This paper presents a field test program of a large-scale soil–footing-structure system designed with a rocking foundation in a cohesive soil to examine the behaviour of the system and to provide case histories for possible performance-based seismic design of foundations. The rocking system was subjected to slow cyclic loadings at various drift ratios up to 7%. Twenty-four tests were conducted for foundations with varying initial factors of safety against the bearing failure, loading directions, rotation amplitudes, and embedment. A geotechnical investigation was carried out to determine soil properties before and after the experiments. The system performance indices, such as damping, stiffness, settlement, and re-centering capability, were quantified and compared with the published literature. Field test results showed that the strength and unit weight of soils at footing edges were increased due to rocking, for the present cohesive soil. The rocking moment capacity increased slightly with the increasing soil strength. An empirical equation for the secant stiffness was developed. The rocking system on the cohesive soil exhibited superior performance in terms of small residual settlement and large re-centering capability. Footing’s mechanical response was quantified using strain gauge readings. The footing remained elastic in tension; the transient soil–footing contact areas were estimated with strain gauges, and they agreed very well with the measured or calculated contact areas.

An earthquake of moment magnitude M_w 7.8 struck Nepal at 06:11 UTC on April 25, 2015. Field reconnaissance focused on the geotechnical engineering aspect of the earthquake was carried out in the Kathmandu Valley and regions near the epicenter. This paper presents briefly the geology of Nepal, the accelerogram, and results of standard penetration tests at selected sites in the valley. The study shows the failure case histories including landslides, road embankment settlement, bridge foundations and abutment damage, and liquefaction. The paper also highlights the impact of local soil properties and basin and ridge effect on the severity of damage.

This paper reports the structural failures and collapse of heritage structures in Kathmandu Valley, Nepal, during the 2015 Nepal earthquake, and presents preliminary findings regarding the causes of failures and collapses. Field reconnaissance was carried out immediately after the main shock (M_w 7.8) on April 25 and the strongest aftershock (M_w 7.3) on May 12. It was observed that the performance of heritage structures was influenced by the combination of several factors, including structural and architecture type, configuration and structural deficiency, local site effects and ground-motion characteristics, age and maintenance level, material quality, etc. It was observed that dome structures performed very well, followed by pagoda (tiered temple), and shikhara structures were found as the most vulnerable structures. Moreover, it was observed that structures that had been seismically retrofitted and well maintained appeared to perform well. Some recommendations are made to improve the seismic performance of the heritage structures in Kathmandu Valley.

Rocking shallow foundations may act as a good mechanism for base isolation that limits the seismic force to the superstructure during strong seismic events; however, a lack of comprehensive field investigation might have limited the use of rocking foundation. This paper presented a field study of a rocking shallow foundation resting on a natural soil deposits in Alberta, Canada. The foundation system consisted of a 1.5 m by 1.0 m concrete footing, column, and deck to simulate a prototype bridge system. A geotechnical investigation was carried out to determine soil conditions before and after the experiments. The footing was subjected to slow cyclic loading which consists of 4 to 5 packets of which each contain 3 to 4 cycles of similar displacement amplitude. The drift ratio was increased to a maximum of 5%. The estimated factors of safety against bearing failure ranges from 4 to 22. Nonlinear behaviour of the foundations and underlying soil was evident; changes in the physical and mechanical properties of underlying soils were characterized. Energy dissipation, residual settlement, and stiffness degradation observed in the tests were discussed.