Proceedings of the Third International Congress on Construction History, Cottbus, May 2009
Charles C. Sunderland and the Diffusion of Prestressing Technologies in
the Americas
Dario A. Gasparini
Case Western Reserve University, Cleveland, U.S.A.
ABSTRACT: Charles C. Sunderland was employed by the John A. Roebling’s Sons Company for over fifty years,
from 1901 to 1952. He was Chief Engineer for Roebling for the construction of the George Washington Bridge.
He was appointed Chief Bridge Engineer of the newly-formed Bridge Division in 1929 and served in that capacity until retirement. Sunderland advanced fabrication and processing technology for steel wire, wire rope, and
wire strand. He developed new structural designs including prestressed cable truss bridges and posttensioned
concrete box bridges. Research initiated by Sunderland developed core technologies for the prestressed concrete industry in the U.S. He sustained Roebling’s vitality in bridge construction for the entire first half of the 20th
century.
INTRODUCTION
In a paper on the history of prestressed concrete in the U.S., Charles Zollman writes: “It is understandable that
the great Charles C. Sunderland …… would follow the example set by the Roeblings” (Zollman 1980). In an article describing an innovative steel cable truss bridge, Blair Birdsall writes: “The main features of the superstructure design were conceived and developed by the late C.C. Sunderland… the El Salvador bridge is a memorial to his vision and genius” (Birdsall 1954). In context of his collaboration with Sunderland, the consulting
engineer L. Coff (1951) remarks on “the genius of the man responsible for the cables of the longest spans in the
world.” Such effusive praise from one’s peers can only spring from a deep admiration and respect for the
character and principles of an individual. And it is primarily such traits that should be known and communicated to future engineers. However, the objective herein is more modest; it is to describe some of Sunderland’s principal engineering accomplishments and lasting influences.
Charles Cecil Sunderland was born in the District of Northowram, in the County of York, England, on 24 October 1881. The date of his immigration to the U.S. and his education are unknown to this author. On 15 October
1901 Sunderland was hired as a draftsman by John A. Roebling’s Sons Company (JARSCO) of Trenton, NJ. He
remained at JARSCO for his entire career: fifty years and seven months of continuous service. His tenure at
JARSCO spanned the golden age of American suspension bridge development and witnessed the emergence of prestressed concrete as an alternate construction material. During his tenure, JARSCO operated
synergistic materials-technology and structural research laboratories. These laboratories produced innovative
high-strength steel wire rope and strand products, new anchorages, and new structural systems. JARSCO and
Sunderland made direct, significant advancements in the erection of suspension bridges, in prestressed steel
bridge technology, and in prestressed concrete bridge technology. Sunderland was pivotal in maintaining the
vitality and creativity of JARSCO in the first half of the 20th century; under his leadership, the products that
JARSCO developed “became synonymous with high quality” (Zollman 1980).
Proceedings of the Third International Congress on Construction History, May 2009
CHIEF ENGINEER FOR ROEBLING ON THE GEORGE WASHINGTON BRIDGE
By 1910, Sunderland was the engineer-in-charge of the Wire Rope, Bridge, and Tramway Departments at
JARSCO, contributing to rope and strand making technology. On 4 November 1927, JARSCO was awarded
the largest single contract by the Port of New York Authority for the fabrication and erection of the cables,
suspenders, and anchorage steel for the new George Washington (GW) Bridge. Charles C. Sunderland was
appointed Chief Engineer for JARSCO for the execution of the contract. The first problems that arose from the
unprecedented scale of the GW Bridge concerned the accurate fabrication of very long wire ropes and accurate prediction of their tension-elongation behavior. No rope-making machine that could form and “compact” a rope under the envisioned tensions existed. When the working load on a rope exceeded the tension
used during manufacture, the rope compacted further and inelastic axial deformation occurred. Sunderland
decided to prestretch (Sunderland used the word prestress) all ropes with loads that exceeded their design
working loads. JARSCO built prestretching facilities at their Kinkora plant, adjacent to the town of Roebling, NJ.
