The story of prestressed concrete from 1930 to 1945: A step towards the European Union The early h story of prestressed concrete is almost entirely related to rearmament and the war effort beginning in the early 1930s with the German preparations for the Second World War. For that reason, there are few records of the development of this technique: everything was top secret. We were fortunate to find a number of people who had lived at that time and who had a knowledge of the events in question. They provided us with a great deal of oral information, but in the meantime, alJ of them have died. T he story is somewhat bizarre. The underlying idea had been around for a long time, but it was Eugene Freyssinet who carne up with the invention that alJowed the idea to be put into practice. The French themselves sh ow ed no great interest in the invention. The Germans, on the other hand, wished to save steel for war (a war they were also to wage against France, of course), and the German company Wayss & F rey ta g o bta ine d a lic en ce fram Freyssinet -only to use his system a lm os t e xc lu siv ely for the cons ruction of bunkers. Initially, the chief negotiator for Wayss & Freytag was Professor Karl W. Mautner, but since he was a Jew by birth, the Nazis soon removed him fr m all his offices. In the pogrom of 9 November 938, he was arrested and detained in Buchenwald concentration camp for six weeks. Sir Alan Harri -deputy head of P.C.c., the world' s first prestressed concrete firm, and later a partner of Harris and Sutherland engineers- Bernard Marrey Jupp Grote informed us that the London firm of Mouchel Engeneers invested quite a lot of money and obtained the help of the secret se rvic es of several go ve rnm en ts to free Karl Mautner and ge him and his wife out of Germany in the summer of 1939. Probably the most important content of M autner's luggage were the records of prestressing trials carried out in France and Germany. These events led to the triumphant advance of this tec hn olo gy in Britain. T he re, too, it was initially u sed alm ost exclusively for the construction of bunkers and for girders in tempo ary bridge construction in te nd ed to repair eventual w ar d am age . There is good reason to believe that alJ the parties involved in these developments fulfilled their contractual obligations. Freyssinet provided the know-how, and the recipient companie correctly paid their licence fees. For at least one German bunker, concrete anchorage cones for the sheaves of tensioning wires were delivered from France in 1943-44, together with the appropriate jacking devices presumably. As a result, a collaboration be tw een European b uild in g c on trac to rs w as p os sible after 1945 without disputes about money and fees. of the European Coal and Steel Community, which was formally established in 1952 and which may be seen as one of the predecessors of the European Union. All's well that ends well, one might sayo But there is also a tragic side to this story: alone on one German Proceedings of the First International Congress on Construction History, Madrid, 20th-24th January 2003, ed. S. Huerta, Madrid: I. Juan de Herrera, SEdHC, ETSAM, A. E. Benvenuto, COAM, F. Dragados, 2003.
The story of prestressed concrete from 1930 to 1945:
A step towards the European Union
The early history of prestressed concrete is almost
entirely related to rearmament and the war effort,
beginning in the early 1930s with the German
preparations for the Second World War. For that
reason, there are few records of the development of
this technique: everything was top secret. W e were
fortunate to find a number of people who had lived at
that time and who had a knowledge of the events in
question. They provided us with a great de a l of oral
information, but in the meantime, alJ of them have
died.
T he story is som ew hat bizarre. T he underlying idea
had been around for a long time, but it was Eugene
Freyssinet who carne up with the invention that
alJowed the idea to be put into practice. The French
th em selve s sh ow ed n o gre at in teres t in th e in ve ntio n.
The Germ ans, on the other hand, wished to save steel
for w ar (a w ar they were al so to wage against France,
of course), and the German company Wayss &
F rey ta g o bta ine d a lic en ce fram Freyssinet -only to
use his sy stem a lm os t e xc lu siv ely for th e co nstru ctio n
o f bunke rs .
Initially, the chief negotiator for W ayss & Freytag
was Professor Karl W . Mautner, but since he was aJew by birth, the Nazis soon removed him from all his
offices. In the pogrom of 9 November 1938, he was
arrested and detained in B uchenw ald concentration
cam p for six w eeks.
