Constructing structural safety – Lessons from the Eindhoven Airport parking building collapse

Constructing structural safety – Lessons from the Eindhoven Airport parking building collapse


In recent years several accidents have occurred
in which buildings have partially collapsed. Four of these incidents have been
investigated by the Dutch Safety Board. The Board’s most recent investigation examined
the partial collapse of a multi-storey car park,… …located next to the Eindhoven Airport terminal. The building had a modern
design with open floor plans. It’s floors were kept light and slim
by using bubble deck slab floors. A bubble deck floor is constructed
from individual prefabricated slabs… …made of a concrete base, reinforcing steel,
lattice beams and plastic spheres. Concrete is then poured onto the floor slabs. The plastic spheres mean that less concrete
is required, reducing the total weight. In a conventional application
the Bubble deck floor slabs… …span the distance between the
columns in the longitudinal direction. Deflection of the slabs is the
largest in the middle of the floor. The reinforcement bars ensure
that the floor does not break. In the case of the Eindhoven car park the decision
was made to rotate the floor slabs 90 degrees. The floor supplier and the contractor considered
this solution the best to meet the design requirements… …for a thin floor with a long span
and gradient for rainwater drainage. Rotation of the floor slabs resulted
in a vulnerable floor design,… …as it placed seams at the locations where
the deflection of the floor is the largest. No additional measures were taken
to overcome this vulnerability. Owing to the coupling reinforcement
bars being too short,… …the floor was unable to
properly bear its own weight. The warm temperatures of 27 May brought
about an additional temperature stress,… …causing the floor to collapse. Despite deviating from the
usual construction method,… …no attention was given to the possible
consequences of this design choice. Signals were not met with a response. None of the parties saw any reason to
have reservations about structural safety,… …although this could and
should have been the case. A shared concern for safety is not
self-evident in the construction sector. The Board sees a sector characterised by a limited
ability to learn and a low degree of self-reflection. Previous incidents and investigations
have not resulted in improvements,… …while parties are all too
ready to blame someone else. Construction projects often
have a complex organisation,… …in which multiple parties are
involved at different times. As individual parties do not oversee the
bigger picture the chance of error increases. This fragmentation of the
construction process also leads… …to a lack of clarity regarding
the allocation of responsibilities. As a result, safety risks go unnoticed
and no control measures are being taken. The lack of one central party to monitor the overall
construction process and to keep other parties on their toes,… …is one of the most important explanations
for the inadequate monitoring of safety risks. This conclusion was previously
drawn by the Dutch Safety Board… …and it was indeed the
case in Eindhoven as well. In addition, the Board notes that the competition in the
building sector is above all based on price instead of quality. If clients were to take safety more seriously,
the level of safety would be increased considerably. As municipalities conduct less supervision, the final check
of building constructions is increasingly skipped… …in a sector that takes insufficient
responsibility for safety. The Board considers it high time that the
building sector takes up this responsibility… …and implements the necessary improvements. Improved risk management is
needed throughout the building sector. Both clients and contractors must
bear their share of this responsibility. To this end, the Board makes
recommendations in the following areas: Expand the existing Construction Safety
Governance Code and make it less voluntary. Ensure clarity in the division of
responsibilities and their coordination. Appoint a single party to take overall responsibility
for risk management throughout the construction process. Investigate how this can be made mandatory. The Board expects the construction sector
to apply the principles of mechanics… …and the associated diagrams thoroughly. Builders are expected to
adopt a professional attitude… …by addressing any doubts and
critically reflecting on their own actions.

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