Research on residual drift response of steel frames under strong earthquakes

Steel frames designed to the current codes will undergo an unrecoverable plastic deformation under strong earthquakes. The structures subjected to excessive deformations after earthquakes cannot be desirably repaired to their serviceable state, and can only be demolished, which brings about a serious direct and indirect economic loss. Thus, it is of great significance to predict the residual drift for the performance evaluation and control of structures after earthquakes. In order to investigate the residual drift response of steel frames under strong earthquakes, steel frames between 2 and 10 stories in height are designed according to Code for seismic design of buildings (GB50011-2010) and Code for design of steel structures (GB50017-2003) in this study. The designed structures are investigated numerically by pushover analysis and elasto-plastic time history analysis. Furthermore, the peak drifts, residual drifts and drift concentration factors are reasonably obtained under the action of moderate earthquakes and major earthquakes. The results indicate that the scatter in the residual drift results is a bit large. On the basis of analysis results, the calculation formulae are proposed to estimate the residual drifts of steel frames as a function of the expected peak drift, the initial recoverable elastic drift, and the drift concentration factor of steel frames