1. Application of HSS microalloyed steels to a re-design of the Singapore national sports hub stadium
A presentation made for MESC 2016
April 2016, Dubai, U.A.E.
Dr Jitendra Patel - Eng.D, MBA, C.Eng MIMechE Director, International Metallurgy Ltd - UK Consultant, CBMM Technology Suisse S.A. - Switzerland

2. Contents Introduction 1 Details of the national stadium 2
Retractable roof 3
High strength steel study 4
Savings and advantages 5
Closing remarks 6
Questions

3. Introduction The new 55,000 seat National Stadium in Singapore Sports•
Hub project was completed in 2014.
• Roof structure is a highly efficient dome spanning 310m with a rise of 85m.
• The construction design was based on S355 steel using CF
CHS members with S355 HF CHS elements for thicker sections.
• Whilst serviceability issues such as deflection and fatigue were design considerations, the structure was predominately strength governed.
• This presentation summaries the finding of a study made by ARUP and CBMM that investigated any potential savings in steel that could have been made if a higher strength Nb- microalloyed steel had been used instead.

4. National Stadium Team
Architectural concept & sports venue designers: ARUP
Architect: DPA Architects
Structural Engineers: ARUP
Contractor: Dragages Singapore
Steel Contractor: Yongnam

5. National Stadium Total tonnage of the fixed roof was 7,600t•
Total tonnage of the fixed
roof was 7,600t •
Total tonnage of the
moveable roof was 1,200t •
Approx. 4,600t temporary
support was required •
Approx. 5,300 joints, on-site
full penetration butt welds •
Nearly 4,300 nodes used
on the fixed roof •
Nearly 2,000 nodes used
on the moveable roof

6. National stadium Flexibility of use; a key requirement
Football / Rugby Mode
Athletics Mode
Cricket Mode
55,00 seats
44,984 seats
49,140 seats

7. National stadium

8. National stadium - roof
Moveable roof to respond to Singapore •
climate and spectator comfort.
310m diameter spherical •
steel dome roof.
Height of 85m from pitch level. The opening is 220m x 82m. • •
A stiff fixed roof and flexible moveable structure. •

9. National stadium - roof
Fixed roof primary trusses and ring
beam.

10. National stadium - roof
Fixed roof secondary structures.

11. National stadium - roof
Largest dome roof in the world.
• Fabrication challenges: thickest section CHS 508 x 80mm
• Thickest steel element: thrust block end plates at 175mm
• Simple node: 4 to 6 brace elements meeting the primary chord
• Complex node: 7 to 10 brace elements meeting the primary chord
• Most complex node: 14 brace elements meeting at one node
• Full penetration butt welds at profiled CHS sections (6-80mm)

12. High strength steels C Mn Si S P Ni Cr Mo V Cu N Nb
CEV
S500
0.10
0.85
0.20
0.015
0.01
0.10
0.10
0.05
0.02
0.10
7ppm
0.025
0.289
BC1 Limit
0.24
0.035
0.035
0.55
Note: S, P, Ni, Cr, Mo, Cu and N are residual elements only
Grade
Yield Strength (MPa)
Tensile Strength (MPa)
Initial imperfection ratio
S355 (cold formed)
355
510
L / 260
S355 (hot finished)
355
510
L / 720
S500 (hot finished)
500
620
L / 720
• Elongation at failure >15% (25%)
• Tensile strength / Yield strength ratio >1.2 (1.24)

13. Strut buckling curves (CHS)
Maximum benefit
Most slender
for stocky members
braces

14. Relative compressive strengths compared to S355 CF CHS

15. Roof deflections Optimisation studies
Stress variation due to moveable roof - fatigue
Total dead load deflection (open roof)
Total dead load deflection (closed roof)
for S500 design
for S500 design

16. Buckling performance Grade Lcr kamp Grade Lcr S 275 6.83 1.172
Critical buckling load factor
Grade Lcr kamp S S S S
Fundamental Buckling Mode (closed roof)
Grade Lcr S S S S
Lowest Buckling Mode (compression buckling of top of chords of RWT1)

17. Summary of steel tonnage
Member
Connection
Grade
Total (t)
% saving
Mass (t)
% saving
Mass (t)
% saving
HF S275
members and
5,654
- 4 %
943
- 10 %
6,597
- 5 %
connections
CF S355
members and
5,451
0 %
861
0 %
6,312
0 %
connections
HF S375
members and
5,285
3 %
861
0 %
6,146
2.6 %
connections
S500 with
moveable roof &
4,171
23.5 %
813
- 5.6 %
4,983
21.1 %
reduced section
S690 with
moveable roof &
3,617
34 %
780
- 9 %
4,397
30 %
reduced section

18. Fatigue efficiency vs. Yield strength

19. CO2 output vs. Yield strength

20. Roof span vs. weight comparison
Breaking
new ground !

21. Summary SAVINGS ! 6,000 5,000 4,000 3,000 2,000 1,000 Tonnes
Connections
4,000
3,000
Members
2,000
1,000
CF/HF HF S355
HF S500 HF S500 HF S500
S355
Fixed & Fixed &
Moveable Roof Moveable Roof
Adjusted Library

22. 1 gram of 1.06 kg of Steel Niobium addition savings
Small investment, huge savings….
2.15t FeNb
Savings of 1,329t of steel
S500 Nb-HSS
S355 Steel
1 gram of
1.06 kg of Steel
Niobium addition
savings

23. Stadium construction

24. Acknowledgements Marcos Stuart Gustavo Macedo Tiago Costa Stuart Smith
William Whitby Marc Easton
Chelvadurai Harendran