Sir A lan Harris -deputy head of P.C.c., the
world' s first prestressed concrete firm, and later a
partner of Harris and Sutherland engineers-
Bern ard Ma rre y
Jupp G rote
informed us that the London firm of Mouchel
E ngeneers invested quite a lot of m oney and obtained
the he lp of the sec ret se rvic es o f se ve ral go ve rnm en ts
to free Karl Mautner and get him and his wife out of
Germany in the summer of 1939. Probably the most
important contents of M autner's luggage were the
records of prestressing trials carried out in France and
Germany.
These events led to the triumphant advance of this
tec hn olo gy in B ritain. T he re, to o, it w as in itially u sed
alm ost exclusively for the construction of bunkers
and for girders in temporary bridge construction
in te nd ed to rep air ev entu al w ar d am age .
There is good reason to believe that alJ the parties
involved in these developments fulfilled their
contractual obligations. Freyssinet provided the
know-how, and the recipient companies correctly
paid their licence fees. For at least one German
bunker, concrete anchorage cones for the sheaves of
tensioning wires were delivered from France in
1943-44, together w ith the appropriate jacking
devices presumably. As a result, a collaboration
be tw een E urop ea n b uild in g c on trac to rs w as p os sible
after 1945 without disputes about money and fees.T hes e p os t-w ar de ve lo pm en ts para lJel the em erge nc e
of the European Coal and Steel Community, which
was formally established in 1952 and which may be
seen as one of the predecessors of the European
Union.
All's well that ends well, one might sayo But there
is also a tragic side to this story: alone on one G erm an
Proceedings of the First International Congress on Construction History, Madrid, 20th-24th January 2003,ed. S. Huerta, Madrid: I. Juan de Herrera, SEdHC, ETSAM, A. E. Benvenuto, COAM, F. Dragados, 2003.
Th e sto ry of p re stre ssed conc re te from 193 0 to 19 45: A step tow ard s the E urope an U n ion 1371
In 1933, w ith a courage -or foolhardiness- born
of desperation, F reyssinet aeeepted the assignm ent ofsaving the transatlantie quay in L eH avre. T he projeet
was beset with risks. The strueture was in danger ofcollapsing even before being eom pleted beeause it
had been overlooked that there was silt beneath thegravel foundations, Figure 3. The m ain elem ents of
Freyssinet's solution w ere three large prestressedeonerete girders, which he inserted beneath thestrueture, underpinning them with additionaJ piJes,Figure 4. A llegedly, these girders still form the m ain
load-bearing members of the new term inal of 1954
w hie h re plae ed th e o ld stru ctu re af ter it w as d estro yedby A llied bom bing in 1944.
F ig ur e 3Cross -sec ti on through the At lan ti c t ermina l a t LeHav re.
Figure 4
Prestressing system Baur-Leonhardt, similar to that
conceived by Freyssinet for LeH avre: The beam s w ere post-
tensioned by means of wires looped around saddle pieces
w hich w ere ja cke d outw ards
The successful rehabilitation of the quay inL eH avre m arked a breakthrough for Freyssinet. Theleading engineers of his day pilgrim aged to the site -
am ong them , Edm e Cam penon, who subsequentlybecame Freyssinet's lifelong partner in thec on stru ctio n fir m C ampe no n B ern ar d.
F ig ur e 5Edme Campenon ( Je ft ) a n d Eugene F re ys si ne t ( ri gh t)
In 1936-37, the Campenon Bernard companyerected the w orld's first prestressed concrete bridge
in Oued Fodda, A lgeria, Figure 6
It consists of 4 bays with a total of 12 precastgirders that span a distance of 20 m etres. The bridge
still stand s today. The idea of prefabricating theelements was al so Freyssinet's. For some timeafterw ards, though, there w ere no further contracts to
follow this up.
