evaluation of the methods estimating structural strength reduction factor under far field records

The structural strength reduction factor is defined as the minimum ratio of lateral resistance of structure with a completely elastic behavior to that of the same structure with nonlinear behavior, for a given displacement ductility ratio. it is influenced by the imposed demand of earthquake on the structure and has a decisive impact on achieving performance objectives. the more precise estimation of mentioned demand, the more economical the design would be.it is worth mentioning that, in different performance-based methods, such as energy-based and equivalent linearization design, the strength reduction factor directly or indirectly plays a key role. over the past four decades, extensive research has been conducted to estimate the strength reduction factor, which indicates the importance of this estimation in structural design. newmark and hull (1973, 1982), riddle and newmark (1979), lai and biggs (1980), riddle hidalgoand cruz (1991), hidalgo and arias (1990), osteraas and krawinkler (1990), nassar and krawinkler (1990), vidic et al.(1994), miranda (1993), miranda and bertero (1994, 1991), ordaz and perez-rocha (1998), lee et al. (1999), espinosa and gilmore (2002), ruiz-garcia miranda (2003), chopra (2004), zhai (2006), hatzigeorgiou (2010), asce41 (2017).