Nonlinear response estimates of RC frames using linear analysis of SDOF systems

Abstract

SUMMARY An approximate‐simple method for nonlinear response estimates of reinforced concrete frames subjected to near‐field and far‐field records is presented in this paper. The approximate method is based on equivalent single‐degree‐of‐freedom and linear multi‐degree‐of‐freedom models. In this procedure, the nonlinear maximum roof displacement is estimated using an effective period factor and elastic response spectrum with an equivalent damping. The effective period factor was proposed for far‐field and near‐field ground motion records. For regions of high seismicity, the maximum roof displacement can be estimated by applying an effective period factor of 2.3 and 2.1 for near‐field and far‐field records, respectively, and 9% damped displacement response spectrum. For regions of moderate seismicity, a lower effective period factor of 1.9 and 1.8, for near‐field and far‐field records, respectively, can be applied to estimate the maximum roof displacement. A relationship between linear and nonlinear response of multi‐degree‐of‐freedom systems was also proposed to obtain estimates of the maximum inter‐story drift of nonlinear responding reinforced concrete frames. In addition, the effects of number of ground motion records used in the analyses on the scatters of results were investigated. The required number of ground motions to produce a reliable response was proposed. Copyright © 2013 John Wiley & Sons, Ltd.

Evaluation of the structural damage of high‐rise reinforced concrete buildings using ambient vibrations recorded before and after damage

“…In this regression equation, the natural frequency ratios for Building I, which resulted from the 2004 Southeast off the Kii Peninsula Earthquake (M w 7.4) (Figure 2), its foreshock (M w 7.3), and its aftershock (Mw 6.9), in addition to those of the two major earthquakes, were also taken into consideration. The effects of input ground motion waveform and duration on the stiffness degradation rate are small [4], and the observed values for both earthquakes conform well to the regression equation. This is consistent with previous findings showing that the stiffness degradation rate of RC buildings is controlled by the PIDR.…”

Simplified procedure for the estimation of local inelastic deformation demands for seismic performance assessment of buildings

“…In fact, the increase in T 1 of building SB3 due to the reduction of stiffness of the members proposed by Günay and Sucuoglu , changed λ from 0.85 to 1.0 and consequently resulted in higher structural demands. Better estimates could be obtained by using an elastic response spectrum with an equivalent damping as proposed by Yaghmaei‐Sabegh et al . Moreover, a good match between the linear elastic chord rotations obtained using MRSA and the mean ‘true’ nonlinear chord rotations was obtained for buildings SB1 to SB3 (e.g.…”

“…Likewise, Browing et al developed a simple relationship that allows for the estimation of nonlinear maximum roof displacements using an effective period factor and elastic response spectrum with an equivalent damping. This procedure has been recently improved by Yaghmaei‐Sabegh et al to account for the influence of both far‐field and near‐field ground motions and to provide estimates of the maximum inter‐storey drift of RC frames. Additional works that focused on the assessment and development of methods to estimate the inelastic demands from linear methods of analysis may be found in the literature .…”

Estimation of inelastic displacement ratio for base‐isolated structures

“…They include displacement coefficient method (DCM), capacity spectrum method, modal pushover analysis, and N2 method . Moreover, equivalent linearization methods are available as reported in Yaghmaei‐Sabegh . In particular, DCM framework estimates the inelastic displacement of structures (target displacement) by applying a succession of coefficients upon the elastic spectral response of corresponding linear single degree of freedom (SDOF) system in its fundamental vibration mode.…”

“…7 Moreover, equivalent linearization methods are available as reported in Yaghmaei-Sabegh. 8 In particular, DCM framework estimates the inelastic displacement of structures (target displacement) by applying a succession of coefficients upon the elastic spectral response of corresponding linear single degree of freedom (SDOF) system in its fundamental vibration mode. A key factor in the estimation of target displacement is inelastic displacement ratio (designated as coefficient C 1 in American documents [1][2][3][4][5] ).…”