Freyssinet' s application for a patent in G erm any
led initially to the usual objections and formaldisputes. In many quarters, his technique wasregarded m erely as an extensjon of existing ideas. N o
record survives of the opposition that carne from
Dyckerhoff & Widmann. Franz Dischinger andU lrich Finsterw alder, on the other hand, genuinelysought a m eans of realizing prestressed concrete that
would not conflict w ith Freyssinet's patent. Bothengineers set their sights on reinforced concrete
g ird ers w ith tru sse d te nd on s on th e u nd ers id e.Only one bridge was ever bui]t to D ischinger's
1 9 3 4 patent -the A dolf H itler Bridge ayer the M ulde
F igu re 6The f ir st p re st re ss ed b ri dg e, bu il t 1 936 /37 , Oued Fodda (A lg er ia ) 1999
in A ue, Saxony, in 1936-37. The stee1 tension chords(G erm an stee1 qua1ity St 52) w ere designed to allow
for post -tensioning at a 1ater date to com pensate forcreep and sh rin kage. P ost-ten sion in g w as carried o ut
repeatedJy after 195°, but the effect aJways
disapp eared after a few y ears, an d finally, in 1 99 2, theb rid ge h ad to b e d em olish ed .
U1rich Finsterwa1der applied for a patent for a
v ariatio n o n th e sy ste m o f rein fo rce d c on crete g ird erstrussed on the underside: he deve10ped a «self-activatin g pretensio ning » system th at ex p1 0ited th e
ch an ge o f fo rm o f th e g ird er resu 1tin g from its dead
weig ht, F ig ur e 7 .
. - : r. .
LI
I ~. L - - - 1 I
F ig ur e 7Finste rwalder ' s se lf-ac t iva t ing prest ress ing system.
Four structures w ere executed in accordance w ith
this patent. The first was a rural road bridge over the
autobahn near W iedenbrück. The bridge had to bedem oJished in 1997. The w ell-know n civil engineer
Fritz Leonhardt observed of this structure that atprecise1y the point where the greatest bending
m om en t o ccu rred , th ere w as n o p restressed con crete,on1y a tensioned steel (St 52) tendon and a hinged
joint.The bridge was followed by the trussed girders in
the roof structure over Tem pe1hof A irport in Berlin(1936-38) with a span of 32.5 m and stee1 tension
chords (St 52). This completely independentinterpretation of «prestressed concrete», w ithout ahinge in the m iddle of the span, has been refurbished
an d is still in go od co nd itio n to day .
The roof oyer the «Hall of the NationalCom munity» in W eim ar, built for H itler's N S Party,
consisted of identical trussed girders with a span ofroughly 50 m. The building, which was completed
long after the war by the East Germ an goyernment, is
r ath er ug ly , b ut s ti ll in g oo d condition.
The same trussed girders were used for the fourthstructure, the old airport in M unich, w here they had aspan of 80 m . The structure w as dem olished long ago,
T he story of prestressed concrete from 1930 to 1945: A step tow ards the European U nion 1373
Karl M autner, acting cm behalf of his com pany,Wayss & Freytag, seized the bull by the horns and
entered inta a licence agreem ent with Freyssinet in
1934. This agreement was evidently respectedthroughout the w ar and during the post-war years. In
various publications, W ayss & Freytag c1aimed
savings of 67 per cent of the norm al reinforcing steel
through the use of prestressed concrete according ta
Freyssinet' s patent. That w as not strictly accurate,however. What was really involved was thepro portio n of «p erm issible» stresses in the steel.
The company demonstrated the load-bearingcapacity of prestressed concrete girders w ith two
large-scale tesl elements. Karl Mautner was
Figure 8The girders for lhe bridge al Oelde (1938) were casI in
sections: The rear section is com plete, the central section is
hooded for steam heating, and on the right only the lower
flan ge h as b een casI. L ow er t1 an ge p restresse d w ith stra ig ht
wires of different 1ength, pre-tensioned and anchored on a
ste el p restre ssin g b ed . T he stirru ps w ere p restressed ag ain st
t he f re sh c on cr et e.
resp onsib le fo r con du cting th ese trials, bu t as a Jew , it
was no longer possible for him to perform his roleopenly in Germany. He signed documents simply
with his initial, «M». The results of these trials,however, were am ong the papers he took with him in
1939 w hen he fled to England.
