Deteriorating support columns City of Bonn to shore up concrete pillars at the Stadthaus in October
Bonn · Steel sections are to be used to shore up 38 concrete pillars at Bonn's Stadthaus. These pillars are the most seriously impacted by erosion and the measure is considered a temporary solution for a maximum of five years. It is still unclear whether the entire building will be demolished.
About a year has passed since the city government made it publicly known that there was a massive structural problem under the Stadthaus (the building where people go for citizens’ services). Now it is preparing for temporary support measures for the dilapidated concrete columns on the parking decks. The work is scheduled to last until February; restrictions for motorists are to be expected.
The project involves 188 reinforced concrete pillars on both parking decks, which have been damaged by de-icing salts over the decades. According to the press office, there is no acute danger of collapse. But the 38 most severely eroded pillars must now be stabilized with steel profiles "to ensure the stability of the building," according to a memo for Thursday's city council meeting. An assessment, however, says all concrete pillars will have to be inspected annually thereafter and thoroughly refurbished starting in 2027 at the latest. By then, the council should have decided on the fate of the ailing municipal building as a whole: Either a general renovation or demolition and new construction - possibly on the site of the former state government building, the Landesbehördenhaus on the B9, which the city purchased from the state of North Rhine-Westphalia - are up for debate.
SGB has known about the problem for three years already
The Bonn Municipal Building Management (SGB) has been aware of the condition of the concrete columns on the parking decks since 2019. However, it was not until 2021 that Lutz Leide, then head of the SGB, informed the city leadership. Leide caused displeasure among Mayor Katja Dörner and the council coalition with his statement that extensive evacuation of the Stadthaus would probably be necessary for the provisional support measures - an assessment that was later refuted by an expert. In May 2022, Dörner parted company with Leide in return for a payment of around 400,000 euros.
The steel sections on the 38 concrete piers of parking decks 1 and 2, which are especially affected, will probably be installed starting in October. "At the moment, preparatory work is taking place on supply lines," explained Markus Schmitz from the press office. Motorists should be prepared for temporary closures of individual parking spaces, changes in traffic routing on the parking decks and heavy noise. Work will initially be carried out on P 1, and from November onwards on P 2.
Another feature requiring work in the Stadthaus: fire protection. A large part of the fire protection caps from the third basement floor to the second floor must be replaced, according to the city council document. "In order to examine possible compensatory measures, another fire protection expert has been commissioned," the administration wrote. After that, plans can be made for the next steps.
The city also wants to hire additional experts "in the near future" to examine whether the building complex from the 1970’s is worthy of preservation and can be renovated. The facade, shell, pollutant load and building technology are to be examined. "Insofar as structural engineering findings might speak against preserving the building, the reasons for this need (would need) to be spelled out," according to the submission. On the basis of the expert opinions, Mayor Dörner intends to present a draft resolution to the city council in the first quarter of 2023. (Orig. text: Andreas Baumann / Translation: ck)
