This book is an interview transcript with Henry J. Degenkolb and it is the first volume, along with 29 other volumes, that were written as part of the EERI Oral History Project. The project’s goal is to publish interviews with prominent figures in the earthquake engineering community in order to preserve some of the rich history and fascinating stories over the passing decades.
All of these volumes are available online for free: https://www.eeri.org/oral-history-series. It certainly felt a little anachronistic to read written interview transcripts in the current age, but I enjoyed it. Perhaps the newer volumes can also be published in audio format (i.e. podcast). I think that would be awesome!
Here are some of the things I learned reading the book:
Henry J. Degenkolb graduated from Berkeley and began practicing in 1936. Back in those days, structures were designed for vertical loads only with negligible consideration for earthquake. Note that this was after the 1906 San Francisco Earthquake. Nevertheless, some engineers made an effort to tie the building together a little better. This was known at the time as “California Practice”.
Henry spent a lot of his career chasing earthquakes (i.e. performing earthquake reconnaissance after it happened). The damages he’s observed over the years dramatically shaped his whole attitude towards building design. He tended to have a more wholistic view and believes in quality building design. Some may call him conservative, but I think he would call it “prudent”. Quote: “Some of us used to argue that you shouldn’t really get your structural license until you’ve chased an earthquake. I’ll tell you - the difference between reading a report and seeing it - there is no comparison.”
He felt that engineers shouldn’t take a legalistic attitude towards building design. Just because a design satisfies the building code doesn’t mean a quality performing building. On the other hand, many building officials see the code as an ordinance for enforcement. He gives an example that driving 56 mph is dangerous, but 55 mph is perfectly all right. Sadly earthquake engineering isn’t that precise
Apparently there was a feud between Henry and Professor John Blume and Nathan Newark. The story goes that Professor Blume published some literature and textbook promoting the use of concrete, and how it could be just as ductile as structural steel if detailed properly. Henry wrote a critique of Professor Blume’s work, mostly criticizing the lack of knowledge inherent in concrete, as well as the lack of testing of joints
Apparently Henry’s critique was not really “published”; more so “distributed” in a private manner. The steel industry folks leveraged Henry’s critique to further promote steel. Some of the criticisms were valid, but most were subsequently addressed by professor Blume. The result was a delay in adoption of some of the concrete detailing recommendations. John felt that the critique likely did more bad than good. His intent was to improve how non-ductile detailing can be revised to be better, not a way to supplant the use of structural steel for concrete. Because of this whole ordeal, John became known as the “concrete guy” whereas Henry became known as the “steel guy”
Back in those days, earthquake engineering research tended to be more theoretically based. In other words, applied (experimental) research was highly looked down upon, and the university preferred to work with mathematically equations, higher abstract theory, etc.
In those days, structural engineering was more of an itinerant profession. There was often no stable work so engineers often traveled and worked a few months here and there. In San Francisco, there were practical no structural jobs back then except those who worked on the Bay Bridge or Golden Gate Bridge
The first earthquake load factor (i.e. how much earthquake excitation a building might experience) was based entirely on empirical observations and not mathematically oriented! Note that this is in the 20th century
The 1985 Mexico Earthquake was very unique. Typically the frequency content of earthquake ground motions are high and tall buildings are somewhat isolated because of their long period. However, the Mexico earthquake had longer-period motion that resulted in collapse of 6 to 15 story buildings which were most vulnerable. This was very unexpected as high-rise structural steel buildings were always thought to perform excellently in earthquakes
There used to be a “gentleman’s agreement” that US engineers didn’t look at Japanese earthquakes, and vice versa. It was though that it would be an insult to them because they were competent enough to examine their own earthquakes. This ended in 1971 when Japanese engineers came to observe the San Fernando earthquake, so that kind of broke the ice
Earthquake engineering is a learned profession. However, unlike other practiced profession like medicine, where you can see what happens to a patient within a short time, a building may go up to 50 years without ever being tested. Because of this, the adoption of new knowledge is quite slow. Another challenging aspect of earthquake design is that it is such an extreme event. You could properly design a structure for earthquake, or completely do a poor job. And for 400 out of 500 years, your design won’t be tested and people won’t know
Gravity design of buildings is mostly a commodity and difficult to mess up with the exception of occasional serviceability issues. Seismic design is a complete different beast. The problem is that no one can tell the difference in quality until an earthquake happens. It is also possible that an earthquake doesn’t happen at all within the 50 year design life of a particular building. You could do a bad job without anyone knowing
Henry always believed in ductility. With earthquakes, the stronger you make a structure, the more load it will attract. The key is to design for ductility not strength.
