Abstract
Seismically induced settlement of buildings with shallow foundations resting on dry sand soils has resulted in severe damage in recent earthquakes. A multi-degree of freedom shaking table and a fixed container were manufactured and used to study the foundation settlement. Series of shaking experiments on the shallow foundation situated in a center of the container and atop of a dry sandy soil has been performed to identify the mechanisms involved to calculate the foundation settlement induced by earthquake shaking. In this research, the important factors are identified, including shaking intensity, the soil relative density, the degree of freedom and the building’s weight. Two relative densities (55 % and 80%) are used and three local magnitudes of earthquakes (5.8, 6.4, and 7.2) (Anza, Jalisco, and Guerrero) respectively with one and two degrees of freedom. The results of the shaking indicated that shallow foundation settlement on the dry sand increases with the increase of the local magnitude of earthquakes and maximum acceleration. In the case of Anza, the percentage decrease in the settlement between the relative density of 55% and 80% for systems (x and xy) is (47% and 42%) respectively. While in the case of Jalisco and Guerrero, the percentage decreases in their settlement and for the same systems is (11% and 57%), (36% and 36%) respectively. The degree of freedom has an impact on the foundation settlement; it is proportional to the degree of freedom. Also, the results show that the settlement decreases when the relative density of sand increases.
Highlights
For any land-based structure, the foundation is very important and must be strong to support the entire structure
These results showed that the settlement under multidirectional shaking in dry sandy soil can be larger than that gained in one-directional loading tests and this is identical to findings of [7]
These results are due to the high magnitude and maximum acceleration in the case of Guerrero comparing with the other cases, the time in the case of Guerrero is less than the time in the case of Jalisco
Summary
For any land-based structure, the foundation is very important and must be strong to support the entire structure. The settlement of soil below the shallow foundation in dry sandy soil underneath the seismic loading may be major damage to most structures throughout the earthquake. The waves may be increased the settlement, tilt and caused a reduction in the bearing capacity of shallow foundations due to seismic loading. The settlement of dry sands throughout the earthquakes under below one-directional loading within the laboratory was firstly studied in 1971 and 1972 [5,6]. Tokimatsu and Seed [8]advanced a procedure for estimating dry sand settlements because of earthquake shaking and recommended standard practice. The shaking table is manufactured to generate earthquake motions with a vast range of magnitudes and multi directions to evaluate an earthquake-induced settlement
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