World Exposition in
The Yugoslav Pavilion
Sometime in autumn of 1956 I received a call from Mr. Vjenceslav
Richter, an architect in
During the first meeting I was shown their model of the pavilion that took me by surprise for sure. I had to ask who suggested me to work out the structural design for an extraordinary pavilion. They obviously have been asking around the more experienced colleagues but nobody wanted to risk his reputation or just to waste time for a not executable structure at first glance at least. Looking at the rather intriguing model I felt some weird desire to take this task although I envisaged instantly that the solution would ask for a non-classic static design procedure.
The model photos from the competition prospectus DIKSI 2 by Vjenceslav Richer and Pavel Weber for the Yugoslav Pavilion on Brussels World Fair 1958. Left the model total view and a closer corner view at right.
The proposed structure would have to consider rather complicated forms of deformation and deflection including considerable pre-stressing forces in four main cables. On a rectangular space truss hang the pavilion cubicle with floor dimensions 32m x 40m. The pavilion box like that should not represent any particular structural problem despite its unconventional form. The deformation of hanger rods should be kept as small as possible not to influence the box structure hanging on the space truss above. The real problem presented the fixation of the rectangular space truss at its four corners onto the four main cables. The deflection of these cables should have the most significant setback in the whole design. Apparently the four cables should have to be designed for a rather large strain – probably subjected to a pre-stressed force.
First task was to make reasonable and stiff enough structure for the
pavilion cubicle in considering a symmetrical position of hanger rods in two
concentric parallelograms. The position of rods dictated the form of space
parallelogram truss on that the pavilion box hangs. Thus one could calculate
the pavilion and space truss dead load leading to the most decisive point of
the overall design. I had consulted a few elder colleagues at the Faculty of
Civil Engineering in
The four main cables would be strained by the space truss at four points about half way of the cable’s total length of say 65m each. Part of the structure’s vertical deformation would depend upon the vertical loads dead and live ones. The live loads could be applied non-symmetrically to the structure’s two main axes of symmetry that resulted in considerable horizontal (lateral) movements. The wind load would add its part to the additional lateral movements thus increasing the overall instability of system attached to cables only. This was for me the first time that was confronted to the second level of elastic deformation in an elastic system. This kind of deformation is the result of position change of structure’s center of gravity bringing the system out of its stability under a particular load arrangement.
Photograph of model corner close up Photograph of model front elevation
Three staircases perpendicular to each other (3-point fixation) would prevent the pavilion to rotate around its vertical axis. The rotational stability was one of the crucial points to be considered in particular because of the 4-point fixation on cables holding on the central column. The live load of visitors moving indiscriminately on the pavilion two floors could result in certain vertical as well as horizontal displacements. I believed that the installation of adequate hydraulic absorbers at the bottom of each staircase could smooth out any of such displacements also those caused by a quick live load dislocation or some sudden one say in case of panic.
The central column was double conically pointed having a maximum
diameter of say 1m and a total height of some 85m. The 4 cables fixed to a ring
at 45m above the ground kept the central column firmly in its position. The
whole structure should be made of steel and manufactured in
By end of February 1957 I have completed the preliminary structural
design that included a rough calculation of quantities for the building
materials for the pavilion. My companions have agreed to a new arrangement of
the pavilion interior to comply with the redesigned structure compared to the
prized model. Soon the three of us were invited to visit the Commissariat in
Around a long table sat about a dozen persons and the session started
with Commissary’s introduction asking about progress of the pavilion design.
The architect Richter informed that we achieved an agreement about the pavilion
form and other arrangements of arts. He asked me to refer about the proposed
structural design as this is the main objective of this meeting. At first I
went on with my explanations quite well but when it came to the 4 cables the
unrest rose in the audience with some loud objections from a few elder persons.
One of them was the professor for steel structures design on the University in
By my estimate one needed a cable of say 90 - 100mm diameter probably
not available on the market. However similar sized cables had been rescued from
the cable bridge over
The new design request did not present any major problem for me as the
columns had to be placed more or less at the same position like the one of
original hanging rods. It was agreed to rearrange the décor panels to enable
hiding the vertical truss stiffener between two adjacent panels. These
stiffeners provided the horizontal stability to the pavilion when subjected to
horizontal loads. The engineers of the appointed steel construction company
from Slavonski Brod asked for a minimum height of 900mm for the main beams of
steel profiles that was more on economic than on safe side. The architect rejected
this request allowing max. 600mm that I had calculated as needed for a box type
cross sections. One of contractor’s engineers was my colleague who cleverly
understood that the pavilion’s design is not necessarily to be an economic one.
