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The Last Look at Pécs: a Farewell to Magasház
Renowned as the tallest tower block in Hungary during the seventies and later as the tallest uninhabited building in Central Europe, Magasház (tall building) has been an emblematic building in Pécs. After several problems and changes of ownership, its demolition started during the spring of 2016.
Photo: József Orbán
At the time of our interview it had only ten stories (now just 3 stories - editor) out of the former twenty-five. József Orbán, professor emeritus of the Faculty of Engineering and Information Technology of the UP, who has paid particular attention to the story of Magasház for decades, talked about some of the technological issues regarding the tower.
Photo: Szabolcs Csortos, UnivPécs
Why is the high-rise building in Pécs so special?
The economic situation was relatively good at the beginning of the seventies in Hungary, so there was a competition among the cities to build the tallest block of flats in the country. Gyöngyös entered this contest with its 18-20-storey building and Budapest also had a candidate for the title. Because of this competition and rivalry Pécs began to construct a high-rise building in 1974 to create the tallest residential tower block in Hungary. Furthermore, it had to be earthquake-resistant. In 1963 there was a magnitude 6.1 earthquake in Skopje (part of Yugoslavia at that time), so the high-rise building of Pécs had to be a safe place. The reasons, however, were unreal: the first one was about politics, while the second one was based on a remote misfortune. Professor Zezelj, director of the Institute for Testing Materials of NR Serbia invented a special technology in 1957. This system was based on the prestressed connection of the structural elements, which applied flexible steel cables instead of rigid parts. This is the so-called IMS building technology, which makes it possible to build tall and earthquake-resistant blocks. I must add another human factor: Yugoslavia was a Western country during the seventies. Implementing this new technology required lots of travelling and offered the chance to spending money on rum punches, waterproof raincoats and jeans. During the construction of the high-rise building in Pécs this IMS technology was used to create the 82 meters high tower block on which had 250 flats on 18 000 m2 . By the way, 130 houses were also built using the IMS Technology in Hungary during that period.
Is Magasház the manifestation of the seventies?
In the seventies there was no reason to put a lot of effort into renovating old buildings. According to the socialist point of view the future meant tower blocks and ready-made reinforced concrete buildings. I myself had studied this in Moscow, we worked by this, this was our life. This aspect was shared by everyone: people were glad to move into new ready-made flats and leave the narrow, one-storey apartments with no comfort. Of course residents later on faced several problems such as noise, small rooms and small bathrooms. But in the seventies every building had to be built from precast or reinforced concrete. There weren’t enough masons to build the walls of the block of flats and the precast concrete plant produces the ready-made elements fast.
Photo: Szabolcs Csortos, UnivPécs
What is IMS technology?
The main point of professor Zezelj's patent was the application of steel cables in the post-tensioning process instead of affixing, welding, screwing or supporting with stanchions. Pillars and slabs are linked and work together via frictional forces derived from the bidirectional stretching of the steel cables stitched across the pillars. The gap between the pillars and the slabs has to be filled before stitching and stretching the steel wires. The filling material is a fast setting mortar which was the so-called PU paste in case of the Magasház in Pécs.
How did the problems with Magasház begin?
As far as I know, at first the inhabitants of the upper floors complained about water. The builders of Magasház knew that the wires were the key issue. Therefore they unfolded the nodes of pillars and slabs to check the corrosion of tensioned wires. Marks of corrosion had been found in 1983, but the examiners attached no significance to this neither did they advertise their findings. By the time of the next check in 1989 all the wires had become rusted, and there were even broken ones. The wires, which held the building together, were not solid any longer. All the wires were inside the structure of the slabs, that's why the wires could not be treated against corrosion. The vice-director of engineering of the property management company of Pécs, after several sleepless nights I bet, realized that he could not hold the responsibility for the condition of this building because of its state really became too dangerous. The building had to be evacuated to protect the inhabitants.
Photo: Szabolcs Csortos, UnivPécs
How long have you been paying attention to this story?
There was a course at the Institute of Geodesy and Soil Science about the corrosion of the Magasház of Pécs at Pollack (the former name of the faculty – the ed.) in 1989. The colleagues of the institute were great authority of this scientific field at that time. My field is material science, so I decided to attend this course. I have to admit, the topic was so special, that I hardly understood the jargon. I felt ashamed of myself, so I decided to make inquiries to comprehend the problems of Magasház in Pécs. I involved myself in this case for almost 2 years, and I published a study of 17 pages in the journal called Pécsi Műszaki Szemle in 1992. Later on I wrote in several journals specialized on corrosion.
