Shift of natural frecuencies in buildings damaged by earthquakes

Earthquakes could produce important damages in buildings, representing an important impact on the economy of many countries. The damaging is particularly severe when the dominant frequency of the quake approaches one of the resonant frequencies of the building. One typical failure occurs through the weaking of some beam-column joints, generally along with the presence of cracking. The standard procedure for repairing this, is by reinforcing the damaged zone with steel plates sleeves or by mean of a new section of reinforced concrete covering the old one. These arrangements change the mechanical stiffness and the mass of the structure itself. Accordingly, this work aims to study those mass and shiftness change of the structure through a non-linear optimization of the modal analysis of the building, which enables to analyze the potential shifts in natural frequencies of the structure and thus propose the best conditions under which a damaged building could be repaired efficiently.