In 19 38 , a first, sm all ru ral ro ad brid ge w as erectedw ith four girders, Figure 8, and a span of 32 mover
the autobahn near Oelde (Beckum). The design w asby Eugene Freyssinet him self, who had a mock-up
girder constructed in Paris for the instruction of
members of the W ayss & Freytag team. There weren o d raw in gs. T han ks to th e care of the lo cal au tho rity
responsible for this structure, the bridge near O elde(B eck um ) s till s ta nd s to day .
This was followed, before the war, by a quaystru ctu re an d a series of p recast p restressed con cretegirders for factory halls that were important for the
w ar effo rt. D urin g th e w ar y ea rs, p re stress ed c on cre tewas used almost exc1usively for bowstring roofgirders over bunkers for the German navy. W ith
spans of roughly 30 m, som e 150,000 metres of these
girders w ere produced in G erm any, the N etherlandsa nd No rw ay .
The largest structure, covering an area of roughly 5ha (12 acres), was a submarine factory in Farge,Bremen, in which U-boats were to be built in a
/¡fl.{}f r f J b p::::~
hU e
~--;--'.'~.,~~~! >
1'--
hg d
x' 7.~
1".
¡g¡j-~~-~- ---
¡j!lt
I-'-~
~- ~UJ/I
Figure 9
T yp es o f b ow strin g tru sse s fo r G erm an b un kers w ith straig ht
pre-tensioned wires anchored as shown in Figure 2 on a
co nvey or -belt system of th e k in d ad vocated b y H en ryFord. Three submarines a week were to be
m anufactured in this w ay. In view of the increasingeffectiveness of Allied bombs, plans were made to
increase the thickness of the bunker roof from 4.5 to
7 m. The load-bearing capacity of the prestressedconcrete girders w as inadequate for this, how ever.
Concrete anchorage cones invented in September
1939 by Freyssinet were therefore obtained fromCampenon Bemard in Paris for additional external
sh eav es o f p restre ssin g w ires.
n"vt~G I t M .a th -
1fJw,tu:S",m
Uwlr~':!mrn14 t ."&tlpln
~~'tJhat'l~r
1::;'
In alllik elih oo d, n eith er F re yssin et n or C am pe no nBernard collaborated with any great zeal with the
G erm ans. The situation was probably sim ilar to thatd escrib ed b y lean P aul Sartre: «Will I b e u ndersto odif I say that the occupation w as intolerable, yet at the
sam e tim e that w e coped quite com fortably w ith it?»The only three prestressed concrete bridges
realized in France during the war years w ere not builtby Campenon Bernard, but by Sainrapt & Brice, a
com pany th at collaborated closely w ith the G erm ans
and that w as able lO divert cem ent and steel destined
"-.-9)'C
-~~-" '.4W~"~
\ ¡ C,)~I(\
,2/1}
! ¡,! ,.'3~~2
¡ ! l. / "2/4
! .¡ ¡
I ::j~W~-;/i',,,, f
l / tO
"2Jf,
'";11.'''1.2,1 .n~;¡
Figure 10
The hangar in K arachi, 1942 and 1998. Prestressed girders m onolithic w ith roof shells on prestressed m ain beam s.
T he sto ry o f p restressed co ncrete fro m 1 93 0 to 1 94 5: A step to ward s th e E uro pean U nío n 1375
for the construction of the Atlantic Wall to otherpurposes.
