Katowice,+Poland+-+Trade+Hall+Roof+Collapse

Trade Hall Roof Collapse //Animesh Aggarwal, Masters - Structures (Civil), 2013 // toc = =
 * Katowice, Poland - January 28th, 2006 **

=Introduction=

The roof of one of the buildings at Katowice International Fair collapsed in Katowice, Poland on 28 January 2006 at 17:15 (local time). At the time of the incident, an international exhibition of pigeons was on display in the building. The possible reason of the collapse was found out to be the weight of snow on the building. On the day of the catastrophe, the snow and ice loads on the roof were twice as high as that was recommended in the design standard. This collapse left 65 people dead and more than 170 were injured. The roof of the building had shown signs of inability to withstand the weight of snow before the event but due to improper management the organizers went ahead with the event which led to this disaster. Overview of the collapse is shown in figure 1.



=Keywords=

Katowice, pigeon exhibition, 28 January 2006, snow load, roof collapse.

=Background Information=

Dimensions of the KFB (Katowice Fair Building) general plan were 96.360 x 102.875 m. The roof of Katowice fair building consisted of a central lantern 47.00 x 52.75 m with a height of 3m as can be seen in figure 2. There were 8 other lanterns with the sizes 6 x 6 m and height of 2 m which were also placed on the roof. From the scheme of the steel structure it was observed that there were six main columns which were situated on the higher building’s contour and 66 columns spaced 6 m along the exterior walls. The external columns were hinged at both ends (to the foundation and to the roof structure). At the top of the columns, three main roof girders were supported on one of the axes. These girders were constructed from two coupled trusses and doubled trusses to create a quasi-box section which is sensitive to warping. Those trusses and purlins that belonged to the higher part of the building were supported by the upped nodes of the truss chords, whereas the lower ones were supported on the bottom nodes of the truss chord.

A similar construction was employed for secondary girders, for which a box cross section was made from 2 hot rolled channels constituting the upper and bottom chords. The triangular frames were attached from the upper side to the purlin, and were extra stiffened by 2 askew bars connecting bottom nodes of frames with the nearest support of the purlin. The rod bracings were not present at the roof plane, instead it was covered by corrugated sheets of polystyrene and heat-weldable roofing paper.



=Description of Collapse=

The roof collapsed on two adjacent axes, which led to the slide down of the structure and only the main girder on two of the axes remained on a single column. There was also damage to the top parts of main columns as they were not connected to framing elements properly. The external walls were bent towards the inside of the building as the middle of the building collapsed. The main girder had fallen down with a collapse of the lower part, which led to a fall down of the main girder as can be seen in figure 3. The system was unstable with the main girder being distorted but staying on the bearings. It crashed on 9th January 2006 with the central part reaching the floor. With the battens fracture, the columns were deflected and deformed.



=Causes of Failure=

The Katowice Fair Building was designed with a number of constructional and strength errors leading to its failure. The elements of the structure were created in a series system which is evident from figure 4, which collapses when only one of the elements reaches load bearing capacity, i.e. minimum critical set of ultimate elements = 1. In the series system, the most stressed element in the system decides the global safety. In this case, as the number of elements increase, the probability of a weaker element increases, which further reduces the safety of the structure. In this structure, the bracing were as important as the main structural elements. In this building, the main truss should have been braced in at least two planes, and vertical roof bracing should have been used for lower and upper roof parts.

Snow drift was present on the lower roof part which made the vertical load on the main girders asymmetrical. This snow drift was caused by the central lantern and the smaller ones. The maximum stress was along the main girder. Main girder’s chords faced permanent torsional displacements due to high value of torsional moments. There should have been a movable pin bearing on one of the sides of the girder as it was longer than 30 m and absence of mobility of the ends makes the girder unfavorable. The top of the columns collapsed as they were not connected to the framing elements properly and were not adequately finished. The bending of the leg was caused by the horizontal reactions, which was a result of arrested translations of bearings and torque movements. The field connections were incorrect as they were designed due to extreme internal forces, which meant that any random increase in the load would focus the safety on these connections. The increase in load in this case happened due to snow.

As the collapse was caused by the accumulation of heavy snow and ice on the roof, an investigation was done to know whether this was due to instability in the construction site as well. Katowice was affected by underground coal mining that made the area unstable and probably not fit for construction. It lies in the heart of Poland’s coal mining region where the ground below is strewn with derelict mine construction like tunnels, which lead to subsidence and sinkholes. A PS-INSAR analysis was done to find whether construction site defects were a cause of the failure. The results indicated that the deformation in the subsoil in that area was not significant enough as compared to the surrounding areas, whereby it can be concluded that the cause of the collapse was not mining related.



=Failure Prevention=

Strength of the structure was insufficient, battens were not strong enough and the framing elements were not properly connected to the columns to distribute the load. Above all, if there would have been a freedom of translation in the bearings of the main girders then it would have reduced the amount of horizontal reaction produced in the column and the collapse could have been avoided. = = =Conclusion=

The basic problem was the insufficient strength capacity of the structure, which was unable to carry the basic loads of the snow on the roof. In most of the trusses, the design strength limit was exceeded by 26.8-113.5%. On the day of the catastrophe, the snow and ice loads on the roof were twice as high as what was recommended in the design standard. There were very large horizontal forces on the main columns due to the faulty construction, especially without lacing. The battens were not strong enough to support this horizontal force. The top of the columns were unfinished so they were not connected to other elements as one head unit. The scale of the destruction could have been largely controlled by using bar bracing on the roof structure, by providing a freedom of translation of the main girder’s bearings, by avoiding the unequal loads which caused high torque moments in main girders and lastly, by the adequate construction of the main columns to take the load.

=Lessons Learned=

Although the excessive snow loads which were not expected, triggered the collapse but the main reason behind the collapse was the faulty design and construction. The main lesson learnt from this collapse is about the improper management and planning by the organizers, who went ahead with the event knowing that the building had previously shown signs of inability to withstand the snow load resulting in the loss of life of 65 people.

=Bibliography= This article discusses about the characteristics of the Katowice Fair Building. It describes how the building collapsed and provides a few structural solutions for the building. This study examines the snow induced building failure incidents in the United States between 1989 and 2009, their causes and failure modes. This paper presents an overview of the errors in design, execution and insufficient code provisions which could have been the reason behind the failure. This webpage provides a detailed history of the collapse describing the reasons behind it, rescue operations carried out and aftermaths of the incident. This paper investigates the types of construction errors in the steel roofs and determining there impact on the structures overall serviceability failure. This study analyses the structure to determine the level of deformation that had happened before the tragedy occurred This article is a news update on the incident the following day also mentioning the situation at the Katowice International Fair This article provides and overview of the Katowice International Fair and the questions that were raised after the collapse This article information on what preventive measures should be taken to avoid such failures in future This news article gives more details on the incident .
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