NUMERICAL SIMULATION OF THE INELASTIC SEISMIC RESPONSE OF RC STRUCTURES WITH ENERGY DISSIPATORS

P. MATA; A. BARBAT; S. OLLER; R. BOROSCHEK

Conferencia; 14th World Conference on Earthquake Engineering; 2008

Conventional seismic design practice permits designing RC structures for forces lower than elastic ones, on the premise that the design assures significant ductility. Frequently, the dissipative zones are located near the beamcolumn joints and, due to cyclic inelastic incursions, structural elements can suffer a great amount of damage.New techniques based on adding devices with the objective of dissipating the energy exerted by the earthquake and alleviating the ductility demand on primary structural elements have contributed to improve the seismic behavior of buildings. In the case of passive energy dissipating devices (EDD) an important part of the energy input is absorbed and dissipated, therefore, concentrating the nonlinear phenomenon without the need of anexternal energy supply.Most of he design methods proposed for RC structures are based on the assumption that the behavior of the bare structure remains elastic, while the energy dissipation relies on the control system. However, experimental and theoretical evidence show that inelastic behavior can also occur in the structural elements of controlled building during severe earthquakes. Considering that most of the elements in RC buildings are columns andbeams, one-dimensional formulations for structural elements appear as a solution combining both numerical precision and reasonable computational costs. Some formulations of this type have been extended for considering geometric nonlinearities and considering inhomogeneous distributions of materials on arbitrarily shaped beam cross sections.Formulations for beams considering both constitutive and geometric nonlinearity are rather scarce; most of the geometrically nonlinear models are limited to the elastic case and the inelastic behavior has been mainly restricted to plasticity. Recently, Mata et.al.have extended the geometrically exact formulation for beams due to Reissner and Simo to an arbitrary distribution of composite materials on the cross sections for the static and dynamic cases. EDDs usually have been described in a global sense by means of force-displacement or moment-curvature relationships attempting to capture the energy dissipating capacity of the devices.