The Landis Lecture. May 2, 2019

Copyright © 2019                               John F. Oyler 

May 2, 2019

The Landis Lecture

In 1991 the Landis family and the Epic Metals Corporation established the Landis Lectureship in honor of Donald Landis, a 1952 alumnus of the Civil Engineering Department at the University of Pittsburgh. Since then twelve world-class structural engineers have come to the campus to present relevant lectures. This year, in honor of my retirement, I had the privilege of presenting the Landis Lecture.

Since I had been asked to focus on the insight that a long career generates, I titled the talk “Eight Decades of Gathering Wisdom Regarding Civil Engineering”. Despite not being catchy, the title was precisely descriptive of the subject. Wisdom, fortunately, is not directly correlated with intelligence. Rather, it is the subconscious memory of thousands of relative experiences that have been properly evaluated.

I encountered wisdom when I was a junior engineer working for Dravo Corporation’s Engineering Works Division. I had an unusual assignment, troubleshooting problems encountered during startup of an iron ore pelletizing plant, a new venture for our company. Our engineering manager, Ernie Willison, took a special interest in the project and began haunting my drawing table. Frequently I would be interrupted by his looking over my shoulder and pointing out obvious (to him) mistakes that I had made.

I found this to be extremely frustrating; how could this old man be so smart? (and I so dumb?). Thirty years later I found that I had morphed into him. By now I was a high level Chief Design Engineer who spent his time involved in whatever technical problem was bedeviling our department. And sure enough, I had developed the ability to sniff out things that didn’t seem right, without knowing specifically how I knew they weren’t correct. That is wisdom.

My credentials as an expert on wisdom are impeccable. When I was quite young, my parents were concerned that I was “hyper”, never paid attention to what I was told and insisted on talking all the time. My father recited a poem to me. “A wise old owl sat in an oak. The more he heard, the less he spoke. The less he spoke, the more he heard. Why can’t you be like that bird?” Excellent advice.

Years later when my daughter Elizabeth talked me into joining the YMCA Indian Princesses, a father/daughter program with a Native American theme. The first step was the burning of our “white man’s names” and the adoption of Indian names. I instinctively chose “Wise Old Owl”. When we entered the username/password world, I used it as my username. 

Eventually this option was closed to me, as someone else had already chosen it, so I promoted myself to “wiseroldowl”.  That worked for a few years, till I tried to open a Google account. This required another promotion to “wisestoldowl”, which was accepted. Today, if you address an email to wisestoldowl@gmail.com, you will get an answer from me. That is indeed an impeccable set of credentials.

My claim to eight decades is based on the fact that my first visit to a construction site was in August, 1938. My father was employed by the Pennsylvania Turnpike Commission as Resident Engineer for two contracts on the original construction of the Turnpike, between New Stanton and Donegal. He enjoyed the job despite it was too far from our home in Bridgeville for him to commute.

Consequently he rented a room in a private home in Mount Pleasant, coming home on weekends and frequently on Wednesday evenings. On one such midweek visit home he suggested I go back with him the next day, an opportunity I exploited immediately. I spent the next two days bumping around the job site in a pickup truck, riding in bull-dozers, and generally absorbing everything I saw. Pretty heady stuff for a seven-year-old!

Having established my credentials for the subject I then discussed three traits that I believe are essential for a successful engineer – focus, judgment, and creativity – and proceeded to discuss examples of each.

The Florida International University (FIU) pedestrian bridge collapse is an appropriate illustration of the consequence of losing focus. The University is separated from the neighboring community of Sweetwater, where four thousand of its students live, by a busy eight-lane highway. It is ideal location for a pedestrian bridge, much like the ones Pitt and Duquesne have over Forbes Avenue.

The idea of a pedestrian bridge moved forward quickly once it was determined federal funding was available. It was determined it could be constructed for well under two million dollars; a project was born! Unfortunately it almost immediately became more and more complicated.

Once the project was announced, a variety of organizations with ambitious agendas began to suggest changes. FIU is still considered a “johnny-come-lately” among Florida universities and is eager to do things that enhance its reputation. FIGG is a prominent Florida bridge design firm that “creates bridges as art”. Between the two of them the design was grossly distorted.

Instead of designing a conventional through truss bridge, they decided to utilize a huge I-shaped girder with the roof being the top flange and the deck the bottom flange. The web, instead of being solid, would be a series of diagonal struts functioning like truss members. The whole structure would be prestressed concrete. Large steel tendons would compress the roof and deck transversely and longitudinally and the web diagonals longitudinally.

