Professor Steve Kramer officially has a collection of Norman Medals. Kramer was recently honored with a second Norman Medal after receiving his first award eight years ago. Bestowed by the American Society of Civil Engineers, the Norman Medal recognizes the best paper of the year from ASCE’s more than 35 technical journals. In the history of the award, which dates back to 1874, only a handful of people have been honored more than once.

Kramer and his Ph.D. student C.H. Wang received the award for their paper “Empirical Model for Estimation of the Residual Strength of Liquefied Soil,” which describes an innovative way to estimate the residual strength of soil following liquefaction. Liquefaction is an important problem in geotechnical earthquake engineering and can cause soil to behave like a liquid during sudden environmental changes, such as earthquakes.

When soil liquefies, its strength can be reduced to a small fraction of its initial strength. As a result, soil that was stable prior to an earthquake can become extremely unstable, especially in areas with sloping ground or level ground adjacent to rivers and waterfront structures. Flow slides occurring at such sites often involve large masses of soil flowing extremely quickly and destructively (for example, in the Oso mudslide in 2014). The effects of such slides, particularly how far they travel, depend on the residual strength of the soil. 

The methodology developed by Kramer and Wang takes probability into account, which allows for more rational estimations of soil strength. To develop the new methodology, they analyzed a series of case histories for flow slides. In addition to estimating the probability distribution of residual strength, Kramer and Wang eliminated inertial effects, which can bias the estimation of the actual soil strength. They also accounted for conditions in which phenomena other than flow slides develop during liquefaction, which contribute to scatter when estimating residual strength.

Kramer’s first Norman Medal in 2009 was received together with alumnus Roy Mayfield for a paper titled “The Return Period of Liquefaction,” which presented new procedures for evaluating the potential for triggering of liquefaction.

This is the second year in a row that a UW CEE faculty member has received the award. New faculty member Brett Maurer, who joined the department in January 2017, was one of the recipients of last year’s Norman Medal.