B1/2001Y Ceiling of a market falling down in Jyväskylä on 26 April, 2001
On April 26, 2001 a hazardous situation arose in the Mäki-Matti city sector in Jyväskylä, Finland, when a part of the ceiling of a grocery store and some suspensions fixed therein collapsed soon after the closing hour of the store. When the first signs of the coming incident were detected, there were still one customer and some cashier personnel in the store premises. But when the actual collapsing took place there was only one guard within the premises, and luckily he managed to escape to the warehouse of the store. Among other items, all six fluorescent light lines collapsed, as well as some guide panels, spotlights, the guide and window-dressing framing above the cash registers, and ceiling boards made of mineral wool over an area of about 130m². Furthermore blow wool from on top of the wool boards penetrated into the grocery store premises.
The ceiling built in 1972 collapsed as a result of its overloading with different suspension mountings. Actually the ceiling featured a system invented and patented in the turn of the 60s and 70s; it consisted of 100mm thick 900x2000mm mineral wool boards. The wool boards were attached to each other by means of a building-mortar resembling binding agent and suspension mouldings made of steel. The suspension mouldings were hanging as supported by wires fixed in the bearing ceiling structures. In the suspension mouldings between the wool boards, suspension parts had been mounted carrying the six original fluorescent light lines of the grocery store. However in later phases the light lines had been further loaded by additional installations, e.g. guide panels, spotlights, refrigeration apparatus pipes and electric cables. The capacity of the suspension parts carried by the suspension mouldings had been exceeded by the additional load, and as a result the suspension parts had begun to break. As the load stressing a broken suspension part regularly moved over to stress the following suspension part, the breaking of the suspension parts took place as covering almost the entire store area. The broken and detached suspension parts pulled along the mineral wool boards in the ceiling over an area of about 130m².
In the planning, design and building of the ceiling in 1972 it seems that its service life was not intended to be as long as almost 30 years. Moreover any future needs of additional suspension mountings in the ceiling in the coming decades were hardly considered at the initial planning phase. The choice of this particular ceiling structure system was probably influenced by the fact that the grocery store building was first only granted a temporary building permit for five years. Consequently in the building project as a whole, it was the most economical and easily dismountable and transferable solutions that were adopted.
In order to avoid and prevent corresponding ceiling collapses, the Accident Investigation Board of Finland reiterates its recommendation B2/00Y/S3 included in the investigation report B 2/2000 Y on the collapsing of the ceiling of a supermarket at Pudasjärvi on December 27, 2000. The recommendation suggests that the maximum suspension loads be necessarily specified in the instructions for use and maintenance of the buildings or in a loading plate to be placed in the premises concerned. Furthermore the Accident Investigation Board recommends that the persons responsible for the upkeep and maintenance of shop and other buildings be fully aware of the loads actually stressing the ceilings and ensure their corresponding resistance.