Settlement of Strip Footings on Sand Subjected to Cyclic Loading

There are many cases in which the foundation, in addition to static load, is exposed to cyclic loading, such as earthquakes, traffic loads, and machine vibrations. In this laboratory study, the effect of foundation width, sandy soil density, number of loading cycles, static and cyclic overhead intensity on cyclic strip foundation settlement has been investigated. The soil material used in this research is poorly graded medium sand (SP). The foundation model has a width of 5, 7.5 and 10 cm and its length is 34 cm. In medium and dense sandy soils, the average amount of foundation settlement in the first loading cycle is about 46 and 51% of the total cyclic settlement, respectively. Medium-density sandy soils below the foundation have failed at a settlement of 22 to 27% of the foundation width. The dense sandy soil beneath the foundation has failed at a settlement of 33 to 43% of the width of the foundation. The lower the total overhead entering the soil, the more loading cycles the soil can withstand to fail; That is, with increasing static and cyclic overhead, the soil is failed in a smaller number of cycles. Due to the creation of permanent settlements under the effect of cyclic loads, in the design of foundations under the effect of this type of load, the amount of predicted settlement must be less than the allowable amount.