Henry believes there are two ways to run an engineering firm: “as a profession” or “as a business”. He believes that doing things the “business way” (i.e. enlarging, running a business, production-line type of things) is no way for entering or bring up the profession. There is a lack of mentorship in the latter, and generally young engineers lack the inquiries and discussions needed fully develop
Henry realized that it is nearly impossible to hire good senior engineers. Those that are good tend to stay within their firms. Consequently, it is crucial to hire and develop young engineers from the beginning
In general, architects make 6~8% of the total project cost. Out of that 8%, the structural consultants usually make a quarter of that. All in all, it’s about 1% of the total building cost, minus the price of land. For comparison, real estate agents make roughly 5% commission, including price of land. On top of the abysmally low fee, there is also an immense amount of liability that’s undertaken. You don’t even need to make a mistake. Someone else could mess up and everyone gets sued, with lawyers taking away 40% on a contingent basis.
In his opinion, for the developers, the desire for quality building seems to be subordinate to the desire to build it quickly and cheaply to get a financial return. The profit margin is often razor thin for commercial/residential construction jobs. Furthermore, since engineering has become a commodity, jobs often go to the lowest bidder. There is also incentive on the part of the architects to hire the cheapest engineers, thus pocketing more of the design fees.
Henry believes that the class of projects that most need competence is residential. This sector is where the biggest chances are taken and the worst things are found. Quoting “Gresham’s Law of Engineering”: “bag engineering drives out good engineering for the people who need it most”. At the end of the day, it is cost-prohibitive to properly design a quality timber building given the limited fee. Timber design is actually very complicated and time consuming given its many connections and fuzzy load paths. However, for every 9 engineer that refuse to do sub-par rushed work, there will be 1 engineer willing to take the job and take the risk.
In other words, you will become bankrupt trying to do quality work. Imagine taking an exam but only have 30 minutes to do it. And the professor may or may not count it towards your grade.
Massive buildings and landmark structures tend to go to a select few firms. For example, Skidmore, Owings and Merrill designed roughly two-thirds of the San Francisco skyline. This is purely a matter of risk. The person working for the developers can’t go wrong picking a well known firm with a proven track record. The end product may be good or just decent, but you can’t be criticized for this selection. There is no sense in risking it with another smaller or medium firm.
Henry basically priced his firm out of the average building design because its service is too expensive. The mantra has always been to offer the highest quality structural engineering service, which means being willing to say “no” to owners or architects if it doesn’t make sense. For example, some engineers will do whatever the architects want as long as it doesn’t violate the words of the code. This is more of a legal exercise than an engineering one. Often a structure can meet the wording of the code but still perform terribly in an earthquake.
Henry was somewhat skeptical of base isolation systems because ground motion of some ground motion records recorded up to 36” in displacement and his believes some aspects may be overlooked
He is also not too fond of probabilistic analyses. Quote: “If you don’t know anything, you must assume something, and you manipulate it with a lot of mathematics, and then you’re supposed to get something useful. I can’t quite believe it”
One big area of building design that he thinks is being overlooked is the base attachment (i.e. how the structure is attached to the foundation/ground). The assumption of fixity at the base completely changes the outcome. Soil-structure interaction is still not adequately considered, at least on the practice side of things
He gave an example from the UCSF Moffit hospital. From the result of an elastic analysis with fixed base assumption, there was enormous amount of uplift in several places (up to 2000 kips). The design ended up calling for many anchor rods and piles drilled deep into the soil. He believed that base rocking may be an effective energy dissipation method, and that rigidly attaching the base to the ground may do more harm than good