design of collapse-resistant structures
TRANSCRIPT
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8/12/2019 Design of Collapse-resistant Structures
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Uwe Starossek, Maren Wolff:Design of collapse-resistant structures
Hamburg University of Technology
Design of
Collapse-Resistant
Structures
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Uwe Starossek, Maren Wolff:Design of collapse-resistant structures 2/19
Hamburg University of Technology
robustness
progressive collapse
structural integrity
alternate load paths
continuity
redundancy
Keywords
isolation
compartmentalization
specific local resistance
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Uwe Starossek, Maren Wolff:Design of collapse-resistant structures 3/19
Hamburg University of Technology
progressive collapse
disproportion between local failure and resulting collapse
Some definitions
robustnessinsensitivity to local failure
collapse resistance
insensitivity to accidental circumstances
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Hamburg University of Technology
measurements and observations
admissible probability of failure
probability density functions(actions, resistances)
reliability theory
societal consensus
design values(actions, resistances)
Inadequacy of current design methods
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Uwe Starossek, Maren Wolff:Design of collapse-resistant structures 5/19
Hamburg University of Technology
Inadequacy of current design methods
structural resistance considered on local level only
(and not on system level)
accidental circumstances are neglected
(low probability events and unforeseeable incidents)
admissible failure probability cannot be specified
(risk of the type low probability / high consequence)
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Hamburg University of Technology
Inadequacy of current design methods
dont rely on reliability theory
use deterministic methods for design purposes
Conclusion
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Hamburg University of Technology
Design criteria
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Hamburg University of Technology
depend on significance as to consequences of collapse
(immediate losses, impairment of infrastructure, civil defense, national defense)
depend on exposure to accidental circumstances
(hazards of war, malicious action, natural disasters)
high for public buildings, major bridges, lifeline structures
Requirements (necessity of collapse resistance)
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Hamburg University of Technology
assumable extent of accidental circumstances
assumable extent of initial local failure
acceptable extent of collapse progression
acceptable extent of damage to remaining structure
applicable load combinations and safety factors
Design objectives
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Hamburg University of Technology
prevent local failure (high safety against local failure)
specific local resistance of key elements
non-structural protective measures
presume local failure (design for load case local failure) alternate load paths
isolation by compartmentalization
prescriptive design rules
Design strategies
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Uwe Starossek, Maren Wolff:Design of collapse-resistant structures 11/19
Hamburg University of Technology
isolation by compartmentalization
Design strategies Examples
key element
modification of structural system strengthening of transfer girder
design for load case local failure
provide alternate load paths (= redundancy)
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Hamburg University of Technology
Confederation Bridge, Canada
alternate load paths cannot be provided
isolation by compartmentalization
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Hamburg University of Technology
43421
Confederation Bridge, Canada
insertion
of hinges
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Hamburg University of Technology
Confederation Bridge, Canada
insertion of
hinges
compartment borders must be able to sustain either largeforces or large displacements
reduction of continuity can lead to increase of robustness
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Hamburg University of Technology
More examples
isolation by compartmentalization
Pentagon Building Paris Airport Terminal
weak strong weak weak
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Hamburg University of Technology
Murrah Federal Building Structural system
More examples
isolation by compartmentalization
collapse stopped at rebar discontinuityin transfer girder
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Hamburg University of Technology
A comparison
either less continuity or
more strength
more continuity,
more strength
properties of design
measures
large initial failuressmall initial failurespreferable for
noyessensitive toinitial failure size
at discrete locationsdistributed
over system
location of design
measures
alternate load paths compartmentalization
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Uwe Starossek, Maren Wolff:Design of collapse-resistant structures 18/19
Hamburg University of Technology
collapse-resistant design should be based on
deterministic methods
specific local resistance, alternate load paths, and isola-
tion by compartmentalization are all viable design options
continuity redundancy robustness collapse resistance
Some conclusions
a complete set of corresponding design criteria should
be developed and implemented in the codes
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Hamburg University of Technology
Thank you!