Abstract | An improvement of the Italian Code bilinear fit for static pushover (SPO) curves is put forward aimed at significantly decreasing the error introduced in the conventional SPO analysis by the piecewise linear fitting of the capacity curve. While other issues, such as the relationship to pass from the response of multi-degree-of-freedom to single-degree-of-freedom systems (MDOF – SDOF), have been heavily examined in the last decades and improvements and changes to the original method have been proposed and introduced in codes and guidelines, the piecewise linear fit assumed has not yet been systematically investigated. The determination of an optimal multilinear fit has now become a more pressing issue, since new generation modeling approaches lead to highly curved pushover shapes with significant stiffness changes, especially when explicitly incorporating the initial uncracked stiffness of sections. In such cases, even determining the code-standard equivalent elastic stiffness and yield strength of the simple elastic-plastic approximation can be greatly improved upon. In the approach proposed herein, the error introduced by the piecewise multilinear fit of the force-deformation relationship is quantified by studying it at the SDOF level, away from any interference from MDOF effects. Incremental Dynamic Analysis (IDA) is employed to enable a direct comparison of the actual curved backbones versus their piecewise linear approximations in terms of the spectral acceleration capacity for a continuum of limitstates, allowing an accurate interpretation of the results in terms of performance. An optimized elastic-plastic bilinear fit is the first enhanced solution to decrease systematically the error introduced in the SPO analysis if