans which are not possible to construct by reinforced concrete system, can be constructed by steel structure system. Since steel is a homogeneous and isotropic material, behaves as expected in statical calculations. Disadvantages, The disadvantage of using steel can be assumed as protection against the corrosion and fire. But it is easy to solve this problem by using anti-corrosive and fire resistant coatings.