The EXPO was a rare occasion to show the engineers’ capability to follow
esthetic aspects where the costs did not matter. The contractor left
Richter almost fainted when he noticed the columns’ dimension made of steel profiles. They looked really massive and ugly as made of large “I” steel joists only. I intervened again and proposed a column’s cross section that would be looking much thinner in the open space. The column had to be made in a cross like form out of 4 angle 100mm steel angle profiles welded together corner to corner. The narrow front of some 22mm width would be painted bright off-white where as the inner angles’ areas would be painted with black color. From far one would get an impression that the pavilion stands on petite “needles” where as the wider frontages would merge into the surrounding darkness. Richter was very pleased with my understanding of the esthetics. The contractor had to “grind his teeth” again but was happy with more steel weight and works to be paid for that was not his matter at all.
A few months passed and I got an order for a travel to
The eastern part
copied out from the Expo Map is the Yugoslav pavilion (above the
in the FOREIGN SECTION with three gates. At right is “ATOMIUM” the landmark of EXPO 1958.
The next day I walked over the EXPO grounds where many pavilions were in
various stages of construction. I saw that the lowest sphere of the “Atomium”
is erected already and passed by the huge plot of the
On the next two Belgian engineers appeared introducing themselves as the quality inspectors on the EXPO. They expressed their concern regarding the quantity of cement used in the concrete for foundations that well bellow the permissible in Belgian standards. I tried to explain my reasons based upon strength test results. We agreed that contractor could pour the concrete to finish that foundation now. However I had to visit the Head office in town for further consultation before continuing the concrete work. The next day I went to the town and found the Bureau of Survey and Quality Control (BSQC) that turned out to be a private company. I met there several more elderly colleagues and after an amicable conversation my argumentation was accepted to be a right one. The qualities of supplied gravel and cement were excellent enabling a considerable cost saving that was essential considering that all works on EXPO are of temporary character only.
The established good contact with the BSQC would turn out as important
in about a year. For the rest of my stay I had an easy stand controlling the
concrete pouring and the completion of a dozen of foundations. On evenings I
took the tramway to
On one such occasion I visited the
Throughout the sojourn I had to economize with my daily traveling
allowance that was US$10 per day including the rail ticket to and for
After we parted from the pub I had badly needed a walk before going to
bed. I noticed Mrs. Rosenberg walking her dog at the far end of street and
walked over to join them. The next morning I could not remember what we were
talking about last night. Madame greeted me in as usual in French saying: “Last
night you spoke in French so well to me. In future you should not talk to me in
German anymore, mon chere ami!” I was so perplexed I continued on in French
instantly doing so all through my stay here. When I came to the site Mr.
Obradović who was the Contractor’s chief engineer informed us about the
good news for the May 1. The Yugoslav embassy has booked a bus for all workers
for a one day trip to the coast on that national holiday in
Contractor’s workers on a day trip to Knokke (at left) and during lunch break near Brugge right.
Embassy’s representative at centre (dark glasses) and Mr. Obradovic second at right in back row.
The day was perfect for a trip starting from
At left the Lion
monument on a hill near
I visited the town of
Several months passed and I did not hear from Richter anything not even to mention that I did not get a reimbursement for my contribution in his project. Suddenly early in January 1958 Richter called me to visit him most urgently. When I arrived to his office he produced a strange looking object or form waving it in front of my nose and said: “You will have to design this “object” to be the column in front of Yugoslav pavilion!” Further he said this form reminds him of Calder’s Movables and that it would be a sensation on the EXPO. At first moment I was flabbergasted seeing three umbrella’s spoke bent making a bow each strung and fixed on a tendon of thin wire. Each bow was positioned at an angle of 120 degrees to each other and the ends were fixed to the sinew at the third of its length. By Jove, it proved to be a stiff “structure” and a very elastic one to stand straight upright too.
I just could not believe that this “form” could
be constructed into a column like structure of 6 bows (one each for
With joined efforts we were able to compute the first three bows only. The deformability of this system asked for the accounting of elastic first and second displacements that had to be evaluated step by step. At those times we used slide rules and mechanical calculators – lucky if you had one driven by electricity. I called on Richter to inform him about rather disappointing outcome of our tryouts. It did not make him happy at all as the Committee’s request was too adamant that the pavilion must get a striking column to be seen from afar. Richter was much upset and forced me to find the solution to create that “column” at what ever price of. Then like a strike of lightning I got the idea – to tiny bars holding the sinew at fixation point to the inner two bow’s pipes. Later I added a turnbuckle to each enabling correction on the sinew’s alignment to a vertical. These bars should be painted black that would make them almost invisible once the “column” is erected in front of the pavilion.
