Hossein Mirza Aghabeik - M.S student of Structure, Department of Civil Engineering, Islamic Azad University, South Tehran Branch,Iran
Hamid Reza Vosughifar - Associated professor, Department of Civil Engineering, Islamic Azad University, South Tehran Branch, Iran

The Lightweight Steel Framing (LSF) system has been proposed as an economical system and earthquake resistant. By identifying the damage index of a structure, in addition to a correct understanding from real behavior of the structure, the required criterion for strengthening would be given. In this paper two new methods are given for calculation of damage index. Surveying the first crack limit and total structure failure is based upon the formation of plastic joints in the first column and basic floor columns. To give a qualitative simple and functional damage index, the functional method was given in the form of a qualitative method with statistical analysis and collection of different views. Using this method is very simple and meantime offers suitable accuracy. With a numerical study on one three dimensional Light Steel Frame model it was made clear that the difference of new method with amended method of Papadolos in approximate 1.38% This shows that given qualitative method is suitable to be used in a broad terms.

Light Steel Frame; Quality Damage Index; Earthquake; Reformed Method