By compressing the concrete initially, the members that ultimately would receive tensile loads would merely see the compression reduced significantly. This is a common practice that had not been previously applied to a complex design of this type. 

The next complication was the decision to create a work of art by pretending it was a cable stayed bridge. This entailed adding a tall pylon and sloping hangers that were strictly cosmetic, with no practical function whatsoever. Once this decision was made it was decided that the web diagonals should be aligned with the hangers, even though this dramatically increased the loads in them.

The net result was a hopelessly distorted design, not to mention one whose cost had risen to over twelve million dollars. Not to worry, the University was receiving a signature structure that would show the world how great they were. The deck had been widened to thirty-two feet, converting it from a simple pedestrian bridge into a “destination” and entertainment venue.

The huge I-shaped girder was cast in a location close to the bridge piers. The tendons were stressed, generating compression throughout the girder. The girder weighed nine hundred and fifty tons at this point. It was carefully jacked up, traffic on the highway was stopped, and the girder was transported to the piers and put in place.

It was an occasion for “high-fives”, “fist-bumps”, and “pats-on-the-back” for all concerned. FIU was well on the way to having its icon; FIGG could soon add another “bridge as art” to its resume.

Five days later the Engineer-of-Record, Dennis Pate, called the Florida Department of Transportation and left a voice-mail message to the effect that they had found a crack in the deck, but that it wasn’t a safety issue. Midday the next day a workman was adjusting a tendon near the crack when the whole girder collapsed, killing him and five people in vehicles on the highway below.

Because of the massive litigation associated with this disaster, information on the investigation by the National Transportation Safety Board has been limited. They have stated however that the joint at the base of the diagonal where the failure occurred was insufficient for the loads it was required to support.

I have always believed that a properly designed bridge is inherently a work of art. I do not believe a “bridge designed as art” is inherently properly designed. Lack of focus is frequently a precursor of failure.

The other highly publicized structural failure in 2018 is the TransBay Transit Center in San Francisco. The 1989 Loma Prieta earthquake destroyed the transportation terminal in the Mission District; since then a temporary transit center has served to tie together ten bus lines, the Bay Area Rapid Transit, and Caltrain.

Last year a major project, replacing the temporary center with a modern transportation hub, “The Grand Central Station of the West”, was completed and put into service. The TransBay Transit Center. It is an impressive six-level structure one small city block wide and one thousand four hundred feet long.

The roof of the Center is a linear park, 5.8 acres of green space, with mature trees, fountains, playgrounds, and an entertainment venue. In addition to providing spaces for the various transportation modes, the lower levels include shops, restaurants, and public art. Once again, there was a lot of celebration last August when the Center was opened to the public.

In mid-September a workman installing ceiling panels reported what he thought was a crack in a girder spanning Fremont Street. In no time his suspicions were confirmed and the Center evacuated. Further inspection determined the same problem existed in another nearby girder. Since then hydraulic jacks have been in place in the middle of Fremont Street, holding up the girders.

For some reason it has been easier to get information on this problem, information that is troubling to anyone knowledgeable about structural design. The girders in question are steel plate girders, each eight feet deep and spanning eighty-five feet. 

The girders are tapered, deeper at the middle than at their supports. This requires a butt weld at mid-span, right where the stress is the greatest. The steel is ASTM A572, grade 50, a high-strength low-alloy (HSLA) grade that is well known to be brittle, especially in thick sections.

The bottom flanges of the girders are thirty inches wide and four inches thick; the cracks extend completely across them. Flanges of this thickness are always subjects of concern because of uncertainty about properties in the center. 

Another concern is the effect of residual stresses associated with welding such a thick component, an effect typically minimized by stress relief after welding. Apparently “the code” did not require stress relief.

Another aggravating factor was the fact that the girders also carried the loads from the bus level below them, concentrated loads that were applied at mid-span by hangers that were extensions of the web through holes in the bottom flange.

Introducing a hole in a tension flange produces a concentration of stress at that point, frequently resulting in doubling the magnitude of the stress. If that weren’t already a serious problem, the decision to burn another hole, at right angles to the first one, to permit welding the web hanger to the flange, generated another stress concentration.

Inspection of the failed area indicates that the crack started in the corner of the second hole and propagated across the full flange. It also indicates that the steel halfway through the flange thickness had been transformed to very brittle martensite, either because of the welding or the flame-cutting of the hole.

There are so many errors of judgment involved in this situation that it is difficult to place the blame on one specific blunder. Whenever I attempt to discuss the problem with a competent structural engineer, the immediate reaction is that this is a classic example of poor judgment, compounded six times.

