Metrodome Roof Collapse MSFC Presentation
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Transcript of Metrodome Roof Collapse MSFC Presentation
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Metrodome Roof CollapseDecember 12, 2010
Steven C. Maki, PE
Director of Facilities & Engineering
MSFC
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Metrodome Roof Operation & Care
Monitoring 24/7 basis
Experienced staff
Annual inspection and repair
Periodic roof surveys as recommended by Birdair
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Birdair Roof Surveys
Conducted in 2003, 2007, & 2010
2010 survey indicated fabric in good condition
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Metrodome Snow/Wind Incidences
3 snow collapses early 1980s with one panel replacement
1 wind incident 1986
No collapse or panel replacement in 27 years
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Snow Procedures
Preheat interior to 80-85 deg F air temperature
Hot air (150F) is directed between outer and inner to melt snow
Internal pressure increased by 50%
Manual snow removal if necessary
This procedure worked for 27 years
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December 10, 2010
Winter storm warning with projected heavy snow
Typical snow procedure is begun
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December 11, 2010
Overnight heavy snow/strong winds
Leo Pidde calls for manual snow removal 10:15am
Steve Maki on roof at 11am
Pressure is raised higher late morning
7 personnel on roof by 1pm
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December 11, 2010continued
Significant snow accumulations on roof/strong winds
Inverted triangular panels (tips) North/West sides
Decreasing temperatures
Conditions deteriorate; manual snow removal not effective
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December 11, 2010continued
Snow removal crew down at 5:30 pm unsafe conditions
Steve Maki/Leo Pidde pull drain plugs
All personnel off roof 6pm with plans to return next day 8am
Conference call made to postpone game
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December 12, 2010
Roof collapse at 5:03am
(play video) This is precursor to FOX video
Staff arrives to begin mitigation
Conference call with MN Vikings/NFL to cancel game.
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Initial Damage from Collapse
Panel 104 (triangle) ruptures from snow slide
Panels 43 & 44 (diamonds) rupture sequentially from snow loads as tons of snow and ice funnel to roof center
Panel 15 ruptures spontaneously about 5:30 pm on 12/15
Panel 35 ruptures after attempting to induce drainage 12/20
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Other Collateral Damage
Frozen pipes and broken seats
Minor structural damage to wind girt system
Damaged roof vents, lightning rods, inner liner
Other misc damage
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12/12/2010 HHH Metrodome
View towards panel 76
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12/12/2010 Internal View of Ruptured Diamonds
Approx. 9am view from Section 136 area
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12/12/2010 Panel No. 104
View from interior
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12/12/2010 View of Roof from Panel No. 104
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Roof Stabilization EffortsDecember 12-26, 2010
Significant snow loads/stresses on roof
Safety is no. 1 priority
Low outside temperatures hamper progress
Birdair, Geiger, WPM contacted and to site
Arrangements made with local firms to assist
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Roof Stabilization Effortscontinued
Initial focus is on repair
Birdair determines panel 104 is severely damaged and can not be temporarily repaired 12/14
MN Vikings game on 12/20 is switched to U of MN TCF Bank Stadium
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Roof Stabilization Effortscontinued
Ruptured panels are curtained or temporarily covered
Panel 15 ruptures suddenly 12/15
Work is stopped, work plan is reviewed for safety
Geiger designs roof restraint system using jersey barriers Birdair/Sowles installs system to ballast for wind loads
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Roof Stabilization Effortscontinued
Inner temperatures rise after curtain/covering
Panel drain plugs are pulled
Laser survey is used by WPM to acertain loading/damage
Roof structure is stabilized by Christmas
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Roof AssessmentDec. 26, 2010-Jan. 14,2011
Warm weather with rain
Photo survey of roof inner liner conducted; diamond panel liner removed (Geiger recommendation)
WPM recommends fabric samples to be tested
Strong winds New Years Eve tears panel 104 curtain
Sampling starts; cold/snow/winds slow efforts
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Roof AssessmentDec. 26, 2010-Jan. 14,2011
Seating reduction curtain removed (Geiger recommendation)
Birdair notes panel no. 100 in bad condition
MSFC requests Birdair perform roof survey
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Roof AssessmentJan. 15, 2011 +
Birdair roof inspectors arrive on site Jan. 18
Weather conditions hamper survey
Test results both bad and good
TT requests certain samples
Birdair reports roof panels in poor shape, tears/holes in triangles; survey completed 2/3
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Summary of Results to Date
5 panels ruptured with significant damage to remaining roof and liner
Testing results are good and bad
Birdair survey indicates roof in poor condition
Sliding snow/ice have degraded fabric; wind/wicking are negative effects
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Public Safety Concerns
No support for partial restoration of the roof
Significant concern if partial restoration, weakened fabric could fail during event causing panic
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Conclusions/Recommendations
Replace external roof fabric (cables are ok)
Replace inner liner above seating area (triangles/rectangles)
Save liner cost on diamonds by replacing with acoustical batt + increase heat transfer for snow melting
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Conclusions/Recommendationscontinued
New roof clamping required; remainder of roof system is good
Minor collateral damage cost wise
Remove seating reduction curtain
Syracuse experience provides positive results