Lehigh University’s Fritz Engineering Laboratory marks its centennial in 2010. At the heart of the laboratory has been a series of machines for testing the tensile and compressive properties of materials. For slightly more than half of its hundred-year history, Fritz Lab has been the home of what at the time of its dedication in 1955 was the world’s largest universal testing machine, a photo of which appears here and on the cover of this issue of Technology and Culture. More about that machine in a moment, but first, something about the lab itself and the man for whom it is named. John Fritz (1822–1913) initially made his mark as superintendent of the Cambria Iron Company, where in the late 1850s he introduced the concept of the three-high rolling mill, which greatly facilitated the manufacture of iron railroad rail. In 1860, Fritz was hired by the fledgling Bethlehem Iron Company as general superintendent and chief engineer. Expanding rapidly under Fritz’s leadership, Bethlehem Iron would subsequently evolve into the Bethlehem Steel Corporation. Five years after he went to work for Bethlehem Iron, Asa Packer of the Lehigh Valley Railroad established Lehigh University, with Fritz among the trustees—thereby helping to establish a longstanding working relationship between Lehigh and Bethlehem.

The 1907 failure of the Quebec Bridge made it clear that better facilities were needed for testing structural-building members, and very likely this disaster was on Fritz’s mind two years later when he told the president of Lehigh, Henry Drinker, that “you need an up-to-date engineering laboratory and I intend to build one for you.” At age 87, Fritz supervised the design and construction of the new laboratory, which was subsequently named in his honor. The building was a quarter-size version of one of the shops Fritz had built for Bethlehem Iron. The equipment he specified included an 800,000-pound Riehle universal testing machine, capable of testing twenty-foot structures in both tension and compression. The new Fritz Lab and its testing equipment propelled Lehigh into a position of leadership in materials testing and structural research, especially in the area of reinforced concrete, then coming into vogue, but also with regard to various new alloys of steel. For example, Fritz Lab tested various elements for a number of Bethlehem Steel bridges, including the George Washington Bridge connecting New Jersey and New York City. Bethlehem Steel had also designed the cable anchorages for the Tacoma Narrows Bridge (the infamous Galloping Gertie). The anchorages had been tested at Lehigh prior to erection, but during the subsequent investigation into the bridge’s collapse, they were tested again on the Riehle machine. Much to the relief of Bethlehem Steel, it was determined that the unstable, narrow, and shallow deck structure had been at fault, not the anchorages.

Two other examples of testing done on the Riehle machine were the steel plates manufactured by the McClintic-Marshall Construction Company for the Gatun lock gates of the Panama Canal and the structural steel used in the Golden Gate Bridge. Both Howard McClintic and Charles Marshall had been Lehigh graduates, class of 1888, and their Pittsburgh firm was described variously as the nation’s largest, or second largest, independent steel fabricator until it was acquired by Bethlehem Steel in 1931. McClintic-Marshall, operating as the Fabricated Steel Construction Division of Bethlehem Steel, also did the actual construction of the Golden Gate Bridge, using steel manufactured in Bethlehem, tested at Lehigh, fabricated and sub-assembled in Pottstown and Steelton, Pennsylvania, and shipped by rail to Philadelphia and then by boat to California through the Panama Canal—all this suggesting the close ties between the university and its graduates, its testing laboratory, and the Bethlehem Steel Corporation. For a period of time, Fritz Lab was directed by Willis Slater, who had formerly worked for the National Bureau of Standards (NBS), and there was a close working relationship between the laboratory and NBS, especially with regard to promoting research. Slater introduced the graduate civil engineering curriculum to Lehigh, with the first M.S. degree awarded in 1929, and the first Ph.D. in 1941.

Following World War II, it became clear that the Fritz facility was increasingly limited in its testing capabilities, especially for structures fabricated from large-scale forgings and rolled sections such as those used in contemporary buildings, bridges, ship hulls, and aircraft components. Although it was the world’s largest when installed, the lab’s Riehle had, within a few years, been surpassed by larger testing equipment at NBS. Because the Riehle was incapable of handling full-size specimens, test results with smaller material samples had to be scaled up, and there was always the danger of errors in extrapolation. In an effort to assure adequate safety margins, structures would often be overbuilt. With the active support of the Bethlehem Steel Corporation, Lehigh University set out to expand Fritz Laboratory and install new testing equipment. This project was spearheaded by Professor William Eney, chairman of the Department of Civil Engineering and Mechanics and director of the lab. Following in the mode of John Fritz before him, Eney insisted that the new testing equipment be the best available.

