Comparison between cyclic and dynamic rocking behavior for embedded shallow foundation using centrifuge tests

Abstract

Designs allowing the rocking behavior of the foundation during earthquake have been introduced to reduce the seismic load on the superstructure and the ductility demand on the structural column. In addition, several studies have been conducted on rocking foundation based on the slow cyclic and dynamic tests by assuming the structure as a rigid oscillator. However, when structural bending is included, the rocking behaviors of the foundation for the slow cyclic and dynamic tests are different. Therefore, a clear description of each method and how each behavior is different should be investigated by considering structural bending motion. To fill the gap between cyclic and dynamic rocking behaviors, embedded foundation models with various slenderness ratios of the systems were investigated using horizontal slow cyclic tests and dynamic tests in a centrifuge. Test results show that the rocking foundation was affected by structural bending. The overturning moment in the dynamic test determined by the conventional method was different compared with results obtained from the slow cyclic test due to the structural bending motion. Finally, the overturning moment was re-evaluated by considering structural net displacement, and the re-evaluated dynamic overturning moment matched the results from the slow cyclic tests.