The Lightweight Steel Framing (LSF) system has been proposed as an economical system that is earthquake resistant. Due to the lightness of LSF structures, the seismic performance of middle-rise buildings has been improved. Nowadays, various numerical-analytical methods have been proposed for seismic assessment of conventional structures. Using scientific and statistical standards, this article provides two new methods for calculating the damage index of LSF structures. Once this index is determined, a correct understanding of structural behavior is obtained and the retrofitting criteria are drawn. The modified relationship method is based on Papadopoulos relationship which is modified using modification factors of seismic geotechnics. From another viewpoint, non-linear static analysis was used to calculate the criteria of this relationship. To detect the limit of the first failure and destruction of the entire structure, the formation of plastic hinges in columns is considered. Material properties were defined according to the performed experimental studies. 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 three LSF models there were made clear that the difference of the new method and the amended method of Papadopoulos is approximately 5%. This shows that the given qualitative method is suitable to be used in broad terms. Since the damage index of light steel structure for Model 1 and Model 3 are between 0.4 and 0.8, it is necessary to rehabilitate these structures using the modified method and the proposed qualitative damage index.
Mirzaaghabeik, H., & Vosoughifar, H. R. (2016). Comparison between quality and quantity seismic damage index for LSF systems. Engineering Science and Technology, an International Journal, 19(1), 497–510. https://doi.org/10.1016/j.jestch.2015.08.013