Seismic design and retrofit of structures using dissipative devices.

A. BARBAT; S. OLLER; P. MATA; X. MARTINEZ

Guidelines for seismic vulnerability reduction in the urban environment: LESSLOSS

IUSS Press

Año: 2007; p. 139 - 206

Conventional seismic design practice permits designing precast and cast in place reinforced concrete (PRC and RC, respectively) structures for forces lower than those expected from the elastic response on the premise that the structural design assures significant energy dissipation potential and, therefore, the survival of the building when subjected to severe earthquakes. Normally, energy dissipation during seismic actions occurs in critical zones of the structure specially designed to admit large ductility demands. Frequently, these zones are located near the beam-column joints and during earthquakes, several structural members can suffer a great amount of damage with irreversible degradation of the mechanical properties of the materials. Even if a limited level of structural damage dissipates part of the energy offering certain level of protection against seismic actions (Mata et.al. 2006, Lessloss Deliverable report 54, 2005 (www.lessloss.org)), the large displacements required for developing hysteretic cycles in dissipative zones can cause severe damage in those members, but this situation is generally considered economically acceptable if life safety and collapse prevention are achieved. In the last decades, new concepts for the design of building, based on the manipulation of the energy dissipation, have improved the seismic behaviour of the RC and PRC structures providing higher levels of safety for the occupants, buildings and nonstructural components. The new techniques are based on adding devices to the buildings with the main objective of dissipating the energy demand imposed by the earthquake alleviating the ductility demand on primary structural elements and decreasing the acceleration response (Soon and Dargush, 1997; Handson et.al. 1993).  The purpose is to control the seismic response of the buildings by means of a set of dissipating devices which constitutes the control system, adequately located in the structure.