Please read this before using presentation
• The Department of Mines and Petroleum (DMP) supports and
encourages reuse of its information (including data), and endorses use of
the Australian Governments Open Access and Licensing Framework
(AusGOAL)
• This material is licensed under Creative Commons Attribution 4.0 licence.
We request that you observe and retain any copyright or related notices
that may accompany this material as part of attribution. This is a
requirement of Creative Commons Licences.
• Please give attribution to Department of Mines and Petroleum, 2015.
• For resources, information or clarification, please contact:
RSDComms@dmp.wa.gov.au or visit
www.dmp.wa.gov.au/ResourcesSafety
www.dmp.wa.gov.au/ResourcesSafety
1
Structural integrity: The issues
www.dmp.wa.gov.au/ResourcesSafety
2
What are we going to cover?
• My experience
• What structural failures have happened recently?
• Historical and common knowledge – structural
hazard awareness
• Examples for discussion
• What is often missed and why?
www.dmp.wa.gov.au/ResourcesSafety
3
My experience
www.dmp.wa.gov.au/ResourcesSafety
4
Some structural failures on WA mine sites
• Acid leach tank – 2 million
litres
• Temperature > 95ºC
• SG > 1.4
• No fatalities
• Potential for
multiple fatalities
www.dmp.wa.gov.au/ResourcesSafety
5
More structural failures on
WA mine sites
•
•
•
•
•
•
Winder shaft and sheaves
Rock pass and bin
Jib crane (above right)
Take up plinth (left)
Radial stacker back stay
30t gross weight mixing tank
Possibly more but not reported due to no injury and not
deemed critical by the mine management
www.dmp.wa.gov.au/ResourcesSafety
6
Ask yourself
• What awareness do we
have of hazards?
• Is this from knowledge,
training and experience?
• Does it change with time?
• Do we learn from nearmiss or other events?
www.dmp.wa.gov.au/ResourcesSafety
7
Historical awareness
Importance of structural integrity
recognised for over 3,800 years!
King Hammurabi (1792 – 1750 BC)
Code – if a building collapse kills the
owner, the builder will be put to death.
Structural safety standards are
constantly evolving as failure events
result in loss of life ― standards are
updated to account for learnings from
failures
www.dmp.wa.gov.au/ResourcesSafety
8
Why is structural integrity important?
• Structural collapse can be sudden
• Structural collapse can results in multiple fatalities
• Degree or level of structural integrity and robustness
is not readily observable
– Load cases are not visible
– Loading is probabilistic
– Strength is calculated (can also be proof-tested but this
is uncommon due to each building being unique)
– Latent defects may exist
• Level of integrity and robustness is not immediately
apparent and may not be adequate
www.dmp.wa.gov.au/ResourcesSafety
9
Summary of awareness – human factors
With so many warnings and centuries of knowledge of
structural robustness requirements, why do structures
continue to fail?
• Misplaced optimism, even complacency
– “It won’t happen here or to me” (we tend to be optimists)
– “It hasn't happened that I can remember” (it’s always too strong)
• Competency
– Management not identifying risk
– Not utilising sufficiently competent persons in all phases of the
life cycle
So what does unacceptable look like ?
www.dmp.wa.gov.au/ResourcesSafety
10
What is wrong with this?
• How safe is this?
• Would you sit
under this
structure?
• This is on a site
that is well into its
asset repair
programme!
www.dmp.wa.gov.au/ResourcesSafety
11
Discussion
• Is a total catastrophic collapse required to prove that
a structure is in an unacceptable integrity state?
• Would you be happy with structural failures of:
– Aeroplanes, cars, trains?
– Your children's school hall?
– Your house?
• Aircraft are de-commissioned before catastrophic
collapse. Why are mining structures any different?
• Should this state of structure be tolerated?
• Why has it not collapsed yet?
• When will it collapse?
www.dmp.wa.gov.au/ResourcesSafety
12
Steel corrosion notes
• Corrosion is common in steelwork but can be
exacerbated by poor practice:
–
–
–
–
damage of corrosion protection system
inappropriate corrosion protection specification
lack of appropriate monitoring and maintenance
poor housekeeping (spillages not removed)
• Corrosion of high stress areas is commonly
overlooked by asset management teams when
assessors are not competent in design of structures;
for example
– high stress areas are not identified
– structural function (load transfer) is not understood
www.dmp.wa.gov.au/ResourcesSafety
13
What is wrong with this?
• Has this
failed?
• What
indicators do
you see?
• How easy is
this to repair?
www.dmp.wa.gov.au/ResourcesSafety
14
Discussion
•
•
•
•
Are bases important to steelwork – how?
How much strength does this base have?
What loading condition would result in total collapse?
How would repairs be undertaken?
www.dmp.wa.gov.au/ResourcesSafety
15
Concrete damage and degradation notes
• Loss of bond strength between reinforcing and
concrete – spalling
• Loss of concrete strength due to breakdown,
including alkaline aggregate reaction
• Total fracture due to:
– overload
– poor design and detailing
– impact damage
• Lack of loading combination considerations:
– thermal expansion and contraction (Pilbara 45ºC)
www.dmp.wa.gov.au/ResourcesSafety
16
What is wrong with this?
• How many
problems can
you find?
• What can be
done about
this?
• Refer to article
in Resources
Safety Matters
vol. 3 no.2
www.dmp.wa.gov.au/ResourcesSafety
17
Discussion
• More complex problems require intimate knowledge
of
– structural systems and construction techniques
– secondary effects on structures
• Why is competency of asset management personnel
critical?
www.dmp.wa.gov.au/ResourcesSafety
18
What is wrong with this situation?
Why is this
inappropriate?
What could
happen?
www.dmp.wa.gov.au/ResourcesSafety
19
What is wrong with this situation?
Why has this
happened?
www.dmp.wa.gov.au/ResourcesSafety
20
What is wrong with this situation?
How many
problems can
you find?
Why did this
happen?
www.dmp.wa.gov.au/ResourcesSafety
21
What is wrong with this situation?
Any guess
at the
reduction in
capacity?
Around
80%
www.dmp.wa.gov.au/ResourcesSafety
22
What is wrong with this situation?
Any guess
how long this
has been like
this?
www.dmp.wa.gov.au/ResourcesSafety
23
What is wrong with this
situation?
www.dmp.wa.gov.au/ResourcesSafety
24
What is bent and why?
www.dmp.wa.gov.au/ResourcesSafety
25
What is wrong with this situation?
www.dmp.wa.gov.au/ResourcesSafety
26
What parts of mine sites are structures?
AS 5104 (ISO 2394) General principles
on reliability for structures
2.1.1 Structure: Organized combination
of connected parts designed to provide
some measure of rigidity
2.1.2 Structural element: Physically
distinguishable part of a structure.
EXAMPLES: Column, beam, plate
2.1.3 Structural system: Load-bearing
elements of a building or civil
engineering works and the way in which
these elements function together
www.dmp.wa.gov.au/ResourcesSafety
27