F rey ssinet also to ok the o pp ortu nity to test h is new
ideas. In 1941-42, he built a bridge with a modest10.S-metre span in slab construction over a river inElbeuf near Rouen. It is the first post-tensioned cast
in-situ bridge. H e used his new system of sheaves ofprcstressing wires with concrete anchorage cones
being no longer straight but curved and coated w ith
bitumen to avoid bonding. In addition there werestraight transverse tendons of the same kind. In
1942-43, a sim ilar slab bridge with a 20-metre span
w as bu ilt o ver a riv er in L on gro y n ear E u-Ie-T rép ort.O n this occasion, post-tensioning w as applied step-by -step. B etw een 19 42 and 19 44 , a p recast foo tbrid ge
with spans of 30 and 31 m was constructed over therailway line near Lens. None of these three bridges
w as a c ru cia l tra nsp ort s tru ctu re o r o f an y s ig nifica nc efo r th e G erm an occup yin g po wers.In that respect, the first railway bridge in
prestressed concrete was presumably a different
m atter altogether. It w as built in 1943-44 over the rue
M iroir in Brussels by Gustave Magnel inco llabo ratio n w ith th e co nstru ction co mp an y B laton -A ub ert an d still ex ists to day . T he b rid ge w as c ertain ly
of interest to the G erm an m ilitary. In this structure,Magnel tested new , and again curved, multi-wire
ten do ns in flex ib le rectan gu lar du cts, sin ce he w as n otentirely satisfied w ith Freyssinet' s solution. A t that
tim e M agnel had no contact w ith the latter, how ever.M eanwhile, far removed from Europe, Robert
Shama, an Egyptian w ho had studied in France, used
Freyssinet's new tendons in spectacular form in am ilita ry a ircraft h an ga r b uilt in M ee ru t n orth o f D elh i.
Erected in 1940-41, it w as probably the first cast in-
situ stru cture to b e realized w ith curv ed tend on s, even
before the bridge at Elbeuf. The tendons passedthrough t1exible sheathings and were anchored by
m eans of those concrete anchorage cones inventedonly in 1939. A lthough C. G. Sexton announced this
building as if it were his own, Sir A lan Harris
believed Robert Shama to be the true author of the
scheme. The construction firm w as J. C. G amm on.According to information from the Aeronautical
In form ation S erv ice, D elhi, th e h an gar has since b eendemolished, but a sim ilar structure dating from
1942-43 in Karachi still exists and appears to be in agood state, Figure 10.
In G ermany, it w as p r o b a b l y not possible to use
cu rv ed p restre ssin g, sin ce F rey ssin et's G erm an p aten ts pe ci fi ed t he u se o f s tr ai gh t p re st re ss ing r ei nf or cemen t.
Between the construction of the many bunkers, a
single structure for civilian use was erected: anautobahn bridge consisting of precast elem ents andspanning a distance of 42 m across the river K lodzka
Nysa. The bridge was built in 1940-41 east of
Breslau (present day W roclaw in Poland) and is still
in an excellent state o f p reserv ation (1 998 ).A fter the war, Freyssinet referred to the two
G erm an bridges as « as se z mal» , alth ou gh at least on e
of them was directly designed by him and the other
on e com plies w ith h is co ncept fo r the first brid ge. T heway he dissociated himself from these objects isperhaps understandable, though, seen in the context
o f th e tim es.
A s described earlier, Karl Mautner had fled to
London in the summ er of 1939 with the results of theG erm an and French tríals in his luggage. In contrast
to the reception given to prestressed concrete inG ermany, it was the subject of an open debate at the
Society of British Civil Engineers in England. As
early as 28 May 1940, a trial girder was tested tofailure. Parallel to this, in 1940-41, what was thelargest bomb depot in the world at that time was
constructed in an underground quarry, using some3,000 prestressed concrete girders with a span of
Sm .
In England, as in Germany, Freyssinet' s 1929patent was used solely with straight prestressing
wires directly bonded to the concrete. Only in trial
forms of construction were precast segments
as sem bled w ith c urv ed p ost-te nsio ne d te nd on s.This segmental form of construction -based on
Freyssinet' s ideas- w as first used in 1944 in a bridge
in Djedelda near Tunis. The 7S-m etre-Iong bridgeacross th e M ed jerd a W adi h as a SO -m etre cen tral span
and was built w ith 3-metre precast segments byC am peno n B ern ard w ith ou t the direct co llab oratio n
of Freyssinet. It w as constructed because the A lliedarmies urgently needed a reliable line of access toFerryville (now Menzel-Bourghiba), where thelargest dry dock in the regio n was situated. Theb ridg e still stan ds to day, b ut it has been stren gth ened
in th e m id dle bay w ith tw o au xiliary transv erse b eam ssu pp orted b y p iers.
