Hiap Teck Venture Bhd. · MYX:HIAPTEK

Hiap Teck Venture Bhd — Technical Presentation (February 2017)

56 slides from Hiap Teck Venture Bhd's technical presentation, Feb 23, 2017

  1. Slide 1: Some Design Issues with Selection of Steel Materials

    SOME DESIGN ISSUES WITH SELECTION OF STEEL MATERIALS Chiew Sing Ping Professor and Programme Director of Civil Engineering SINGAPORE INSTITUTE OF TECHNOLOGY 23 February 2017

  2. Slide 2: Presentation Outline

    Presentation Outline • High Strength Steel = Construction Productivity - Normal Strength (≤460 N/mm2) vs. High Strength (≥460 N/mm2) Structural Steel - Structural Steel vs. Reinforcing Steel • Current Design Issues in using High Strength Reinforcing Bars in EC2 • Current Design Issues in using High

  3. Slide 3: High Strength Steel = Construction Productivity

    High Strength Steel = Construction Productivity

  4. Slide 4: Replacing NSS with HSS

    Replacing NSS with HSS Construction Total material Uncertain performance Strength/weight ratio Productivity

  5. Slide 5: Benefit of using HSS: Fabrication Cost

    Benefit of using HSS Example for built-up box section Fabrication Cost Weight of Steel Weight Material & Maximization Fabrication Cost of Benefit Strength S460 !

  6. Slide 6: Structural Steel: S690 vs. S355

    Structural Steel: S690 vs. S355 900 RQT-S690 800 700 Hot-formed S355 600 Strength 100% 500 Stress (MPa) 400 300 200 Ductility 100% 100 0 0 5 10 15 20 25 30 35 Strain (%) C Mn Cu P S Al Ti Si Cr Mo V Ni B CE S355 0.15 1.33 0.032 0.031 0.009 0.044 <0.001 0.34 0.032 0.008 0.006 0.023 - 0.41 RQT- 0.14 1

  7. Slide 7: Manufacturing of Structural Steel

    Manufacturing of Structural Steel

  8. Slide 8: High Performance Steel Plates

    High Performance Steel Plates

  9. Slide 9: Effect of Heat Treatment

    Effect of Heat Treatment SiT paw TECHNOLOGY good Toughness Strength high

  10. Slide 10: Structural Steel vs. Reinforcing Steel

    Structural Steel vs. Reinforcing Steel Trend is towards use of higher grade but more stringent ductility requirements in terms of tensile/yield strength ratio and elongation. Reinforcing Steel Structural Steel A B C Normal strength High strength Yield strength ≥ 460 400 to 600 ≤ 460 (MPa) ≤ 690 Modu

  11. Slide 11: Material Comparison in Eurocodes

    Material Comparison in Eurocodes EC2 EC3 EC4 Normal C12/15- C90/105 C20/25 - C60/75 Concrete _ Light LC12/13 – LC80/88 LC20/22 - LC60/66 weight Reinforcing steel 400 - 600 N/mm2 _ 400 - 600 N/mm2 Structural steel _ ≤ 690 N/mm2 ≤ 460 N/mm2 Same trend towards use of higher grade concrete, leads to gre

  12. Slide 12: Current Design Issues in using High Strength Steel Reinforcing Bars in EC2

    Current Design Issues in using High Strength Steel Reinforcing Bars in EC2

  13. Slide 13: Steel Rebars (from SS2 to SS560)

    Steel Rebars (from SS2 to SS560) Mechanical Properties Standard Grade Yield strength Tensile/yield Elongation at Elongation at Re (MPa) strength ratio, Rm/Re fracture A5 % maximum force, Agt % SS2: 1987 460 460 1.15 12 - SS2: 1999 500 500 1.05 14 - B500A 500 1.05 - 2.5 B500B 500 1.08 - 5.0 B500C 500

  14. Slide 14: Benefits of Grade 600 Rebar

    Benefits of Grade 600 Rebar Item Description Potential to reduce steel reinforcement – up to 20% compared to current Steel Saving Grade 500 rebar Steel Fabrication Up to 20% less workers are needed Logistics Less trucks carrying steel reinforcement on the roads – up to 20% less Handles up to 20% les

  15. Slide 15: Benefits of Grade 600 Rebar

    Benefits of Grade 600 Rebar ? 20 % saving Cross-section: 1100mm x 1100mm Cross-section: 1100mm x 1100mm Rebar: Grade 500 Rebar: Grade 600 Concrete: C50/60 Concrete: C50/60 Longitudinal rebar: 32 Φ25 Longitudinal rebar: 24 Φ25 15

  16. Slide 16: Benefits of Grade 600 Rebar

    Benefits of Grade 600 Rebar ? Rebar: 20 % saving Concrete: 33% saving Cross-section: 1100mm x 1100mm Cross-section: 900mm x 900mm Rebar: Grade 500 Rebar: Grade 600 Concrete: C50/60 Concrete: C90/105 Longitudinal rebar: 32 Φ25 Longitudinal rebar: 24 Φ25 16

  17. Slide 17: But how to achieve these savings?

    But how to achieve these savings …?