Richter liked this idea and urged me to start
with the necessary computations and drafting of the working drawings. In the
meantime he found a steel workshop in
The bow and the sinew fixed to by two bars had to be subjected to two test load cases A & B
My mentors complimented my idea of the two bars fixing the sinew at each bow’s third point allowing keeping it straight. This solution made the statical calculation much simpler so it could be completed for all 6 bows within two weeks. The calculation resulted in a great reduction of steel profiles thus of the total weight and of the exposed surface to wind load too. The necessary sinew steel profile became small so we had to choose diameters of 20, 25 and 30mm of the solid steel rods. Later the sinew was to be painted in dark grey making its round profile hardly visible against the background. A colleague suggested help to produce the working drawings as he was working for the plant producing the seamless pipes in Sisak.
The following weeks were extremely hectic for me
and I spent most of the time at the steel manufacturing workshop. I had to
supervise the shaping and welding of the many various steel profiles to be
formed to a bow. The first made bow subjected to load tests at the Institute
for Testing of Materials and Structures of the Civil Engineering Faculty where
I was employed as assistant. I arranged to test the bow subjected to lateral
loads at the two significant planes. The test’s results were rather promising
and proved that the design was correct and safe for its use. We barely
succeeded with the trial assembling in
In meantime the shallow pool and a Y-shaped slender bridge over it were completed according my design. The column and the pear-shaped support stood on a tripod of 3m height and placed over the “Y” corner of bridge with the sinew exactly over it. The column consisted of 6 bows 7,5m that lowest of sinew was fixed through the top of a pear-shaped latticed support of 8,5m height. The later one stood on a tripod and was kept in position by 3 pairs of tendons of round steel rods of 22mm diameter. The tendon upper end was fitted to the connection to the lowest bow. The lower ends of tendons were fastened to 3 anchor blocks of that the foundations were hidden under the pool. The total height was 45,5m as measured from the bridge top up to the peak of column. The column itself stirred up quite a curiosity and some anxiety and the rather slender bridge too. The overall design was my great “secret” that I wanted to reveal to the Belgian supervisors only.
At left the lifting hook holds the temporary assembled column and a worker checks column’s bearing joint on the “pear” support being the lowest structure’s element
Despite my limited traveling allowance we
managed we take the trip together so my wife would attend the opening ceremony
with me. However we had left our daughter at Liljana’s family in
At left the column being assembled on floor its top bow is the nearest one and start up of lifting at right.
When the tripod was erected a mobile crane lifted up the “pear” support on top of it. With the three pairs of tendons that had double-screw connections at each of end one was able to fix the “pear” firmly in the vertical position. One achieved a not-rotating stable “pear” by staining the tendons double-screw connection to the anchor block. Everything was ready for the column to be put on its pear-like support. In the meantime one assembled the six bows on the ground by fixing the sinews with pairs of cross-bars that had a turnbuckle on each bar. Thus we achieved an almost straight sinew line in adjusting the turnbuckles prior the column to be lifted up.
Soon after lunch break another mobile crane with a long boom arrived to lift the assembled column onto the “pear” support. First the short cut lowest third of sinew rod Ř30mm was carefully put through the opening on “pear” top. The column lower bow end was turned so that it passed through the “window” that was an opening left in one of the “pear” latticed side. The crane slowly lowered the column until the bow end plate sat firmly on the “pear” internal tripod support. A short Ř30mm rod was pulled in through the hole on support and its top end fixed with a turnbuckle to the short cut sinew end. Then the short rod bottom end was strained firmly using a double-screw joint too.
These procedures were completed within say two
hours when I instructed the crane driver to release from the hook a lifting
snare that fell to the ground. For the first time a complete column stood there
swaying slightly. The trial erection in
At left lifting and placing of the “pear” element and at left two stages of column lifting and moving in.
There was a lot of admiration for the erection crew coming from all present in final stages of completing the Yugoslav pavilion. The prompt column assembling within a few days was for me the greatest achievement and something extraordinary in view of the short time we had on disposal. The two supervisors of BSQC arrived when the column was up already and were rather astonished its “crazy” form. Later next day I would get the invitation from their office to give a lecture about my design explaining the column structural complexity.