Fig. 1 The five-million-pound-capacity universal testing machine at the expanded Fritz Lab in the 1950s. (University Libraries Special Collections, Lehigh University. Reproduced with permission.)

In what for the time was a major construction undertaking at a cost of approximately $1.2 million, Lehigh, in cooperation with Bethlehem Steel, contracted for a seven-story addition to the original Fritz Lab. This addition was designed to accommodate a new, five-million-pound-load-capacity universal testing machine, designed and built by Baldwin-Lima-Hamilton (BLH), a corporation recently formed through the merger of two locomotive manufacturers and a general machinery producer (figs. 1 and 2). Standing approximately 60 feet above the test floor and extending 16 feet below, the new machine weighed more than 450 tons. It was capable of testing specimens of up to 40 feet in either compression or tension. The load on a specimen—which can range from a low of approximately 20–40 pounds to a maximum of 5 million pounds—is applied through a hydraulic cylinder actuated by means of an electric pump capable of exerting 3,000 pounds-per-square-inch of pressure against a fixed-bed piston. This cylinder, which surrounds the piston, is attached to two 62-foot vertical screws, which are located within the machine’s vertical columns (and are thus hidden from view in figure 1). A height-adjustable “sensitive” crosshead, also attached to the screws, applies the desired load to the test specimen, either in compression if it is mounted on the fixed bed below the crosshead, as in figure 1, or in tension if it is mounted above the crosshead and below a second “tension” crosshead supported by the machine columns above. In addition, the BLH machine can test for flexure reaction in girders or trusses up to 120 feet in length.

Although two other machines of similar load capacity existed at the Bureau of Reclamation in Denver and at the Philadelphia Navy Yard, the advantage of Lehigh’s new machine was the size of the specimen it could accommodate. This new capability meant that engineers could now test actual, full-size structural members. In addition to the new BLH machine, the expanded Fritz Lab was also outfitted with a Swiss-manufactured Amsler dynamic-load machine designed to test structural members in fatigue under conditions approximating actual usage. The lab, with its equipment both old and new, was now capable of handling a wide range of testing and research functions. Its capacity to test pre-stressed concrete-bridge girders made the state of Pennsylvania a leader in this form of construction. Other projects included the analysis of the steel anchor bars for suspension-bridge cables, such as those forged by Bethlehem Steel for use on New York City’s Othmar Ammann–designed Throgs Neck Bridge, and testing of the structural frame for Telstar, the first major communications satellite.

Fig. 2 Cross-section schematic detailing the operation of the universal testing machine. (University Libraries Special Collections, Lehigh University. Reproduced with permission.)

Allen Astin, director of the National Bureau of Standards, delivered the dedication speech for the expanded Fritz Engineering Laboratory on 14 October 1955, an event attended by over 300 industrialists and engineers from across the country. A variety of demonstration tests were carried out that day, including the cracking of a chicken egg to demonstrate the BLH machine’s low-end compression sensitivity. The successful “hatching” of the chick Fritzie was a media hit as well as evidence of the enormous machine’s wide range and versatility. Astin was pleased to note that “with these new important research and testing tools, the staff of the Laboratory can look forward to a long period of professional leadership in the field of experimental stress analysis.”

That position of leadership continues today, and not only in Fritz Lab, for Lehigh is also home to a National Science Foundation–funded Engineering Research Center that has extended the structural-testing capabilities of the university. The testing lab of the Advanced Technology for Large Structural Systems (ATLSS) Center, established in 1986, can accommodate scale- and full-size structures on a test floor measuring 40 by 102 feet, with fixed reaction walls up to 50 feet high encircling three of the test-floor corners. This structure allows the application of multidirectional forces and motions on varied structures under a wide range of load conditions.

Today, the five-million-pound BLH testing machine continues to be utilized on a regular, near-daily basis, as does other equipment at Fritz. In 1991, the American Society of Civil Engineers designated the original building as a civil engineering landmark, and on the fiftieth anniversary of the lab’s expansion, the University Libraries Special Collections opened an exhibit curated by Ilhan Citak and Eleanor Nothelfer.1

Coda

Many a story opens with a bang; this one concludes with a foundation-shaking, near-million-pound cacophony. As a follow-up to the research for this cover essay, I was invited to witness a test on the BLH machine. My observed test was of one of several suspender cables from the Throgs Neck suspension bridge (opened in 1961) which were being checked for their tensile strength after nearly fifty years. Although the actual test ran only about fifteen minutes once tension began to be applied to the sample cable, the setup work prior to the test was equally interesting and in many ways far more revealing. Arriving at Fritz Lab just after a previous cable test, I was initially disappointed that I had missed the “action”; however, it quickly became evident to me that I had come at the perfect time, as the Fritz crew began to disassemble the previous test setup and start on the next. For approximately the next three hours, I had a fascinating firsthand lesson.

