Response to seismic sequences of short-period structures equipped with Buckling-Restrained Braces located on the lakebed zone of Mexico City

As part of an ongoing research program, this paper presents the results of a numerical study of steel frames with and without Buckling-Restrained Braces (BRBs), representative of essential buildings (e.g. hospitals). The aim of this study is to understand the effects of seismic sequences on this type of structures when located on the soft soil of Mexico City. For that purpose, three-, six-, and nine-storey frames were designed under diverse criteria and analysed under artificial sequences to understand the influence of BRBs on the peak and residual inter-storey drifts demands. The results showed that the effect of aftershocks is very significant when their intensity, in terms of peak-ground velocity, is similar to that of the mainshock. It is also shown that, although aftershock effects may not be eliminated, a proper design based on the concept of dual systems could help to mitigate aftershock effects. Based on the analytical results, expressions to estimate the magnitude of peak and residual inter-storey drift demands under mainshocks and the sequence mainshock-aftershock are offered as a helpful guide to structural designers.