The "field laboratory" of Adapazari, where hundreds of buildings settled, tilted and collapsed due in part to liquefaction and ground softening, provides an exceptional opportunity to document the effects of ground failure on building performance. Moreover, there are a number of observations of damaging ground response that have not been documented previously. The seismic interaction between buildings and softened foundation soils is an especially important feature, as ground failure appeared to be more prevalent and severe adjacent to and under buildings than away from structures. Current guidelines, such as the California Hazard Mapping Program, are poorly defined regarding the effects of liquefaction on building performance and necessary mitigation measures. Considerably more building performance documentation and subsurface characterization are required to learn the lessons from this exceptional field laboratory on the effects of ground softening and failure on structures and the effects of soil-structural interaction and response on ground performance.
The primary goal of the proposed study is to develop well-documented case histories of building performance at sites undergoing moderate to severe ground failure, so that the profession can use these case histories to advance our understanding of these phenomena and enhance our ability to numerically simulate them. A parallel goal is to provide a comprehensive record of ground performance data in Adapazari and adjacent communities so that additional lessons can be learned.
This research project combines the talents of several professors and students who led and participated in reconnaissance efforts of the Kocaeli earthquake. It has been effectively coordinated through key Turkish professors who are sharing their expertise, data, and equipment. Existing aerial photographs offer the opportunity to coordinate the study and generalize findings. The team has access to detailed damage statistics collected by the Turkish government. Building systems for key case histories will be better documented, because ground failure appeared to be caused in part due to the dynamic response of the overlying structures. For example, ground failure was not pervasive in undeveloped areas, and taller buildings settled more than shorter buildings. Additionally, areas with significant ground failure contained significant structural damage. Due to the significant variations in subsurface conditions across Adapazari, efficient Cone Penetration Testing will be invaluable. But it is important to tie this type of testing with Standard Penetration Testing, where soil samples are retrieved, due to the presence of significant nonplastic, and sometimes plastic, fines in many of the deposits that softened as a result of shaking.