The next morning I had to explain some structural details to the security officer who was worried about the tiny rods (Ř22mm) holding the “pear” support and the column going up swinging erratically under the wind. I told the officer that according my calculation the column peak would move for about 1cm at a wind speed of 1km/hour. That would mean that at wind speed of 50km/hour the peak would move for say 50cm. Then we stood on the bridge and looked up to the column and I was so astonished about the peak movements in an elliptic form that made me almost queasy. The officer was astounded too and looking at the 3 pairs of tendons asked: “Comrade Engineer, what would happen if one of these tiny rods gets cut maliciously?” On my first impulse I suggested to replace it instantly. Then even more worried he asked about if both rods of one tendon pair get ruined by explosive. I answered straightforwardly: “Get far away from the column fast! It will collapse for sure!” He left me alone most worried and deeply concerned with the security measures. He left irritated thinking about how to organize the necessary controls instantly.
I passed around the buzzing pavilion with the interior decorators and artists looking after their pieces of arts being properly placed within the pavilion area. I wanted to make out the progress on the Yugoslav restaurant that construction started belatedly. Our idea was to invite Mrs. Rosenberg’s son Roger and his wife for a dinner on opening day tomorrow. Thus we wanted to thank our hostess for giving Liljana the accommodation without any additional charge to me. Unfortunately the restaurant was by far not ready so I decided see the Commissar who acted like director of the Pavilion. On my way I met one of the BSQC supervisors who was looking after me and happily handed me a letter of invitation from his office. By this invitation the Bureau kindly asked if I could held a lecture to the Belgium Engineering Society about “the column” now standing firmly in front of Yugoslav pavilion.
At left the view
upwards from “pear” hold by pairs of tendons up to column tip. The erection
and the author (left at centre) standing on the bridge below tripod on right picture.
I went straightforwardly to the Commissar to explain the invitation and how it would be a good opportunity to publicize this unique project. I asked him for a few days of allowance extension that was to be beyond fixed time of my stay on the EXPO. He was rather busy and nervous about the short time left for all works to be completed on time so he bluntly refused my request. He said nervously: “Look, I have so many of these artists who mingle around not being able to finish their job in time. All of them want more daily allowances and I cannot spend more than my allowed budget means.” I must have looked at him with some distrust and misapprehension so he continued in appeasing tune: “Look, comrade engineer, you accomplished your task well and on point in time. You deserve to go home in good content what you did for your country.” I thanked him with a rather dour smile and left the site not to return to it anymore.
The views of the Yugoslav pavilion after the opening – at left the south elevation and the entrance at right.
On my way to my quarter I had to pass the
Hungarian pavilion where I found out that their restaurant was open. On my
first thought I went in a found the maitre d’ and reserved a table for 4
persons for the next evening. On the EXPO opening day of April 17 there was a
free entrance after the opening ceremony would be over that would save me
expense for entrance tickets too. Liljana was somehow surprised about early
return but she accepted to accompany me to the city where I had to the Bureau
regarding their invitation. My wife did not like the
Northern access to the pavilion at left (Portuguese pavilion in background) and the column total view right
We did not attend the opening ceremony and spent
the day in sightseeing the city centre. That evening Roger Rosenberg and his
pretty young wife arrived and drove in their car to the main entrance from
where it was the shortest way to the Hungarian restaurant. Table was ready for
us and after an aperitif of peach brandy we ordered meals to be Hungarian
specialties. The dinner passed in perfect mood except for me counting the costs
so that the end sum would not get over budgeted amount I had with me. When the
waiter brought the dessert menu I told my wife in Croatian to choose the
cheapest cake on the menu. Out of blue sky the waiter said in Croatian: “Take
the Dobosh tart. It’s very good and I won’t charge more than you can pay!” This
was the surprise of the day! The waiter came from
The pavilions colored pictures show Yugoslav pavilion at left and Hungarian one at right
Roger suggested he would take to the city and show
us something brand new in
~ ~ ~ ~ ~
The architect Vjenceslav Richter honored my contribution
and work on the project of Yugoslav pavilion rather late in 1958 after all. The
amount he paid somehow meager and not adequate for the time I have spent on
this project. However it helped us to finance the move to our first own flat in
Several years later Richter published an article
about the Yugoslav pavilion on the EXPO 1958 in
Early in 1959 Roger Rosenberg sent us the birthday card informing that his wife gave birth to a boy. Their son is the “result” of the dinner in Hungarian restaurant in April 1958. What a pleasing result it was!
The Yugoslav pavilion at EXPO 1958 World Fair
was renowned for its futuristic design. Now it is the best conserved of most
EXPO buildings and is still in use as a classroom in Saint Paulus
Copyright © Zvonko
Springer, Anif (
Photographs and colored enclosures:
1. Monograph of Vjenceslav Richter, Editor Vera Horvat-Pintarić; Printed and
Copyright by GRAFIČKI ZAVOD HRVATSKE,
2. B&W photographs from Zvonko Springer records.
3. Colored inserts are from following URLs: