Dynamic analysis on structures base-isolated by a ball system with restoring property

Abstract

SUMMARYA computational model with its analysis method for base-isolated structures by a ball system with restoring property under seismic force is proposed in this paper, and the programs using numerical integration method and incremental harmonic balance method are developed. The analysis method is verified by shaking table test results of a three-storey masonry model. With these programs, the effect of some factors on the aseismic behaviour of base isolation system are analysed, and the comparison of seismic response between structures with and without base isolation is made. Results of both theory and test show that the above-mentioned base isolation system has apparent advantages over the traditional aseismic structures.

Sloped multi‐roller isolation devices for seismic protection of equipment and facilities

“…The currently available passive isolation bearings can be classified into three primary types: (1) elastomeric [4,5]; (2) sliding-based [6,7]; and (3) rolling-based [8][9][10][11][12][13][14][15][16]. Similar to successful applications of seismic isolation technologies to building and bridge structures [17][18][19][20], the implementation of seismic isolation devices, instead of conventional restraints [21], to equipment or facilities may be one of the most practical and effective strategies [22][23][24] to mitigate the seismic risk.…”

“…It was first proved that the rolling mechanism is very effective in filtering out input ground accelerations because of its limited rolling friction. Accordingly, several more sophisticated rolling-based isolation devices that have both restoring and self-centering capabilities because of gravity, such as cylindrical rods on concave beds or rails [10] and balls inside two concave or conical plates [11,12], were developed. These devices have been numerically and experimentally validated for effectively reducing seismic demand on the protected superstructures.…”

Performance of structure–equipment systems with a novel roll-n-cage isolation bearing

“…However, this shape causes equipment uplift and cannot prevent permanent equipment dislocation under strong earthquakes. To overcome this difficulty, spherical rollers inside two opposite concave plates are proposed in [31] as a rolling-pendulum system. This provides a gravity restoring force without permanent displacement but damping is still missing and uplift is exhibited.…”

Seismic behavior of variable frequency pendulum isolator

“…The other advantage of the sliding bearings consists of the maximum acceleration transmissibility equal to the maximum limiting frictional force. Some important studies on the effi ciency of a variety of sliding bearings have been performed by many researchers (Zhou et al, 1998;Hamidi et al, 2003;Tsai et al, 2003;Murnal and Sinha, 2004;Tsai et al, 2005;Panchal and Jangid, 2008). However, most of these studies were based on the two-dimensional (2D) planar model of the isolated structure subjected to unidirectional excitation, ignoring the bi-directional interaction effects of the frictional forces mobilized in the isolation system in two horizontal directions.…”