New research has called into question the decsion to close Rio de Janeiro’s Joao Havelange stadium in March because of fears that the roof was unsafe.
Evidence from the UK building research body BRE has been used to question a report by German engineers, which said that the roof could collapse if wind speeds exceeded 18m/s.
The Rio de Janeiro stadium is due to be a key venue in the 2016 Olympic Games. It was closed in March after German consultant Schlaich Bergermann und Partner (SBP) issued the warning about wind loadings (NCE 11 April).
But now the Brazilian Association of Structural Engineering and Consulting (ABECE) has called for a review of the SBP report. It has citied a BRE study that questions the wind tunnel tests used to justify SBP recommendations.
The tests referred to by SBP were carried out in 2012 by German laboratory Wacker Ingenieure. However, Wacker came up with very different figures from the tests carried out in 2004 by Canadian firm Rowan Williams Davies & Irwin (RWDI) which dictated how the stadium was engineered.
An ABECE analysis of the tests said: “There are large differences in loading matrices recommended by both laboratories, in such a way that, in certain cases, Wacker shows, for the same situations, results of three times the [matrices] found in the RWDI test.”
ABECE called in the BRE to advise on the accuracyof the two sets of wind-tunnel results.
The unnamed author of the BRE report wrote: “In light of all of the issues discussed in this review, I believe the RWDI 2004 test results more than I believe the Wacker 2012 test results.
“…In consequence I am of the professional opinion that the RWDI wind tunnel test results should be used to determine the structural design of the [stadium] roof.”
The BRE findings have led ABECE to call for a reappraisal of SBP’s report.
“It is clear that these discrepancies led to divergent results between the unique structural design and the opinion of SBP,” said ABECE.
Gordon Masterton, chairman of the UK’s Standing Committee on Structural Safety, described the news as “surprising”. He said it would now be crucial to understand why the two results were so different.
“This could be due to different levels of sophistication in the physical modelling but could also be due to different means of converting the laboratory results to a full scale loading pattern,” said Masterton.
“Either way, it is important that the two approaches are understood, their differences can be explained and that a balanced view is taken on conversion of model results to the most likely representation of reality.”
The development is yet another twist in the ongoing saga that has heaped huge pressure on Rio Mayor Eduardo Paes, who last week promised to “punish” those responsible for any structural defects.
Speaking to Brazilian media Paes said: “I was not the mayor who built this stadium but I do not want to shy away from my responsibility now. Things were done at the last minute. We will establish who is responsible and the culprit will not go unpunished.”