Their operations are described in an Engineering News-Record article by Sunderland (1930). Sunderland’s innovation of prestretching wire rope was also applied to wire strand. This had an immediate, important influence on the design of medium-span suspension bridges. David Steinman used galvanized, prestretched, presocketed, Roebling wire strands for his Grand Mere, Quebec, suspension bridge (Steinman 1929). With Sunderland as Chief Engineer, JARSCO completed the four main cables of the GW Bridge thirteen months ahead of
contract requirements (Schuyler 1931). On 3 February 1932, Othmar Ammann, the great Chief Engineer for the
Port of New York Authority, wrote Sunderland a letter with characteristic understatement:
I take this occasion to express to you, on behalf of the Engineering Staff of the Port Authority, its appreciation of the excellent and efficient manner in which you have carried out this unusual and important work,
and in particular, also the cooperation which you and your Engineering Staff have manifested throughout
the period of construction. (Ammann 1932)
JARSCO won additional contracts for other major suspension bridges during the construction of the GW
Bridge. Because of this work, JARSCO formed a new Bridge Division in 1929 and Sunderland was named Chief
Bridge Engineer.
RESPONSE TO THE COLLAPSE OF THE TACOMA NARROWS BRIDGE
The collapse of the Tacoma Narrows Bridge on 7 November 1940 prompted engineers to re-examine suspension bridge forms other than the conventional deck-stiffened type. In general, designers perceived that the
principal need was to “increase stiffness and damping.” George Maney, a professor at Northwestern University, proposed prestressed diagonals, essentially turning the conventional suspension bridge into a truss, a concept that he later patented (Maney 1941). The staff of Modjeski and Masters (Suspension bridges and wind
1941) suggested inclined hangers, a very similar concept. They claimed that in addition to providing greater
stiffness, inclined hangers also produced higher damping. However, their observations were made on the basis
of the response of a small, 3.5m long, model, on which the frictional contributions to damping are generally
greater than on an actual prototype.
Sunderland’s response also focused on studies of truss-like systems. However, JARSCO’s fabrication and engineering expertise and laboratory facilities enabled implementation of concepts into actual designs. Sollenberger (1954) states that two general types of cable systems were conceptualized and studied. One used two
suspension cables with different sags, in a “festoon” arrangement, with struts and diagonal bracing between
the cables. The other consisted of two cables of opposite curvature, with diagonal bracing between them. The
first system was implemented in a pedestrian bridge built in 1943 between two buildings at the JARSCO Trenton
plant. JARSCO also built a multi-span pedestrian suspension bridge of this type over the Delaware River at
Lumberville, PA (Suspension footbridge 1948). Its suspension system is a combination of braced panels, diagonal stays, and pretensioned longitudinal cables. Although the design may be said to “lack clarity,” what is significant is that there is no stiffening girder. Prestressing is used to provide stiffness and to preclude cable slackness.
The culmination of Sunderland’s development of prestressed steel cable bridges was the great San Marcos
Bridge in El Salvador, completed in October 1952, three months after Sunderland’s death. JARSCO successfully
bid for the contract in March 1948, assuming responsibility for design, fabrication and erection.
