Seismic Target-Displacement of Multistorey Reinforced Concrete (R/C) Frames Using Pushover Analysis and Inelastic Spectra

Abstract

A methodology for the evaluation of the seismic target-displacement of multistory reinforced concrete (r/c) frames in earthquake civil engineering is presented. As well known, such methodologies based on the pushover analysis and  proposed in the literature are not fully documented yet.  In the present paper, a methodology based on the optimum definition of equivalent non-linear single-degree-of-freedom (SDF) system and combining the static pushover procedure and the inelastic spectra analysis is first presented .Next, the methodology is applied to the actual  case of an existed 3-span, two-storey r/c frame,  designed by the old Hellenic Seismic Code (AK/1959). The proposed methodology comprises the following main steps: (a) Analyses of critical sections of all structural elements in order to calculate the bilinear diagram of moment-curvatures (M-c) and the diagram of moment-axial forces (M-N), (b) transformations of bilinear diagram M-c in bilinear diagram M-θ(moments-rotations) using a suitable length of each plastic hinge, (c) the gravity loads of the system are in action, (d) the static pushover analysis is performed using the force distribution of the 1st mode shape of the system, (e) Calculation of the bilinear diagram of the pushover curve of the system, (f) Calculation of the seismic target-displacement using the optimum equivalent non-linear SDF system with the inelastic response  spectra, (g) Calculation of the seismic demand floor displacement of the system.
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