What were the main problems according to you?
I could list several sources of error, each of them contributed to the destiny of the building.
One of the many is that the holes, in which the wires were set, were a little bit bigger than the wires themselves. This means that the holes were not big enough to be injected in but big enough to let air and water inside – and the steel wires could rust. There were installation gaps between the slabs and the pillars, and all these gaps had to be injected, too. The filling material was fast setting PU paste, but setting took 4-8 hours. Construction was going continuously, night and day, winter and summer. Workers wanted to save some time, so they added a binder for mortar called Kalcidur to advance the process. This binder contains calcium chloride and reinforced-concrete has two enemies: sulphates, that pulverize the cement, and chlorides that attack the steel. The question we have to ask: should we put mortar containing chloride into a gap where there are steel wires? According to the constructors the 25 millimetres of concrete should have been able to separate the wires from the chlorides efficiently. There are two problems with this argument: firstly, some of the steel wires contacted the PU-paste from the very first moment, so the concrete couldn't protect them. Secondly, chlorides went inside the concrete with a diffusion speed of 2-3 millimetres, and as soon as they reach the steel wire, poked holes into it. Just imagine the wires, which held the building together, getting rust holes! It's similar to cutting a canvas with a knife. In addition, the slabs got soaked during the construction, so the chlorides had been washed out from the PU paste. I must also add something else: it became clear during the demolition that the injections at some of the wire-gaps weren't perfectly compact.
Photo: Szabolcs Csortos, UnivPécs
But there was reinforcement in 2003...
The Magasház in Pécs is not an ordinary building, you can't just reinforce or underpin some of its elements, this building needed to be strengthened as a whole. When reinforcing it, the original structures ensuring its stability were completely ignored. To the pillars temporary structure were pressed, holes were drilled into them, through which new wires were led through. The wires were tensed with special tensioning tools became wedged. The joists were originally made of reinforced concrete ribbed slabs. During the reinforcement these ribs were drilled through, the new wires were coated with graphite grease and polyethylene was set into the holes and tensed in longitudinal and transverse directions. To reinforce the pillar-joist connection, further steel pins were built into the junctions. Since this solution involved a lot of additional steel, which the building wasn’t originally designed for, the pillars needed to be reinforced and supporting walls had to be built. This is how the bottom part of the originally specially slender building has become thick but stabile.
Magnificent plans could have been heard at the beginning of the century about how the Magasház should be renovated. Were these plans valid from the point of view technology and statics? Could the tower block have become residential again?
After the reinforcement this building could have been residential: statically it was absolutely stabile. It remained empty for financial reasons: all building service structures and electrical wires needed a change, the original elevators should have been replaced with more modern ones, and the Fire Department had objections, too. The ownership was a chaos: the building wasn't closed properly and nobody guarded it. All the windows and balconies were open, pigeons settled in, bird droppings covered the floors of the empty flats, the building soaked... It failed fast: it had become very shabby in a few years. The demolition was decided two years ago. And then, a 98 meters high tower crane arrived in March 2016, and the demolition began. The level of the demolition process is surrounded by guarding gates, which are lowered floor by floor.
The joint gaps of the front wall panels are explored with the demolition machines, the connecting and fixing steel elements are cut with a flame cutter, which unlocks the panels from the frame structure. A tower crane helps salvage the elements from the wall and bring them down to the ground. When unbuilding the joist elements, first the cable drains are crashed with the demolition machine, then the tension wires and cables are cut with a flame cutter. The next step is salvaging the elements with a tower crane and bringing them down from the building.
On the ground the elements are crushed into tiny little pieces by a biter (a kind of crocodile), and the recyclable steel wires are separated. The demolition has been made orderly and in a professional way, at a pace it was planned.
Why isn't there anybody who would take the responsibility? The loss of Magasház costs billions...
It was in the case of the Magasház when this technology was used in Hungary the first time. It was an experimental building. Errors could be expected in such a case therefore the architects could not have been made responsible. As far as I know, the Magasház has no full building permit. I think experimenting with such a high building was unfortunate.
To be honest, I really felt sorry for its demolition half a year ago, I would even voice objections. But today, as I have seen the corrosion damages and the construction problems revealed during the demolition process, I must admit that this building was in a far worse condition than we had thought. I was disappointed that the gaps of wires were not properly injected with concrete, but it's really reassuring that the stretching cables, which were used during the reinforcement, held the building together. If this high-rise building had been renovated after its reinforcement, it would have cost the same amount of money as its demolition, but then we could have a building of 250 flats.