Luco, J. Enrique

Influence of Viscous Damping Models on Inelastic Seismic Response of Fixed and Base-Isolated Structures

Abstract eng:
Work conducted over the last 30 years by a number of authors indicate that the details of the inherent damping model have a significant effect on the calculated inelastic structural response and, particularly, on the calculated damping forces. In some cases, unrealistically large damping forces can be obtained, which may imply unconservative results. Also, it is known that the mass-proportional term in the Rayleigh and Caughey damping matrices may be responsible for large damping forces for base-isolated or poorly constrained structures. In the absence of sufficient experimental data, there is a lack of consensus on the most appropriate model for inherent damping. The first objective of the paper is to present and evaluate a new damping model in which the inherent damping force during inelastic vibrations is taken to be proportional to an estimate of the elastic component of velocity rather than to the total velocity which includes plastic and elastic components. This model has a number of theoretical and computational advantages. The second objective is to investigate the effect that different damping models, including models based on: (i) initial structural properties, (ii) degraded properties (tangent stiffness), and (iii) the new ‘elastic’ velocity model, have on the seismic response of fixed and base-isolated structures. In each case, three different estimates of the damping matrix are considered: (1) Rayleigh damping, (2) optimized Caughey series including and excluding the mass proportional term, and (3) modal damping matrix. The effects of different viscous damping models are quantified by numerical inelastic timehistory analyses of a multi-story structure subjected to different earthquake excitations. The final objective is to study numerically whether a harmonic critical excitation exists for a multi-story structure supported on a bilinear hysteretic isolator system. This would extend previous analytical findings for a simple bilinear oscillator and for a 1-DOF structure resting on a bilinear hysteretic isolator, that even in the presence of hysteretic damping, a critical amplitude of the harmonic excitation exists, beyond which the resonant response of the structure can be unbounded (in absence of viscous damping) or very large (in presence of isolator damping).

Contributors:

Lanzi, Armando

Conference Title:

Proceedings of the 16th World Conference on Earthquake Engineering

Conference Title:

16th World Conference on Earthquake Engineering

Conference Venue:

Santiago (CL)

Conference Dates:

2017-01-09 / 2017-01-13

Rights:

Text je chráněný podle autorského zákona č. 121/2000 Sb.