FC+Twente+-+De+Grolsch+Veste+-+Stadium+Roof+Collapse

FC Twente - De Grolsch Veste - Stadium Roof Collapse //Kyle MacDonald, The Pennsylvania State University 2016 // toc
 * Enschede, Netherlands - July 7, 2011 **

Introduction
Approximately noon (12:00 P.M.) on July 7, 2011, the stadium roof of the De Grolsch Veste in Enschede, Netherlands partially collapsed. The partial collapse occurred during construction of an extension to the stadium, causing 12 workers to fall from a height. In total, the incident resulted in two fatalities and nine injuries. After investigation, authorities have concluded that the partial collapse was due to a combination of technical and human factors concerning structural stability as well as construction management practice.

Opened in 1998, Stadium De Grolsch Veste, boasting an original capacity of over 13,000 seats, is home to the Dutch professional football club, FC Twente. Founded in 1965, FC Twente possesses a rich heritage of European football history. Due to the culture and history of the club, FC Twente exponentially gained supporters and sponsors throughout the years, prompting the assertion of a new plan to expand their stadium facility. In 2008, De Grolsch Veste underwent expansion, increasing the stadium's capacity to 24,000 seats. Due to the high demand for expansion, the stadium, and subsequent roof, extension was initiated, requiring construction of additional grandstand seating. Due to inadequate bracing and poor construction practice, the roof collapsed during construction, halting the anticipated expansion of Stadium De Grolsch Veste.

Events Leading Up to the Collapse
The football club, FC Twente, competes in the Eredivisie, the highest level of professional footbal in the Netherlands. Among the recent years, FC Twente has experienced great success within the domestic league and has added to its list of accomplishments as a club. In the 2000/20001 season, FC Twente finished mid-table within the Eredivisie but won the Dutch Cup, a domestic competition between all professional Dutch football teams (inclusive of each tier of professional football within the Netherlands). Futhermore, in the 2009/2010 season, FC Twente won the Eredivisie, becoming champions of the Netherlands for the first time in club history (Club History, 2010). Increased popularity and support were a direct outcome of the success and achievement of the club. The body of supporters grew exponentially during their history-making season. As the body of supporters and sponsors of FC Twente exponentially grew, the demand for a stadium able to accommodate a greater capacity of seating increased.



Collapse
Approximately noon (12:00 P.M.) on July 7, 2011, the stadium roof of the De Grolsch Veste in Enschede, Netherlands partially collapsed. The collapse of the roof structure, constructed in a U-shape configuration, occurred along the sideline (long-side) of the playing field. A total of six framed-truss bays partially collapsed, leaving remnants of the compromised structure strewn across the permanent grandstand seating of the stadium. The stadium extension and associated roof structure extension were in advanced stages of construction when the collapse occurred (Brady, 2012). The collapse was triggered by the removal of the last temporary structural stabilizing element (structural steel cable). The removal of this temporary stabilizing element subjected the incomplete structure to excessive loading conditions, causing the partial collapse of the roof structure of Stadium De Grolsch Veste. The collapse was deemed a structural failure attributed to a combination of both technical and human factors. Structural instability, ambiguous work responsibilities, and accelerated construction schedule were among some of the many factors that were investigated and determined to have shared cause of the partial collapse of the roof structure.



Investigation & Cause of Failure - Technical Factors
After the p artial collapse of the stadium roof at De Grolsch Veste, the Dutch Safety Board was contacted to investigate the cause of the failure and assess the damage inflicted upon the stadium at large. Many factors, both technical-based and human-based, were determined to contribute to the partial collapse of the roof structure. Among the varying factors that were determined to be a cause of the failure, three primary technical factors were concluded to be directly associated with the partial collapse: instability of the structure during construction, excessive loading conditions during construction, and secondary effects caused by dimensional deviations from the design of the structure during construction.

