Non-linear Correlation Coefficients for pushover analysis

Aiming to put forward an improvement on Multimodal Pushover Analysis, a modified version of the modal correlation rule that takes into account the non-linear behavior of structures is proposed. The modification is primarily based on using the correlation coefficients consistent with the mechanical and dynamical properties of the hysteretic oscillators utilized in the MPA method, i.e. determined taking into account the second order statistics pertinent to the non-linear oscillators. Initially, the new correlation coefficients are evaluated by Monte Carlo Simulations (MCS), assuming a spectrum-compatible representation of the seismic input. The results of a large numerical parametric analysis are shown. Moreover, analytical expressions for the proposed correlation coefficients are derived on the basis of the stochastic linearization technique. Lastly, the results provided by the modified MPA for a simple 2DOF system are compared with Non-linear Response History Analysis