Figure 1: San Marcos prestressed cable bridge
Proceedings of the Third International Congress on Construction History, May 2009
Fig. 1 shows the multi-span, “all-cable” bridge. The design was based on measurements on a 1/20-scale physical model instrumented with strain gauges. Birdsall (1953, 1954) and Sollenberger (1954) describe the engineering aspects of the bridge. The “open” feature of the chords followed Sunderland’s philosophy of corrosion protection by galvanizing and accessibility. All strand and rope were prestretched, precut, and pre-socketed by
JARSCO and shipped to the site. The pre-socketed wire strand simplified the anchorages. The principal engineering design feature of the bridge was that a “cable truss” was achieved by pretensioning the lower chord,
which had a curvature opposite to that of the top chord. The lower chord tension was anchored into the concrete roadway, thus producing a 670m long prestressed concrete deck. Blair Birdsall is direct about giving
credit for the conceptual design of the bridge:
The main features of the superstructure design were conceived and developed by the late C. C. Sunderland, former chief engineer of the Bridge Division. The El
Salvador Bridge is a memorial to his vision and
genius. (Birdsall 1953)
The San Marcos Bridge received extensive professional and popular publicity. However, it did not redirect
long-span suspension bridge design away from the conventional deck-stiffened form. A reason for this is that
the bridge was in fact a product of the unique engineering, fabrication, and construction expertise of the
JARSCO Bridge Division, led by Charles Sunderland. No other design firm in the world was able to design and
construct such a bridge, much less advance the concept.
RESEARCH AND DEVELOPMENT IN PRESTRESSED CONCRETE TECHNOLOGIES
American engineers became aware of prestressed concrete and the seminal contributions of Freyssinet In the
1930’s (Rosov 1938). However, prestressing of concrete was practiced in the U.S. since about 1931 for the construction of storage tanks (Dobell 1951; Crom 1952). Sunderland’s enthusiasm for prestressed concrete was
probably kindled by L. Coff, a consulting engineer from New York knowledgeable about European advancements and designs. Sunderland foresaw that prestressed concrete was a promising future market for JARSCO
high strength wire, strand, and rope products. In 1944, in the midst of development work on the prestressed
steel cable truss, Sunderland initiated research on prestressed concrete at JARSCO. One of the principal engineering design choices relative to prestressed concrete is whether to use unbonded, end-anchored, posttensioned tendons or to rely on bond to affect prestress. With the variety of galvanized strand and rope products
already produced by JARSCO for steel bridges and in accord with his “galvanized, open, and accessible” philosophy for corrosion protection, Sunderland focused early research on unbonded, posttensioned systems. As
for prestressed steel systems, JARSCO research and development was comprehensive; it included model studies, development of new products, and actual design applications. By 1950, JARSCO had completed six years
of innovative studies related to prestressed concrete (Sunderland 1950; Birdsall c1950).
Figure 2: One-tenth scale model of posttensioned bridge
One of the first studies performed at JARSCO involved the bridge model shown in Fig. 2, fabricated and tested
between 1944 and 1947. It is a five-segment, posttensioned, 6.1m (20ft) long beam designed as a 1/10 scale
model of a prototype bridge. It is posttensioned with ten exposed 8mm (5/16”) diameter strands in a parabolic
profile formed by saddles on webs of different depths. The beam was first tested with a scaled load equivalent to four times a normal bridge loading. Strain gauges were used to acquire data. After removal of the load
the beam returned to its original position, with no measurable permanent displacement. A load equivalent to
twice a normal bridge loading was then permanently applied. No measurable increase in vertical displacement occurred over a three-year period. It is probable that the design was developed by L. Coff, who collaborated with Sunderland and JARSCO as a consulting engineer, although exposed parabolic tendons within
a channel or box beam is a design concept used by Dischinger as early as 1937 (Komendant 1952).
To study the feasibility of using prestressed concrete for airport pavements, JARSCO prestressed a 29.3mx43.9m
(96ftx144ft) section of floor in their Cicero, Illinois warehouse in October, 1946 (Jointless prestressed 1949).
JARSCO also designed and fabricated precast, posttensioned ribbed slabs for the deck of their Lumberville
pedestrian bridge (Suspension footbridge 1948). The slabs were prestressed transversely with 12.7mm (½”) di-
Proceedings of the Third International Congress on Construction History, May 2009
ameter rods wrapped in waxed paper tubes and threaded at their ends. The 200 individual deck sections
were subsequently posttensioned longitudinally using 14.3mm (9/16”) diameter bridge strand.