In the public debates about prestressed concrete
construction held at the Society of British Civil
Engineers, P a u l A bele s, an em ig ra nt fram V ie nn a,
disagreed w ith F reyssinet and M autner, w ho insisted
that the concrete should be free of cracks. Abelesclaim ed that this w as not necessary and that a further
20 to 30 per cent saving in the quantity of steel couldbe made if cracks were tolerated in the concrete.According to the extensive investigations he had
carried out, there was no danger of corrosion with
cracks of lim ited w idth, he argued. Paul Abeles m ay
therefore be regarded as the inventor of theq ue stio na ble te ch niq ue o f p ar tia l p re str es sin g.
W ithout doubt, the man who had the greatest
comm erc ial su ccess w ith p re stressed co ncrete p rio r to
1945 was Ewald Hoyer, who developed a system forsm a]] prestressed and pre-tension ed beam s w ith v ery
th in h ard -d ra wn w ires w hich h e n am ed « pian o-strin g-
concrete». The beams could be cut to any lengthrequ ired , since th e w ires ex pand elastically at th e cut
and re-anchor themselves instead of losing theirtension. Th is p rincip Ie had already b een described in
a French su pplem en tary paten t for w hich Frey ssin ethad applied. Hoyer was nevertheless granted a
German patent as a result of speciaI wartime
legislation, and in Gennevilliers near Paris, hemanufactured incredible quantities of beams for
bunkers in the German Atlantic Wall. As many as1,500 people w orked in the G ennevi]]iers plant, and
the occupying powers forced Campenon Bernard toplace a num ber of its engineers at the disposal of this
works. The thought that Hoyer's German patent was
not legally valid in France was something no one
d ar ed to e xp re ss .After a trem endous boom in the post-w ar years, the
history of prestressed concrete -at least that with
embedded tendons- is now coming to an end. Paul
Abeles was, unfortunately, m istaken in thepronouncement he made in London in 1940.Prestressing steel does corrode through cracking of
the co ncrete and even w ithou t cracks.
The cJose econom ic cooperation betw een France
and Germany as one knows it today had its origins inth e years b etw een the tw o W orld W ars an d con tinu ed
-albeit in a different form- during the Germanoccup atio n of France. In the post-war years, this
cooperation led to the creation of the European Coal
and Steel Com munity (ECSC) and ultim ately, by way
of the EEC, to the present European U nion.
A s th is brief h istory of prestressed co ncrete show s,these developm ents w ere cJosely parallelled in theb uild in g sector, w here early international lin ks w ere
forged between France, Germany and the UK. One
sees, therefore, that some of the seeds of modernEuropean cooperation w ere sow n during the darkesty ears o f th e 20th century.
Perhaps one may end this story on a more
conciliatory note. The painter Em il N olde, w ho fell
out of favour w ith the N azis for his «degenerate art»,
w as ultim ately no lon ger ab le to p urchase p aint. Q uiteby chance, his friend M ax Lütze was responsible at
W ayss & Freytag for maintaining contacts with
F rey ssin et, an d o n th ose o ccasio ns w hen L ütze v isite d
Paris, he bro ught back paint for N olde. H is pain ting sbelong to the m ost beautiful things that ever carne of
pres tr es sed conc re te .[E ng lish v ersio n b y P eter G reen J
REFERENCE L lST :
Grote, Jupp; Marrey, Bernard. 2000. Freyssillet, La
Précolltraillte et l' EuropelDer Spallnbeton ulld
Europa/Prestressing and Europe, 1930-1945. Paris:É ditio ns d u L in teau . ISB N 2 -9 10 3 42 -1 3-1
This volurne also contains a full list of the relevant
l it er at ur e a nd co rn r nun ic at ion s.Harris, Sir Alan. 1997. Freyssinet: The genius of
prestressing. London: The Structural Engineer, Vol.
