A terrible tragedy occurs at night in Mallorca. A discotheque collapses, people die. Norbert Gebbeken, structural engineer and president of the Bavarian Chamber of Engineers-Construction, explains how such tragedies can occur.

The drama occurs on Thursday evening. The “Medusa Beach Club” on Playa de Palma on Mallorca collapses and buries numerous people under its rubble. At least four people die and many are seriously injured. There are also two Germans among the victims.

The terrible accident leaves many questions unanswered. FOCUS online spoke to structural engineer Prof. Norbert Gebbeken, President of the Bavarian Chamber of Civil Engineers, about possible causes of the collapse.

According to the expert, building collapses without external influences – such as earthquakes or storms – are actually unlikely.

“If a building has been structurally correctly calculated and the loads arising from use have been correctly assessed, it should normally not collapse.” Something extraordinary must have happened in the current accident in Mallorca.

According to Gebbeken, possible causes could be unannounced conversions or changes in use that were not taken into account in the original static calculation. “If, for example, apartments suddenly become a discotheque where people dance, the burden on the building is completely different.”

Of course, one can only speculate at the moment about the exact causes of the collapse. According to several residents, the club was renovated “a few years ago”. The collapsed part was used as a rest area.

The British “Daily Mail” also reports that the club only posted a picture on Instagram on Wednesday with the text “New roof terrace”.

It remains to be seen whether any defects have arisen during any renovations. “In Spain, as in Germany, changes to buildings must be reported to the responsible authorities,” explains Gebbeken.

“For every change, a new static calculation is necessary, everything has to be approved, fire protection has to come in and so on.” These requirements would ensure that the buildings remain stable, says the structural engineer. “If these rules are not followed, tragic accidents such as the collapse in Mallorca can occur.”

For the expert, this means: “Something must have definitely gone wrong.” Whether unannounced renovations were carried out or whether the building was used for purposes other than those originally intended cannot be said without a more detailed investigation. “But something must have affected the statics of the building, otherwise it would not have simply collapsed.”

The expert believes it is unlikely that this could be due to the possibly old age of the building – nothing is known about this yet. “Even if the buildings are old, we observe that the basic structure of older buildings in particular is often very robust.” Gebbeken cites medieval buildings as an example.

Dynamic loads, such as those caused by the operation of a discotheque, are more likely to be the cause of the collapse. “These must be taken into account separately in the statics. Such dynamic loads can increase the originally assumed static loads by up to double.” If this is not taken into account during use, it can lead to the safety values ​​being exceeded.

An example: If you hop regularly in a certain rhythm, resonance vibrations can occur. “That always has to be ruled out,” says Gebbeken.

Because: “Resonance vibrations can cause any structure to collapse, as we know from bridges that are stimulated to galloping vibrations by the wind.” If such use is not statically accompanied, it would be grossly negligent.

Such tragic errors can be avoided through calculations by structural engineers or tests, explains the expert. “You can carry out load and vibration tests on existing structures, especially if you are planning to convert them. These then provide information about what needs to be done.”

In Germany, building collapses like those in Mallorca are almost impossible. “In Germany we have practically no building collapses under normal load conditions. Even if you include the case of Bad Reichenhall with 15 deaths, we have the safest building infrastructure in the world next to Switzerland and Singapore,” says Gebbeken.

If something happens, it will be during the construction phase or due to gas explosions. But these are not normal stresses, but catastrophic events.

Gebbeken emphasizes: “The monitoring system for buildings and the approval procedures are particularly thorough in Germany.” The so-called four-eye principle applies here. This means that for certain building classes such as restaurants or nightclubs, an independent test engineer must check the plans in addition to the structural engineer.

“This principle helps ensure that we in Germany have the safest infrastructure in the world, both in the event of earthquakes and in buildings in general.”

The actual reasons for the tragic collapse on Mallorca must now be clarified by experts who will examine the damage and the statics and check whether the building was converted.

“Unfortunately, it often happens that buildings are converted without this being properly documented or monitored by a structural engineer,” says the expert. This is particularly dangerous because, in the worst case, people die.