The suspender cable is a two-and-one-quarter-inch, seven-strand, galvanized wire rope, with each strand consisting of perhaps fifty individual wires. It is rated at 450,000 pounds. The suspender is in effect doubled as it runs over the top of the main suspension cable, through a sheave, and is then anchored to the deck in two locations with button sockets. There are two places where such a cable is likely to fail—at the base around the socket where water, salt, oils, and other corrosive elements attack the wire, and at the tangent point where the cable begins to go over the sheave. Because of the way in which the socket is attached to the cable and because of the design of the BLH machine, the test for the socket assembly must be done on the older Riehle machine, which can grasp the socket in a manner that better simulates the actual bridge deck connection. However, for the sheave bend, the BLH machine can be utilized. The sample suspender cable proves too long for even the BLH machine, so for the test it is shortened, and new simulated socket attachments are fabricated as close as possible to the actual connections. The cable is first mounted over what, in effect, is a pulley-like device made to simulate as closely as possible the diameter and width of the bridge sheave itself. Once doubled over the pulley, which is attached to the top crosshead via a 6,200-pound connector, the two ends of the cable are bolted into a steel plate via their newly fabricated sockets, which, in turn, are attached to the lower crosshead.

Everything about this machine is big and heavy. As a result, almost nothing is moved by hand, but by the twenty-ton overhead crane or by a smaller chain lift on the machine itself. Safety is also paramount—and with good reason, as attested by patched walls and lab windows that have been replaced due to flying objects from past tests. But just before the massive steel safety shields are hoisted into place, we are allowed to ride up the BLH elevator to double-check and photograph the cable, now in place on the machine. Approximately three stories up and an arm’s length away from the cable, the testing machine’s scale appears far different than it does from the floor—more immediate, still massive, but somehow less overwhelming. Satisfied that the sample is appropriately in place in a manner that fully simulates the actual bridge situation, the consulting engineer from the company hired to analyze the cables and who has arranged for the test nods his readiness.

Back on the floor, safely ensconced in a position behind the lab foreman who initiates the test at the machine’s console and slowly applies tension to the cable, we watch the digital load readout move upward in 1,000-pound increments. Because the cable is doubled, yet not exactly double the rated strength since it is still a single piece, I am told the breaking point might be expected to occur at approximately 1.8 times the 450,000-pound rating. For about fifteen minutes the tension increases until we move past the point of double the rating—900,000. Now the tension really increases, and not just in the cable, as we all peer anxiously at the readout. At 972,000 pounds the first wire pings: the cable is starting to break apart. Then another ping and another, the foreman counting them off one by one. At 978,000 everything lets go at once, and tremendous energy is dispersed in a single moment, pulsing through the floor of the lab and resounding in our ears. I jump more than the seasoned observers, I am sure, even though I know it is coming. Then sudden relaxation and smiles all around—it is a good test. The wire has failed as expected, perhaps even at a tension point higher than anticipated. From the consulting engineer’s perspective this is a positive indication of the health of the wire, at least in this section of the cable. The lab manager, foreman, and team are pleased, as their test design and setup have gone off without a hitch.

I am left, if not quite breathless, then certainly impressed by my firsthand observation of the actual operation of a machine that I have only seen in static grandeur in the past. Even as I thank everyone and turn to leave to return to my office, the lab crew begins its work of tearing down this test in order to set up the next day’s work—a similar set of tests on suspender cables from the Walt Whitman Bridge.

1 Many images of John Fritz, the original and the new laboratories, and the testing equipment in them can be viewed at http://cf.lehigh.edu/projects/exhibits.asp?id=5 (accessed 14 January 2009).

Stephen Cutcliffe is a member of the Department of History at Lehigh University and routinely includes a stop at Fritz Lab whenever he offers a campus tour to a visiting SHOT member. He would like to thank Robert C. Post for suggesting the idea for the essay and for reviewing an earlier draft, and Ilhan Citak, Eleanor Nothelfer, Stuart Rankin of Ammann and Whitney Consulting Engineers, and Alan W. Pense, Lehigh professor emeritus of materials science and a frequent user of the BLH machine, for their assistance with the preparation of this essay. He would also like to thank Frank Stokes, manager; Gene Matlock, foreman; Robin Hendricks, staff engineer; and Shaun Keggan and Joe Timar, lab technicians, for their time, advice, and generous introduction to their testing procedures.

Copyright© 2009, the Society for the History of Technology

Filed under: Vol. 50 No. 2 (April 2009)