Steel Compliance from the Consulting Engineer's Perspective

Steel Compliance –
The Consulting
Engineers’
Perspective
Mark Sheldon
Technical Director
October 2015

2
The Compliance of Steelwork in Buildings
from the Design Engineer’s viewpoint
What does a consulting engineer do
What doesn’t a consulting engineer do
3 Case Studies

3
Offices: 87
Countries: 28
Employees: 7,000+

4
Mark Sheldon – Technical Director, Structural Engineer
• Melbourne Park - Project Director for Margaret Court Arena
• Project Director for Simonds Stadium (35,000 seats) – stages 1,2,3 & 4
• Cebu Seaside Arena (Concept design for 10,000 seat arena in the
Philippines)
• Melbourne Park – Technical Advisor role for National Tennis Centre
• Structural Design Leader for Perth Arena (14,000 seats)
• MCG Redevelopment (101,000 seats) Design Team Leader
• Etihad Stadium (54,000 seats) Structural Design Team Leader
• Roof Structure Design Team Leader for 10,000 seat Hisense Arena (incl
retractable roof)
• Design Team Leader for concept of 34,000 seat TEDA Soccer Stadium,
Tianjin
• Eden Park redevelopment (NZ) concepts and peer review
• Team Leader for Delhi 2010 Commonwealth Games Siri Fort and Yamuna
Sports Complexes
• MSAC Design Team Leader (Approx 300m x 80m sports indoor complex)
• Peer Reviewer for Wembley National Stadium, UK
• Designer for 44,000 seat Great Southern Stand, MCG
• Specialist input on dynamics - Kuala Lumpur Convention Centre

5
Analysis
• Spacegass
What Does a Structural Engineer do ?

6
Analysis
• Spacegass
• ETABS

7
Analysis
• Spacegass
• ETABS
• Rhino/Grasshopper

8
Analysis
• Spacegass
• ETABS
• Strand 7

9
Analysis
• Spacegass
• ETABS
• Rhino/G’hopper
• Strand 7
• Dynamo
• RAPT
• RAM Concept
• Robot
• GSA
• etc

10
Design and Detailing
• Determine stresses in members
• Select reo size or steel section

11
AS4100 states that members and connections shall be
proportioned so that:
∗
Where:
S* is the design action effect
Ø is the capacity factor
Ru is the nominal section or member capacity
Limit state design philosophy

12
Capacity factor () accounts for:
 Variations in material properties
 Section and member dimensional tolerances
 Fabrication and construction tolerances
 Structural modelling inaccuracies
 Ductility and reliability requirements
Load factors account for variability of load effects

13
ProbabilityProbabilityProbability
Design load effect = Nominal (characteristic) load effect x load factor
Nominal load effect Design load effect
Load effect
Capacity
Design capacity = Nominal (characteristic) capacity x capacity factor
Design capacity Nominal (characteristic) capacity
Probability of failure (shaded area) ~ 0.001
95thPercentile
5thPercentile

14

15

16
Analysis
• Spacegass
• ETABS
• Strand 7
• Dynamo
• RAPT
• RAM Concept
• Robot
• GSA
• etc
• Revit

17
2D documentation and detailing

18
What Doesn’t a Structural Engineer do ?
Metallurgy
Chemistry
Forensics

19
Procurement of Construction Products

20
Procurement of Construction Products

21
AS4100
 ≤ 0.9
Erection
AS 4100
Welding
AS 1554
Fabrication
AS 4100
Testing
AS 1391
AS 1554
AS 3678
Material supply
AS 1163 – Hollow Sections
AS 3678 – Plate
AS 3679 – Open Sections
Australian Standards for steel design have been calibrated for Australian
manufactured steels using a suite of Australian Standards. The designer
assumes that the material being used on site meets these standards.