  18. Slide 18: Design Provisions in EC2

    Design Provisions in EC2 Stress-strain relationships Three types are allowed in SS EN1992-1-1, i.e. • Parabolic-rectangular diagram • Bi-linear stress-strain diagram • Rectangular diagram 18

  19. Slide 19: Design Provisions in EC2

    Design Provisions in EC2 Concrete compression strain  In design, failure of concrete in compression is defined by means of limiting compressive strains.  EN1992-1-1 adopts a limit of εcu2 (or εcu3 if bi-linear diagram is used) for flexural, a limit of εc2 or εc3 for pure axial compression, and a i

  20. Slide 20: Strain Compatibility

    Strain Compatibility When high strength steel rebar is used in RC column, there is much concern about early concrete crushing; when the yield strain of the steel exceeds the crushing strain of concrete (generally, εc = 0.002 (≤C50/60) for pure compression), concrete crushing occurs before yielding o

  21. Slide 21: Axially Loaded Columns

    Axially Loaded Columns The maximum pure compressive strain is εc2 or εc3 when the whole section is under pure compression. εc2 η fcd εsc σsc σsc Cross-section strain stress Limiting Concrete Strain & Maximum Strength of Grade 600 Rebar Grade εc2 εc3 f y,εc2 f y,εc3 ≤ C50/60 0.0020 0.00175 460 403 C5

  22. Slide 22: Columns under Compression and Bending

    Columns under Compression and Bending The maximum compressive strain is assumed to lie between εc2 (or εc3) and εcu when the section is in compression and bending. c2 = 0.002 εc2 x/(x-3h/7) εcu = 0.0035 εcu = 0.0035 εsc h x x (a) Pure compression (b) x > h (c) x = h (d) x < h N A For case (a) and (

  23. Slide 23: Confined Concrete Strain

    Confined Concrete Strain Confinement can be generated by adequately closed hoops or links. This results in higher strength and higher critical strain. SS EN1992-1-1 Clause 3.1.9 fck,c  fck 1.0  5.0  2 f ck  for  2  0.05 f ck fck,c  fck 1.125  2.5 2 fck  for  2  0.05 fck  c2,c   c2 

  24. Slide 24: Confined Concrete Models

    Confined Concrete Models The confinement depends on many factors including • The diameter, layout, spacing and number of the longitudinal reinforcement bars • The diameter and spacing of the transverse reinforcement bars • Yield stresses of the reinforcement bars • Concrete strength Various confinem

  25. Slide 25: Concrete Confinement

    Concrete Confinement The confining pressure provided by lateral hoops or links results in an enhancement in the strength and ductility of the concrete. If the concrete is well confined, the full yield strength of the steel reinforcing bar may be developed by the increased strain of the confined conc

  26. Slide 26: Concrete Confinement

    Concrete Confinement 500 620 Link Spacing s (mm) 400 600 fy,εc2,c (N/mm2) 580 300 fyk= 600 MPa , Φ12 560 200 fyk= 600 MPa , Φ10 540 fyk= 600 MPa , Φ10 100 520 fyk= 500 MPa , Φ10 0 500 0.002 26 0.0025 0.003 0.0035 0.004 0 200 400 600 Link Spacing s (mm) Strain εc2,c 26

  27. Slide 27: Concrete Confinement

    Concrete Confinement 60000 Grade 600; σ2/fck =0.025 50000 Grade 600; σ2/fck =0 40000 N (kN) 30000 Grade 500; σ2/fck =0 20000 10000 0 0 2000 4000 6000 8000 10000 M (kNm) 27

  28. Slide 28: Current Design Issues in using High Strength SRC Columns in EC4

    Current Design Issues in using High Strength Steel Reinforced Concrete (SRC) Columns in EC4

  29. Slide 29: Composite Columns in EC4

    Composite Columns in EC4 Steel: Composite Columns: High Strength • Achieve overall enhancement High Ductility in strength and stiffness • Provide fire-protection and Concrete: buckling resistance for steel Lower Cost section Good Fire Resistance SRC CFT

