The Use of Limestone Sand for the Seismic Base Isolation of Structures

Abstract

The possibility of the use of a layer of natural material under foundations for seismic base isolation was investigated. The dissipation of seismic energy of a low-cost natural material with adequate thickness, bearing capacity, and lateral and vertical stiffness, which can serve as an optimal solution for seismic base isolation under the foundations of many structures, was tested. This paper presents the results of a brief experimental study to determine the effectiveness of ordinary limestone sand under the foundation of a cantilever concrete column to increase its seismic resistance. The behavior of small-scale columns with three substrates below the foundation (rigid base, the thin layer of limestone sand, and the thick layer of limestone sand) was investigated by the shake table. The column was exposed to a set of horizontal base accelerations until structure collapse. It was concluded that a layer of limestone sand of appropriate thickness and compressibility can serve as the means a seismic base isolation. The nonlinear numerical model for the dynamic analysis of planar concrete structures coupled with soil is briefly presented and verified by the performed experimental tests.

Hybrid geotechnical and structural seismic isolation: Shake table tests

“…20 As for the sliding interface, Qamaruddin et al 21 suggested that when the friction coefficient was greater than 0.40, no sliding occurred in most real earthquakes. Banovic et al 22 verified the isolation effectiveness of a limestone sand pad by testing a smallscale cantilever concrete column. Recently, Hu and Nakashima 23 conducted a comprehensive parametric study on the maximum responses of a two degree-of-freedom sliding isolation system under harmonic excitations and derived a theoretical solution for the response corresponding to the sliding-sliding case.…”

“…Shake table tests for whole brick masonry buildings with a sand/gravel pad are still lacking; however, there are shake table tests on either solid concrete blocks 33 or reinforced concrete columns. 22 Thus, the existing conclusions drawn were mostly qualitative and might not represent the structural response of a real masonry building. Furthermore, during earthquakes, the movement of the superstructure with a sand/gravel pad constructed before might be limited because part of the structure and the foundation might be bounded by the surrounding soil, which is a practical concern.…”

“…Shake table tests for whole brick masonry buildings with a sand/gravel pad are still lacking; however, there are shake table tests on either solid concrete blocks 33 or reinforced concrete columns 22 . Thus, the existing conclusions drawn were mostly qualitative and might not represent the structural response of a real masonry building.…”

Geotechnical Seismic Isolation System Based on Sliding Mechanism Using Stone Pebble Layer: Shake‐Table Experiments

“…Patil et al [2] performed experiments and analytical work on a structural model with isolated footing using river sand and found encouraging results. Radnić et al [3] and Banović et al [4] found by shake-table study that a layer of limestone sand of appropriate thickness and compressibility can serve as seismic base isolation material. Experimental studies with dune sand and lightweight expanded clay as sliding layers in adobe buildings in Iran can be found in [5].…”

Shake Table Study on the Efficiency of Seismic Base Isolation Using Natural Stone Pebbles

“…A series of numerical simulations and a parametric study on seismic base isolation using rubber-soil mixtures can be found in [5]. Radnić et al [6,7] found from shake table tests that a thin layer of plain sand under the foundation can reduce seismic forces to a cantilever concrete column by over 10%. Xiong and Li [8] analyzed seismic base isolation using rubber-soil mixtures (RMSs) based on shake table tests and a parametric numerical study in [9].…”