NUMERICAL TOOL FOR NONLINEAR SEISMIC ANALYSIS OF BUILDINGS WITH ENERGY DISSIPATING SYSTEMS

P. MATA; S. OLLER; A. BARBAT

Seminario; 9th World Seminar on Seismic Isolation, Energy Dissipation and Active Vibration Control of Structures; 2005

The nonlinear dynamic response of civil structures with energy dissipating devices is studied. The structure is modeled using the Vu Quoc?Simo formulation for beams androds, which allow to consider the changes in the configuration of the structure during the analysis. The effects of shear stresses are considered, allowing to rotate the local system of each beam independently of the position of the beam axis. The material nolinearity is treated at material point level with appropriated constitutive laws, employing a simple Kachanov?s model for degrading materials and a elastoplastic material with fiber behavior for steel reinforcements and stirrups. The simple mixing theory is used to treat the composite. The equation of motion of the system as well as the conservation laws are expressed in terms of sectional forces and generalized strains and the dynamic problem is solved in the finite element framework. A specific kind of finite element is proposed for modeling the energy dissipating devices. This element is constructed on the base of simple rods with only one Gauss integration point. Specific one dimensional constitutive laws have to be given for each kind of dissipative mechanism of the device.