Ductility, or deformation energy, is by far the largest source of energy dissipation of structures, since normal levels of internal damping represent only a small portion of energy dissipation. However, large material deformations such as those required in building components to perform in a ductile manner, are often associated with cracking and degradation of its strength, particularly in concrete structures. The installation of some manufactured devices to critical regions of structural systems, specifically engineered to concentrate on them the largest part of the dissipated energy during an earthquake, increases the structure's overall thoroughness and improves its performance and reliability during major seismic events.
This paper describes the retrofit of three buildings in Mexico City using damping devices. The size and number of these added elements are a function of the dynamic characteristics of the specific structure, the amount of previous damage, the anticipated earthquake motion imposed to the structure and the design performance level intended.