Martin, Juan Carlos De La Llera

Implementation of Elastomeric Seismic Isolation in Tall Buildings Considering Axial-Lateral Coupling in the Isolators

Abstract eng:
Seismic isolation of high-rise buildings presents an opportunity but also a challenge to seismic isolation, a technique mostly used in the past in low and moderate-rise buildings. It turns out that under certain conditions of the structure and input, it is perfectly reasonable to protect tall structures using seismic isolation. The objective of this research is to explore these conditions in simple structural models. A parametric analysis on seismically isolated tall buildings was performed using first a simplified representation of the superstructure as a 3D rigid rectangular prism, geometrically characterized by its height and aspect ratio in plan and height. The elastic properties of the isolation system were lumped at the isolation interface by assuming circular elastomeric devices connected to the nodes of a regular grid at the base. The energy dissipation of the isolation devices was incorporated by assigning a constant damping ratio to the six degrees of freedom of the model. The results of this linear elastic model help identify problems of rocking at the base and tensile loads on the isolators in some cases. The results obtained from the rigid body model for the building were extended to a second parametric model that considers finite stiffness on the superstructure. For the sake of simplicity, 2D non-linear analyses were performed with focus on the isolator tensile loads and the building inter-story drifts. Two building models were considered, a simple frame with three column axes, and a mixed frame with a central wall. The Koh & Kelly non-linear two-spring model was used to characterize the isolators. The results of this analysis show that it is possible to implement seismic isolation in buildings with height-to-base aspect ratio of up to 6:1 without excessive tensile loads on the isolators if theoretical isolation periods go over 6s. Additionally, in these tall and slender buildings, the inter-story displacement reductions decrease with aspect ratio. Also, base shear and floor accelerations are reduced in tall and slender buildings, but the reduction is less significant than the reduction obtained for the relative lateral displacement and drifts.

Contributors:

Maureira, Nelson

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:

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