One of the most devastating earthquakes in the
history of Mexico was the earthquake of 1985. The seismic design code of Mexico
City was urgently revised just after this earthquake. Furthermore, it was
modified in 1987 and 2004, incorporating the earthquake damage analysis results
and the latest knowledge on earthquake engineering.
In 2017, the
Puebla Earthquake occurred and struck Mexico City. About twenty buildings
collapsed, and more than 200 peoples died due to this earthquake. The survey
results have found out that most of the buildings that collapsed in this
earthquake were designed based on the old seismic code before 1985. Therefore,
seismic performance evaluation and retrofit of these old buildings is still one
of the significant issues.
In this study, the author investigated
the ADAS's potential as dampers to retrofit existing reinforced concrete
buildings. The ADAS, which means the "Added Damping and Stiffness,"
is one type of steel hysteretic dampers. This ADAS damper yields in bending during
an earthquake and dissipates seismic energy by its plastic deformation. The
original developer devised its shape so that plastic deformation occurs in a
broader area without stress concentrating on a specific part.
The author took up one existing public
office building and attempted to retrofit it using this ADAS. He carried out
earthquake response history analyses and compared the building's dynamic
behaviors before and after retrofitting. The results cleared that we could
reduce inter-story drift angles by inserting the ADAS in the building.
Finally, the
author considered a possibility of the damper's fatigue failure due to
long-term
earthquake ground motions.
Keywords: Seismic retrofit, Hysteretic steel damper,
Inter-story drift angle, floor response acceleration, fatigue failure.