A Novel Procedure for the Assessment of the Seismic Performance of Frame Structures by Means of Limit Analysis

TL;DR

This paper introduces a new method using limit analysis to evaluate the seismic performance of frame structures by reconstructing capacity curves and defining an equivalent SDOF system, validated for accuracy and efficiency.

Contribution

The authors develop a novel approach that extends limit analysis to assess displacement capacity and seismic performance, overcoming traditional limitations.

Findings

The method accurately predicts seismic performance compared to nonlinear static analyses.

It is computationally efficient and suitable for practical engineering applications.

The approach effectively incorporates second order effects and post-peak softening in capacity curves.

Abstract

Limit analysis is a computationally efficient tool to assess the resistance and the failure mode of structures but does not provide any information on the displacement capacity, which is one of the concepts which most affects the seismic safety. Therefore, since many researchers did not consider limit analysis as a possible tool for the seismic assessment of structures, its widespread employment has been prevented. In this paper this common belief is questioned and the authors show that limit analysis can be useful in the evaluation of the seismic performance of frame structures. In particular, to overcome the limitation on the possibility to evaluate the displacements of a structure based on a limit analysis approach, an approximated capacity curve is reconstructed. The latter is based on a limit analysis strategy, which takes into account the second order effects, and evaluates the displacement capacity considering a post-peak softening branch and a threshold on the allowed plastic rotations. Then, based on this simplified capacity curve, an equivalent single degree of freedom system is defined in order to assess the seismic performance of frame structures. The proposed simplified strategy is implemented in a dedicated software and the obtained results are validated with well-established approaches based on nonlinear static analyses, showing the reliability and the computational efficiency of this methodology