The above studies and designs show the JARSCO-Sunderland direction: posttensioned systems using galvanized, prestretched, unbonded bridge strand and compact swaged anchorages. JARSCO posttensioning systems were used by Ross H. Bryan to design and build his posttensioned concrete block beams for the Fayetteville stadium and for his Madison County, TN, road bridge (Bridge built of blocks 1951; Bryan 1951; Bryan 1979).
The same JARSCO technology was also used by C. L. Johnson to build his John R. Road Bridge in Oakland
County, MI (Johnson 1951).
Hot galvanized, prestretched, pre-socketed bridge strand and the posttensioning systems developed under
Sunderland’s leadership were not appropriate for factory-produced components prestressed by bond between the steel and concrete. More suitable prestressing steel products were needed; however, several important issues had to be resolved. The cold-drawing of wire produced a fibrous microstructure in the steel that not
only resulted in very high strengths but also had high residual stresses. These residual stresses decreased the
“proportional limit,” that is, the stress at which the tangent modulus began to decrease, as well as the stress
levels at which creep in the steel became significant. The hot galvanizing used by JARSCO reduced these residual stresses and produced “stress-relieved” wire and strand. The stress-relieved products maintained the initial modulus of elasticity to higher stresses and essentially did not creep at stress levels used in prestressing concrete. The basic need relative to bonded prestressed concrete products was for high-strength, ungalvanized
(for greater bond), stress-relieved, large-diameter wire. Zollman (1978) states that Sunderland developed the
stress-relieving process for ungalvanized wire in 1949. It was the wire that was to be supplied by JARSCO for the
Walnut Lane Bridge (Godfrey 1951). The scale of typical civil engineering components, however, required
tendon areas greater than those of wires that could be drawn. Therefore an additional challenge was to develop high-strength, ungalvanized, stress-relieved strand, able to prestress concrete through bond. Bryan
(1979) directly states that: “This tendon was developed by Charles Sunderland of the Roebling Company.”
Zollman, however, provides a more complex scenario. In his discussion of the development of prestressed box
girders by the Concrete Products Company of America, he notes that Walter O. Everling, Director of Research
for American Steel and Wire Company of Cleveland, “came up with the stranded seven wire unit” (Zollman
1978). B. J. Baskin, Chief Engineer for the Concrete Products Company of America, also recounts that: “After
making several tests of different strand construction of ¼-inch diameter cable the 7-wire strand of extra
strength was adopted” (Baskin 1951). Of course JARSCO had used 7-wire strand (unbonded and galvanized)
in 1946 for prestressing the Chicago warehouse floor. Regarding the stress-relieving of strand, Zollman (1980)
notes that Howard J. Godfrey, Assistant Chief Development Engineer at JARSCO, “developed the successful
procedure: making the strand from as-drawn wires and then stress-relieving the strand.”
Under Sunderland’s leadership, JARSCO developed a posttensioning system characterized by galvanized, unbonded, pre-stretched wire strand tendons with compact swaged anchorages. To serve the fabrication of
prestressed components, Sunderland developed a process for stress-relieving ungalvanized wire and his
JARSCO colleague, H. J. Godfrey, developed a process for stress-relieving ungalvanized seven-wire strand. The
stress-relieved seven-wire strand remains an industry standard to this day. JARSCO developed the essential
core technology that enabled the emergence of the prestressed concrete industry in the U.S. after 1950.
THE ROEBLING PROPOSAL FOR THE WALNUT LANE BRIDGE
The Walnut Lane Bridge in Philadelphia is widely known as the first prestressed concrete bridge in the U.S.,
even though Ross Bryan completed his small, rural, posttensioned concrete block bridge first, on 28 October
1950 (Bryan 1951). The test performed in October 1949 on one of the girders of the Walnut Lane Bridge (Anderson 1979) generated extensive professional publicity and construction of the bridge provided impetus for the
prestressed concrete industry. The history of the project is recounted by Schofield (1948), Baxter (1951) and by
Zollman (1978, 1978a, 1980). How did the City of Philadelphia decide to build a prestressed concrete bridge?
