Buckling-restrained braces are commonly installed in building structures as concentric diagonal or chevron
braces to protect the main construction from seismic actions. These elements have shown repeatedly their usefulness for
reducing the seismic response, both from theoretical and experimental studies; and a number of practical applications have
been reported. However, seismic records with near-fault effects possess special characteristics that might impair the performance
of these devices, similarly as what occurs in base isolation; about energy issues, in such records (containing
strong velocity pulses) the energy is delivered in a short time interval, thus being difficult to be absorbed. This work presents
a numerical study regarding the performance of buckling-restrained braces under three types of seismic records: cortical
far-field, subductive far-field and near-field (i.e. containing velocity pulses). The study is carried out on a symmetric
4-story steel moment-resisting unbraced frame that was tested at the E-defense laboratory, Japan; the dynamic response of
such unbraced bare frame is numerically simulated, obtaining a satisfactory agreement. The same numerical model is used
to describe the 2-D dynamic behavior of the steel frame equipped with buckling-restrained braces. The inputs are three series
of ten ground motion records; each of these series belongs to one of the three aforementioned types. The average responses
for each of the three types of inputs are compared; the obtained results show that the buckling-restrained braces
are able to reduce the dynamic response of the frame and that no significant differences can be observed among the efficiency
for far-fault and near- fault records.
Prof. Comparing H2 and H∞ Algorithms for Optimum Design of Tuned Mass Dampers under Near-Fault and Far-Fault Earthquake Motions