During the construction phasing of the project, temporary bracing, in the form of steel cables, were being used to provide stability to the roof structure. As the project progressed, the temporary stabilizing cables were removed, requiring the permanent bracing components of the structure to engage and support the loads and forces acting on the roof. Upon removing the final temporary stabilizing cable, the partial collapse o f the stadium roof was triggered. Upon investigation, it was determined that the temporary bracing was removed before adequate permanent bracing was erected. The absence of coupling pipes at the back ends of the roof beams as well as stabilizing connections in the roof structure contributed to the partial collapse of the roof structure.

Additionally, excessive and stressed loading conditions over the duration of construction contributed to the failure of the stadium roof structure. The incomplete roof was subjected to additional live load via a video wall, suspension bridge, and piles of roof sheeting material. In combination with the workers performing construction services on top of the incomplete roof, the excess loading distributed further stresses within the structure. Under the design conditions, the unaccounted load may have exceeded the capacity of the incomplete roof structure, triggering the failure of the under-capacity components of the structure.

Furthermore, certain dimensional deviations from the design of the structure during construction subjected the incomplete roof structure to additional loading. The dimensional deviations executed during construction of the structure caused a mismatch of the geometric harmony of the interrelated concrete and steel structures. Due to this mismatch, structural components were force-fitted into their proper configurations, deforming those building elements from their original form. The forced deformation of these structural components introduced additional stresses within the stadium roof, reducing the load-carrying capacity of the structure.

The sequential activation of each individual technical failure increasingly worsened the circumstantial conditions imposed on the partially constructed roof framing structure of Stadium De Grolsch Veste. The additional live load as well as additional stresses experienced by the partial structure created a condition of structural overload. Due to the excessive stresses and loading conditions already imposed on the partial structure, the removal of the temporary structural bracing element triggered the structural failure. Working in combination, the summation of all three conditions contributed to the structural overloading and structural instability scenario.

Ultimately, the combination of inadequate bracing and excessive loading conditions lead to the technical failure of the roof structure of Stadium De Grolsch Veste.

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media type="custom" key="28156585" media type="custom" key="28156575" **Note: The above images are embedded courtesy of Getty Images:** __Left Image:__ Figure 3: Connection Failure [IV-Images/Getty Images] | __Right Image:__ Figure 4: Instability Conditions [IV-Images/Getty Images]

Investigation & Cause of Failure - Human Factors
In addition to the technical causes of collapse, an array of human factors contributed to the collapse of the stadium roof structure of FC Twente's De Grolsch Veste. The investigation of the stadium roof failure concluded that the majority of the human-based factors contributing to the partial collapse concerned the matter of controversial construction management practice. Among these factors, three primary claims were asserted: sequential construction vs. simultaneous construction, ambiguous framework of construction, and lack of coordination and communication during construction.

FC Twente's desire to produce a "football-ready" stadium as soon as possible prompted the main contractor of the project to alter the construction schedule to attempt to fulfill the wishes of the client. Due to the time-related pressures associated with the project, the main contractor applied an altered principle of simultaneity to the construction phasing rather than executing the originally established sequential phasing of construction. Upon altering the phasing of construction, no assessment regarding the relationship between schedule change and worker safety was completed. Authorities concluded that the main contractor disregarded measures of safety when initiating the use of an incomplete structure.

Beyond the issue of construction phasing, the main contractor failed to outline an unambiguous framework of construction that would be used to execute the constructi on of the expansion of Stadium De Grolsch Veste. The responsibilities and duties associated with the construction processes of this building project were deemed to be obscure, both in the nature of assignment as well as performance. Construction responsibilities were not properly assigned, and construction duties were not properly performed. The framework of construction did not adequately outline the expectations of all parties involved in the construction process, causing confusion regarding scope of work and level of quality within the boundaries of the building project.

