Seismic analysis of older and contemporary reinforced concrete frames with the improved fish-bone model

Abstract

The improved fish-bone (IFB) model for seismic analysis of older and contemporary reinforced concrete frames is proposed by introducing a new procedure for the estimation of parameters of structural elements of the fish-bone model. The procedure makes it possible to approximately account for the importance of structural elements on the seismic response of a frame building and the effect of potential redistribution of demands between structural elements of the frame building. Firstly, the IFB model is described. Follows demonstration of its capability by simulating the response history of storey shears, storey drifts and storey accelerations of selected pseudo-dynamically tested frames. Finally, it is shown that the IFB models can provide pushover curves, the corresponding damage states and fragility functions based on response history analysis which are very similar to those obtained by the conventional multi-degree-of-freedom models. The capability of the IFB model with respect to conventional fish-bone model is also demonstrated by the pushover analysis. It can be observed that the IFB model significantly improves the simulation of the older reinforced concrete frames, which do not fulfil the strong column – weak beam concept, and the frames for which the columns or beams of one storey of a frame building differ significantly from each other. Additional research is needed to extend the capabilities of simplified structural models to plan irregular frame building.