Dutch-based Bam has revealed the results of investigations into the technical cause of the partial collapse of a car park in the Netherlands.
The P1 car park at Eindhoven Airport was under construction when it collapsed on May 27 this year.
Following the collapse there have been two investigations. The first by the Netherlands organisation for applied scientific research TNO, on behalf of Eindhoven Airport. Bam assigned engineering consultant Hageman to investigate the technical cause of the collapse. The conclusions from the investigations concur.
The car park used BubbleDeck floors, which are precast concrete floor slabs embedded with weight-saving plastic balls. After installation on site, a concrete topping was applied.
A statement from Bam said: “The investigations show that the shear strength of the interface between the precast concrete floor slabs was insufficient to convey the traction. As a result, the structural capacity of the floor was compromised. The high ambient temperature on the day of the collapse was a contributing circumstance to the defect manifesting itself.”
Bam also said structural engineers and building inspectors in general do not factor in enough the importance of shear strength for the adhesion of the floor.
It said: “The assumptions for the design and calculation of concrete structures are described in the construction standard NEN-EN 1992-1-1. In addition to the investigation it has been found that both structural engineers and building inspectors in the application of precast concrete floor slabs generally do not adequately recognise the importance of shear strength for the adhesion of the floor. An additional guidance of the NEN-EN 1992-1-1 would certainly promote the application of the standard.”
Bam Bouw en Techniek director Jaap Hazeleger said: “Fortunately an event like this is highly exceptional. We are very grateful that no personal accidents have occurred. With the investigation results in hand, we will engage in further talks with Eindhoven Airport to determine the most appropriate follow-up steps.”
Bam said it is sharing the results with the industry and now there will be discussion to determine the future of the building and who can be held responsible for the incident.
There were no injuries due to the incident.