22
The fine print: -

23
The fine print: -

24
The fine print: -

25
The fine print: -

26
The fine print: -

27
The fine print: -

28
The fine print: -

29
The fine print: -

30
Project details
 Australian steel specified
The problem
 Large hollow sections sourced from offshore
 Mill certificates provided in Chinese, but incomplete
 Chemical limit exceeded (apparently)
The outcome
 NATA certified testing performed in Australia
 Metallurgist consulted
 Chemical composition compliant (typo on sheets)
 Mechanical properties compliant
 Steelwork accepted
Project A – Large Building Structure

31
Project details
 Australian steel specified
The problem
 Non-compliant steel plate identified after site erection completed
 Plate sourced from overseas had yield strength less than specified
 Lack of traceability – could not establish which connections were affected
The outcome
 NATA certified testing performed in Australia
 Actual yield strength determined
 Weldability was deemed to be acceptable
 Risk based assessment – connections involving affected plate were not utilised 100%
 Plate accepted (slight increase risk of failure)
Project B – Large Building Structure

32
Project details
 ~$2 billion port expansion project
 20,000t marine steelwork / 10,000t structural steelwork
 Steel procured and fabricated in China
The problem
 Potential steel non-compliance
 Preliminary design completed to Australian Standards
The outcome
 Gap analysis between Australian and Chinese standards
 Compliance testing performed in Australia
 Design capacity adjustment
Project C – Port expansion

33
Pros
 Potential cost savings ~$50m:
o Local fabrication ~ $5,000-$7,000/t
o Chinese fabrication ~ $2,000/t
o Fabrication only (excludes transport)
 Potential schedule gains due to
increased production rates
Cons
 Procurement issues: currency
variation, greater transport and logistic
considerations and costs
 Quality concerns and subsequent
increased QA requirements
 Increased schedule risk due to
additional QA and/or rejected material
 Increased technical/ design
considerations
 Increased steel tonnage due to
member substitution after preliminary
design (~8% total)
Pros and cons of using foreign steel

34
Chemical composition
Mechanical properties
Dimensional tolerances
Manufacturing process
Material Supply
AS/NZS 1163 Structural steel hollow sections
AS/NZS 1594 Hot‐rolled steel flat products
AS/NZS 3678 Structural steel – hot rolled plates…
AS/NZS 3679 Structural Steel:
Part 1 – Hot‐rolled bars and sections
Part 2 ‐ Welded sections




Australian Standards

35
Following the gap analysis, supply tolerances remained non-
compliant (including angle leg thickness, depth of section).
Options considered:
 Relax tolerances to Chinese limits and reduce capacity factor; or
 Reject all steel that does not comply
Reduction in capacity factors chosen as preferred method to mitigate
procurement issues and schedule delays, and maintain similar
probability of failure.
Dealing with non-compliance

36
Capacities found for:
− Smallest geometry permissible by
Australian Standards
− Smallest geometry permissible by
Chinese Standards
% decrease in capacity calculated
Used as % decrease in Capacity Factor
Assessment undertaken for various
sections and lengths
Reduction of capacity factors

37
Steel section Capacity factor ()
RHS / SHS 0.85
TFC 0.88
EA / UA 0.80
CHS 0.81
All other sections 0.90
New capacity reduction factors

38
Probability
Design load effect
Load effect and capacity
Design capacity (Australian steel)
Probability of failure (Australian steel)
Probability of failure (Chinese steel)
Design capacity (Chinese steel)
Probability of load effect and capacity

39
What Does this all mean ?
Non-compliant steelwork can cause real problems such as:
 Material rejection and rework
 Project delays
 Redesign
 Increased risk of structural failure
 Insurance claims and litigation
Design documents state that materials must comply with Australian
Standards, and the onus is on the Supplier/Contractor to satisfy this
requirement.
The design engineer won’t spend hours checking the validity and traceability
of the certificates. Structural engineers are not metallurgists.
Third-party certification by a reputable organisation is a wise investment

Steel Compliance from the Consulting Engineer's Perspective

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