Peck the Mentor:
Keep It Simple
I believe the year was 1985. I was a young professor at Texas A&M University and was excited to have been invited to speak in Albuquerque about some of my pressuremeter work. When checking the program, I saw that Professor Peck was on it as well. My luck increased when I found myself sitting next to Ralph Peck at lunch. I asked a number of geotechnical questions, which he patiently addressed. One of them was related to the famous three charts to estimate the size of spread footings on sand.
As you recall, these charts give the allowable pressure for 1-in. settlement as a function of footing width for different SPT blow counts. Each chart refers to a different relative embedment depth. As background, I always tell my students to leave the data points on the design charts when they propose the design curves so that the engineer can get a sense of the scatter associated with the design curves. I had not seen the data points associated with these three simple spread footing design charts so I asked, "Dr. Peck, where are the data points associated with these charts?"
He looked at me with a grin and said "Can we talk about something else?" I smiled politely, but still wondered. Fortunately he added, "You know it was the early days; Terzaghi and I did not have much data, but we had to do something. We had some observations on small buildings with basements, but that was it. So, we drafted this simple solution merging bearing capacity and settlement, published it, and the next thing we knew, people were using it. That's just the way it went." So, I went back to my students with one more of Peck's great lessons which I interpreted to say: if you want something to be used by the profession, you have to make it both useful and simple. I did add that they still should leave the data points on the design charts.
Jean-Louis Briaud, Ph.D., P.E., F.ASCE
This letter is an excerpt from the Geo-Strata Feature on Professor Peck, Geo-Strata September/October 2008.