GTSTRUDL User’s Group Annual Meeting - 2012
SEISMIC SCAFFOLD
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June 15, 2012
Parimal Gandhi, PE
Sr. Engineer
PURPOSE OF SEISMIC SCAFFOLD
To provide guidelines and installation requirements
for scaffolds built in safety related areas
with regard to both personnel safety and plant equipment
operability.
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AGENDA
1. SCAFFOLD IN NUCLEAR PLANT
2. SEISMIC SCAFFOLD
3. NRC INFORMATION NOTICE 2007-29
4. DESIGN & ANALYSIS OF SCAFFOLD
5. SEISMIC DESIGN REQUIREMENTS
6. GUIDELINES FOR SEISMIC SCAFFOLD
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SCAFFOLD IN NUCLEAR PLANT
Temporary tube and coupler scaffolds are often used at
nuclear plants for various maintenance activities.
Scaffolds are not safety related.
Scaffolds are designed for dead weight and live load.
Scaffolds are unanchored, i.e. free standing.
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SEISMIC SCAFFOLD
In case of a seismic event, free standing scaffolds could
slide, oscillate and tip over.
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SEISMIC SCAFFOLD
Seismic Restraint for Scaffold to Avoid Sliding
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NRC INFORMATION NOTOCE 2007-29
 To alert licensees about recent operating experience at
nuclear power facilities where temporary scaffolding
installed to support maintenance activity has affected the
operability of safety-related equipment.
 The NRC expects that recipients will review the
information for applicability to their facilities and
consider actions, as appropriate, to avoid similar
problems.
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DESIGN & ANALYSIS OF SCAFFOLD
Striking Distance for Unrestrained Scaffolding
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DESIGN & ANALYSIS OF SCAFFOLD
 The Fundamental Frequency of Scaffolding 3.5 Hz.
 Critical Damping of Scaffolding > 7%
Sliding Distance of Scaffolding for 23 sec of SSE
Oscillation of Scaffolding
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DESIGN & ANALYSIS OF SCAFFOLD
 Per ASCE 43-05 Newmark I Equation for sliding
displacement
Per ASCE 43-05 Newmark II Equation for sliding
displacement
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DESIGN & ANALYSIS OF SCAFFOLD
STRUDL MODEL FOR SLIDING
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DESIGN & ANALYSIS OF SCAFFOLD
The Base Isolation Element
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DESIGN & ANALYSIS OF SCAFFOLD
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DESIGN & ANALYSIS OF SCAFFOLD
For Bolted Steel Structure 7% Damping SSE Horizontal
Acceleration Response Spectra
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DESIGN & ANALYSIS OF SCAFFOLD
Based on scaffold loading requirements and
dimensions vertical posts, bearer, runners and braces
etc. are sized from Excel Modular Scaffold Technical
Manual EMSLC-TSM-1001.
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DESIGN & ANALYSIS OF SCAFFOLD
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DESIGN & ANALYSIS OF SCAFFOLD
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SEISMIC DESIGN REQUIREMENT
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SEISMIC DESIGN REQUIREMENT
Design Load = DW +LL + Seismic
Where
DW= Dead Weight of Scaffolding (Include Hand Rails)
LL = Live load 50 lbs/ ft2
SeismicY = SWEv (DWy +0.25 LLy),
SeismicX = SWEX (DWx +0.25 LLx)
SeismicZ = SWEZ (DWz +0.25 LLz)
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SEISMIC DESIGN REQUIREMENT
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SEISMIC DESIGN REQUIREMENT
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SEISMIC DESIGN REQUIREMENT
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GUIDELINES FOR SEISMIC SCAFFOLD
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GUIDELINES FOR SEISMIC SCAFFOLD
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GUIDELINES FOR SEISMIC SCAFFOLD
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Questions?
Thank you.
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