E. R. Schofield, Principal Assistant Engineer for the Bureau of Engineering, Surveys and Zoning in Philadelphia,
vaguely states: “About this time the writer made the acquaintance of L. Coff, consulting engineer for the John
A. Roebling’s Sons Co. and Prof. Gustave Magnel of Ghent University, Belgium” (Schofield 1948). Samuel S. Baxter, Chief Engineer of the Bureau, states: “Among those with whom Mr. Schofield talked were L. Coff, Consulting Engineer of New York, and representatives of the Preload Corporation. Contacts were also made with Professor Gustave Magnel in Belgium” (Baxter 1951).
On the basis of Schofield’s and Baxter’s statements, Coff’s claim that: “I was one of the originators of the
prestressed concrete scheme for the Walnut Lane Bridge” (Coff 1952) has strong credibility. Zollman (1978)
helps to clarify the actual chronology and set of events. He quotes from a remarkable letter written by
Schofield on 5 June 1948 to Sunderland:
Since I saw you last April several things have happened to our Walnut Lane Bridge. The Pre-Load Co. (sic)
who are building some digestion tanks for us requested permission to sudy the problem. Although I did not
like the situation, I could hardly refuse, my position being what it is. At the time I was very enthusiastic about
Mr. Coff’s plan but did not like the probable erection difficulties….In studying the proposed Walnut LaneBridge, the Preload Corporation went to Europe and hire Professor Magnel. He proposed a prestressed
girder bridge similar to those which had been built in Europe. (Zollman 1978)
Proceedings of the Third International Congress on Construction History, May 2009
Schofield’s letter means that a prestressed concrete design had been proposed to Schofield before the Magnel design. This earlier design, which Coff says “was presented by the Bridge Department of the John A. Roebling’s Sons Co” (Coff 1952), is illustrated and discussed by Komendant (1952).
Figure 3: Roebling-Coff Walnut Lane Bridge Proposal
Fig. 3 shows the JARSCO/Coff/Sunderland design. The design consists of three haunched box girders. Each box
girder is posttensioned by 11- 63.5mm (2½”) diameter galvanized, prestretched bridge ropes with compact
swaged end anchorages. That is, the design follows Sunderland’s philosophy regarding corrosion protection.
However, the Bureau of Engineering, Surveys and Zoning of Philadelphia chose Magnel’s European design
rather than an American posttensioned, unbonded system. Zollman recounts Sunderland’s reaction to the decision:
Although Sunderland must have been extremely disappointed when Roebling’s design was rejected, he
calmly and gracefully accepted the rejection, refusing to make an issue of the decision even when urged
to do so. Instead, he said: Well, we shall now proceed with the manufacture of a cold drawn wire with qualities second to none, and that is precisely what he did. (Zollman 1980)
A stress-relieved, 7mm (0.276”) diameter high-strength cold drawn wire was the outcome of Sunderland’s
commitment. Magnel’s Walnut Lane Bridge was the first structure in the world to use such high quality wires
developed and produced by JARSCO.
DIFFUSION OF PRESTRESSING TECHNOLOGIES IN THE AMERICAS
In 1949, JARSCO completed a small suspension bridge over the Rio Paz between Guatemala and El Salvador.
It is a remarkable example of the prestressing technologies developed at JARSCO under Sunderland’s leadership (Reeve 1950; Birdsall c1950). The bridge embodies JARSCO’s advanced engineering capabilities in both
steel and concrete, not only in fabrication and construction, but also in design. The suspension bridge has an
overall length of 122.6m, with a main span of 64m. The main cables consist of six prestretched, galvanized, presocketed bridge strand in an open arrangement.