Due to the ambiguous framework of construction, the construction processes being executed throughout the project were not being coordinated properly, and the indivi dual trades involved in the scope of work did not have an appropriate system of communication and evaluation. As part of the contractual circumstance of this stadium expansion project, the main contractor and subcontractors working on the stadium roof structure had previously worked together on the construction on the original Stadium De Grolsch Veste; therefore, a high level of trust was mutually observed between these two parties. The high level of trust between the two parties resulted in a failure to monitor the performance of a number of responsibilities key to maintaining structural safety.

Ultimately, the combination of construction phasing alteration, ambiguous construction framework, and coordination and communication issues between parties involved in the project promoted a failure-prone atmosphere.

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**Note: The above images are embedded courtesy of Getty Images:** __Left Image:__ Figure 5: Resulting Work Injuries [IV-Images/Getty Images] | __Right Image:__ Figure 6: Emergency Response [IV-Images/Getty Images]

Prevention
Although a very serious and unfortunate incident, the structural failure of the roof at Stadium De Grolsch Veste could have been prevented. Statistically, the foundation of knowledge concerning the building engineering industry demonstrates that the majority of structural failures occur as a consequence of errors in planning, design, construction, and utilization (Ellingwood, 1987). Therefore, great care must be taken in each phase of the building project in order to ensure the integrity of all engineering and construction practice. Often, errors are caused by a departure from the accepted practice. By accepting the potential penalties associated with a delayed construction schedule by remaining true to the original construction work process, the mechanism of the structural failure could have been thwarted and the partial collapse of the stadium roof structure could have been prevented altogether. Once deviation from the original sequential framework of construction occurred, an error-prone construction atmosphere was generated and ultimately, conditions unrealistic to the scope of work were established. Ultimately, greater care in the coordination and communication of the original construction process, inclusive of essential construction tasks and checks, could have prevented the partial collapse of the roof at Stadium De Grolsch Veste.

Similar Cases
Paralleling the roof structure collapse of Stadium De Grolsch Veste, the B-Tower in Rotterdam, Netherlands experienced a similar collapse just a year prior (2010). Due to a combination of structural stability and construction practice issues, a 300 square-meter concrete floor experienced a structural failure during the construction of the B-Tower (Brady, 2012). After investigation, it was determined that the structure was put into use despite that fact that the structure lacked structural elements that were essential to stability. Three primary inadequacies, concerning construction management practice, were cited as the causes of the structural failure: lack of a joint approach to safety, inadequate coordination and checking, and a diffuse allocation of responsibilities. These same coordination and communication issues existed as the root causes of the roof structure collapse of Stadium De Grolsch Veste, demonstrating a lack of institutional memory within the building construction industry.

Conclusion
The partial collapse of the roof structure of Stadium De Grolsch Veste was a very serious and unfortunate incident that could have been prevented altogether. Ultimately, negligence of structural bracing elements, within the structural frame of the stadium roof, as a result of construction error triggered the collapse. Excessive loading conditions imposed on an incomplete structure was the mechanism by which the structural roof frame failed. Beyond investigation of the structural failure, the Dutch Saftey Board issued a conclusive document, asserting various recommendations to the multiple parties involved in the failure. The scope of the recommendations concerned general building construction practice, in the context of the shortcomings of the construction management techniques employed during the construction of Stadium De Grolsch Veste. Within this conclusive document, priority was given to the improvement of work safety in the building construction industry. Asserted requests, executed by the Dutch Safety Board, were as follows (Dutch Safety Board, 2012):

1) Realistically outline the conditions under which all parties can perform planned work 2) Ensure that safety measures be upheld and enforced during the construction process 3) Report on the weaknesses or shortcomings of the construction process and define contractor's responsibility in the context of the preservation of work safety 4) Create an action plan outlining the method by which explicit duties are assigned to the involved parties within the construction process 5) Make an effort to include parties non-inclusive of the trade association in this construction process improvement

Ultimately, responsibility for the structural failure and future construction practice and process was assumed. The collapse of the roof at Stadium De Grolsch Veste will serve as a reminder of the importance of proper construction practice and process within the building construction industry and strengthen the institutional memory of the industry.