At this point in the lecture I reminded the audience that these bad examples were rare occurrences and that the civil engineering profession had thousands of successes for every failure. I then listed four recent local successes as good examples.

First was Brayman Construction’s replacement of two bridges on the Pennsylvania Turnpike in a weekend. At midnight Friday they shut down the Turnpike, demolished two major bridges, slid their replacements into place, and had traffic back to normal by 5:00 am Monday. 

Second was the reaction of PennDOT District 11 to the landslide on Route 30 last Spring. With the help of Gannett Fleming and a lot of red tape cutting, they were able to diagnose the problem, rebuild the hill-side, and have the highway back in operation in three months.

Similarly the reaction to the fire on the Liberty Bridge was noteworthy. The fire was so severe that it buckled a major compression strut near one of the piers. Coordinated by PennDOT District 11 a large collection of local engineers analyzed the bridge in its deformed condition, jacked the failed joints back to their original position, and installed new members capable of taking the required load.

Finally, this winter PennDOT District 12 was able to maintain traffic on I-70 right at the West Virginia Line while a long wall mining machine tunneled beneath it. A group of folks from our department – Tony Iannichione and Luis Vallejo, plus several graduate students – participated in instrumenting the roadway and its embankments throughout the process. Eventually the entire highway settled four feet, without any major damage or disruption to traffic.

Four examples of effective engineering. An equally positive story is the one I used to illustrate the trait of creativity – the Bayonne Bridge. Designed by Othmar Amman, the Bayonne Bridge was the longest (1675 feet) steel arch bridge in the world when it was opened in 1931. 

Spanning Kill von Kull between Staten Island and Bayonne, the bridge was designed with a clearance of 150 feet above high tide, enough to permit the largest aircraft carrier in our fleet to pass under it safely. This also permitted access for Panamax vessels to bring containers to the Newark-Elizabeth container terminal, largest on the eastern seaboard.

The term “Panamax” defines the largest vessels capable of transiting the Panama Canal, vessels that can carry 4000 containers. Early in this century shippers began to pressure the Panama Canal Authority to expand enough to permit much larger vessels to pass through the canal.

The new locks in the Panama Canal can handle vessels with a beam of one hundred and sixty feet, vessels that can transport 13,000 containers at a time. To accommodate these massive ships, eastern seaboard ports have had to deepen their channels to fifty feet. Newark-Elizabeth had a different problem – the new vessels were too tall to pass under the Bayonne Bridge.

The estimated cost of demolishing the bridge and replacing it with one with adequate clearance was more than could be justified. Fortunately some unidentified independent thinker eventually pointed out that there was nothing wrong with the bridge; it was the deck that was the problem. Why not just raise the deck? Shorten cables in the middle, add posts near the piers, and redo the approach ramps.

Excellent idea, one that could be implemented well less than a billion dollars. A joint venture headed by Kiewit and Skanska was awarded the contract. We were aware of this project thanks to two of our alumni – Scott and Angie Hunter, class of 2007 – who have worked for Kiewit since graduation. They come back regularly to make presentations to our students. 

The approach ramps were constructed using massive precast tub-shaped concrete segments, each of which weigh one hundred and ten tons. They were cast in Hampton Roads and shipped up the east coast. Scott somehow was involved in trying to find an unloading facility in the New York harbor that could handle such large pieces.

It turns out there was only one crane that could make that lift and its owner was taking advantage of his monopoly to charge an excessive fee for renting it. At some point Scott commented that for half that fee they could build their own crane. Much to his surprise, he was given the opportunity to do just that.

He then proceeded to design a stiff-leg derrick from scratch and to oversee its fabrication and assembly. One evening I received an email with a photograph of the crane unloading the first of the segments to be delivered. No caption was required; it was obvious that Scott’s design was a success. They ended up saving money, as well as acquiring a valuable asset.

When his boss commented “You must have had a good steel design course at Pitt”, Scott replied, “Yes, I did, but I didn’t use it for this design. My design was based on the fundamentals I learned in Statics and Mechanics”. That’s an engineer!

Like all good preachers I closed my sermon with a charge, advice to engineers of all ages.

Be a polymath, someone interested in the technology of all the specialists with whom you interface. Be willing to take a change, to accept a challenge that seems daunting. And, finally, believe in yourself and your ability to achieve.

Pulling together this lecture was an humbling experience, particularly when I thought about the stature of the previous lecturers. Nonetheless I enjoyed it and am honored that I was given this opportunity.