Figure 4: Deck of the Rio Paz Bridge
Proceedings of the Third International Congress on Construction History, May 2009
The bridge deck is shown in Fig. 4. It consists of precast box beam units, 30.5cm (12”) deep, 53.3cm (21”) wide
and 6.6m (21’-7½”) long. The units are posttensioned using two 15.9mm (5/8”) diameter galvanized bridge
strands on a parabolic curve, anchored using compact swaged fittings. The (224) box beams are strung together and posttensioned using eight 31.74mm (1¼”) diameter, galvanized, prestretched bridge ropes. The
deck is an innovative design, developed independently by JARSCO.
Sunderland and Coff were able to realize their vision of galvanized, exposed-tendon, post-tensioned box
girder bridges; however, not in the United States but rather in Cuba. In collaboration with the Comisión De Fomento Nacional De Cuba under the supervision of Luis Saenz, the JARSCO concepts were incorporated in the
design of the Cañas River Bridge shown in Fig. 5. The bridge was posttensioned with a total of 112 – 25.4mm
(1”) diameter galvanized wire strands with swaged anchorages. The strands were coated with bituminous
paint for additional corrosion protection.
Figure 5: Canas River Bridge
The Cañas River Bridge was completed in December 1952, unfortunately a few months after Sunderland’s
death. By 1956 four other similar box girder bridges were built in Cuba (Preston 1956; Zollman 1980). The
Agabama Bridge near Trinidad was completed in 1953. The Arimao Bridge near Cienfuegos was completed in
1954. The Cuyaguateje River Bridge near Pinar Del Rio, shown in Fig. 6, was completed in 1954. It has a remarkable central span of 91m (298’-6”).
Figure 6: Cuyaguateje River Bridge
It was posttensioned with 28 – 43mm (1-11/16”) diameter galvanized bridge strand, again coated with bituminous paint for additional corrosion protection. A final posttensioned design, the Felipe Pazos Bridge, was completed in 1956. Continuous, unbonded, galvanized, posttensioning tendons enclosed within box girders distinguish these designs from the standard simply-supported I-beam or precast, prestressed-box-girder bridges
commonly used in the U.S. in the 1950’s. As of October 2008, all but one (the Felipe Pazos) of the posttensioned
concrete box girder bridges built by JARSCO in Cuba are extant and in service (Gonzalez 2008). The
Agabama and Arimao bridges have the original JARSCO tendons. The Cañas and Cuyaguateje bridges have
had tendons replaced (Gonzalez 2008). The durability of the Cuban posttensioned box girder bridges vindicates Sunderland’s philosophy of corrosion protection.
THE LEGACY OF CHARLES C. SUNDERLAND
Charles Sunderland advanced fabrication and processing technology for steel wire, wire rope, and wire
strand. He developed innovative techniques for prefabrication of shorter-span suspension bridges. Sunderland
developed new structural designs, including prestressed cable truss bridges and posttensioned concrete box
bridges. Research initiated by Sunderland developed core technologies for the prestressed concrete industry.
Roebling engineers provided invaluable leadership within the nascent prestressed concrete industry (Zollman
Proceedings of the Third International Congress on Construction History, May 2009
1980). Charles Sunderland served the John A. Roebling’s Sons Company for 50 years and 7 months. He sustained Roebling’s vitality in bridge construction for the entire first half of the 20th century. He retired on 15 May
1952 and died two-and-one-half months later on 31 July 1952.
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ACKNOWLEDGMENTS
The following individuals provided invaluable help with the research: Tom Spoth, Vice President of the Parsons
Corp. NY, James Birdsall, Wendy Nardi at the Trenton Public Library, William Barrow at Cleveland State University, Jay Trask at the Bessemer Historical Society, Al King at Rutgers University, Ellen Lempera of the Cicero Public Library, Donald Sayenga, Stephen Buonopane, Eberhard Pelke, Frank Rausche, Eric DeLony, Justin Spivey,
Tom Peters, Charles Birnstiel, Alejandro Maldonado, and Angel Martinez Gonzalez. Linda Gasparini assisted
with the library research.