Approach: Fault tree analysis

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# Approach: Fault tree analysis - PowerPoint PPT Presentation

Approach: Fault tree analysis. E 0 – Top event: operational failure or life-safety failure (two trees). E 0. E i – Basic event: damage of individual equipment. E 23. “or” - gate. “and” - gate. E 1. E 2. E 3. (E 0 occurs) if and only if (E 1 occurs OR both E 2 and E 3 occur). E 0.

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### Approach: Fault tree analysis

E0 – Top event: operational failure or life-safety failure (two trees)

E0

Ei – Basic event: damage of individual equipment

E23

“or” - gate

“and” - gate

E1

E2

E3

(E0 occurs) if and only if (E1occurs OR both E2 and E3 occur)

E0

E23

E1

E2

E3

Fault tree analysis (continued)

Mathematical equivalent of gates (independent events):

O

I1

IN

O

IN

I1

For the example fault tree:

Decision variables and top-event definitions

Events of interest and proposed Decision Variables (DV):

• Life safety failure: DVLS=P(LSF | T), where LSF is
• Occurrence of a life-threatening event, T = planning period (alternatively: DVLS=P(LSF|IM))
• Operational Failure: DVO=P(OF | T) or P(OF | IM), where OF is
• Repair or replacement time of critical equipment exceeds some threshold value DT0.
• Research products lost and the time to repeat the study is greater than some threshold value RT0.

Required performance level is specified by DVLS, DVO, DT0, RT0

Fault tree illustration for an LSA laboratory

Operational Failure

To be refined upon consulting Comerio’s database, Comerio and LSA occupants

Subject Die

Critical Equipment Failure

Data Lost

Env. Failure

Trauma

Microscope

is broken

Data storage

device is broken

Temp. Changes

Containment Failure

Basic event

(Damage State)

Hazmat Release

Tube is broken

Expected Results
• Result of calculation of DV=P(E0 | IM) by applying theorem of total probability
• Result of calculation of DV=P(E0 | EDP)

1.0

1.0

DV

DV

0.0

0.0

x1

x2

x3

x1

x2

x3

IM

IM

Each point corresponds to a particular value of the vector of EDP at the given level of IM

Where N – is number of simulations at the level IM=xi, and the right part probabilities are all conditioned on IM= xi

What we would like from structure modeler (Mosalam)

GM ID

SIM #

EDP ID

EDP Value

Files in formats: CSV, MDB, XLS.

What we would like from fragility testers

Fragility Parameters

DS

Assembly ID

Assembly Name

EDP Type

P1 (e.g. )

P2 (e.g.  )

Files in formats: CSV, MDB, XLS.

Expected Results (Simulation Technique)
• Result of simulation of E0| EDP, using generated El events
• P(E0 | EDP), using generated El events

1.0

E0

DV

n1

n2

m3

n3

m2

m1

0.0

x1

x2

x3

x1

x2

x3

IM

IM

• Generate basic event Eiaccording to distribution P(El | EDP = Vk)
• Follow Boolean logic of the fault tree to know if E0has happened
• Repeat for all Vk , and get ni, mi for each level of excitation IM=xi

Where mi – is number of simulations when E0 has happened, and ni – is number of simulations when E0 has not happened