  30. Slide 30: Limitation of Design Codes

    Limitation of Design Codes Codes Steel yield strength Concrete cylinder strength (N/mm2) (N/mm2) EC4 235 ~ 460 20 ~ 60 EC2 - 12 ~ 90 EC3 235 ~ 690 - The ranges in EC4 are more restricted than EC2 and EC3, the question is WHY? • Lack of test data and experience in designing composite members with hig

  31. Slide 31: Concrete Filled Tubular (CFT) Columns

    Concrete Filled Tubular (CFT) Columns Concrete Filled Tubular Columns with High Strength Materials - An Extension of Eurocode 4 Method to C90/105 Concrete and S550 Steel Took advantage of concrete confinement provided by the outer steel tube and validated against test database ! Question: what about

  32. Slide 32: Existing Test Data of SRC Columns

    Existing Test Data of SRC Columns Distribution of fy for SRC column tests Distribution of fc for SRC column tests Test data is insufficient to establish the validity of using high strength materials in SRC columns.

  33. Slide 33: Comparison Study

    Comparison Study  SRC columns with normal strength materials (≤ S460) (fc ≤ 50 MPa and fy ≤ 460 MPa) Test/EC4 Code Conservative Mean Value 1.21 Safe !  SRC columns with high strength materials (≥ S460) (fc > 50 MPa and fy > 460 MPa) Code Overestimates Test/EC4 Test Results Mean Value 0.87 Not Safe

  34. Slide 34: Why Not Safe?

    Why Not Safe? • Much concern about early concrete crushing in SRC columns with high strength steel. • If the yield strain of the steel exceeds the crushing strain of concrete, concrete crushing occurs before yielding of the steel – ‘strain compatibility’. • High strength steel cannot develop its ful

  35. Slide 35: Strain Compatibility Method

    Strain Compatibility Method Maximum Strength of Steel before Concrete Crushes Grade S235 S275 S355 S420 S460 S500 S550 S620 S690 ≤ C50/60 235 275 355 420 420 420 420 420 420 C55/67 235 275 355 420 460 464 464 464 464 C60/75 235 275 355 420 460 483 483 483 483 C70/85 235 275 355 420 460 500 504 504 5

  36. Slide 36: Confined Concrete Method

    Confined Concrete Method Confinement can be provided by closed hoops or lateral links. The confining pressure results in higher strength and higher strain of the concrete. The confinement depends on many factors • The diameter, layout, spacing and number of the longitudinal reinforcement bars • The

  37. Slide 37: Confined Concrete Method

    Confined Concrete Method • For SRC columns, confinement can be provided by the lateral links and steel section. • Eurocodes only provides the stress-strain relationship of confined concrete in RC columns. • How to predict the stress-strain behaviour of confined concrete in SRC columns? Confinement z

  38. Slide 38: Confined Concrete Method

    Confined Concrete Method EN1992-1-1 Clause 3.1.9 fck,c  fck 1.0  5.0  2 f ck  for  2  0.05 f ck fck,c  fck 1.125  2.5 2 fck  for  2  0.05 fck  c2,c   c2  fck,c fck  2  cu2,c   cu2  0.2  2 fck The effective lateral compressive strength due to confinement σ2:  2 fck  0.5wd

  39. Slide 39: Comparison Study

    Comparison Study Comparison of test data and codes on SRC columns with high strength materials Test/EC4 Test/EC4,u Test/EC4,c Mean 0.87 1.11 0.94 EC4 is the resistance by EC4 plastic method; EC4,u is the resistance by EC4 considering strain-compatibility; EC4,c is the resistance by EC4 considering s

  40. Slide 40: Current Restrictions in Extension of Existing Design Rules up to Grade S690 in EC3-1-12

    Current Restrictions in Extension of Existing Design Rules up to Grade S690 in EC3-1-12

  41. Slide 41: Intensification of Low-Density Developments: Functional Bridging Buildings

    Intensification of Low-Density Developments: Functional Bridging Buildings MNDRF SUL2013-4 Combined S690 + S355 Only S355 Weight/m2= 311 kg/m2 (Grade S690) Weight/m2= - + 150 kg/m2 (Grade S355) + 896 kg/m2 (Grade S355) + 22 kg/m2 (Y1860S7 15mm) + 22 kg/m2 (Y1860S7 15mm)

  42. Slide 42: Submerged Arc Welding (SAW)

    Submerged Arc Welding (SAW) SiT| Welding direction of SAW : perpendicular to column longitudinal << Welding direction _ | SINGAPORE INSTITUTE OF TECHNOLOGY + Feed the welding wire into the flux supplied ahead of welding wires. - Large current. multiple electrodes > High work efficiency

  43. Slide 43: Electro-Slag Welding (ESW)

    Electro-Slag Welding (ESW) SiT paw Welding direction of ESW : perpendicular to column longitudinal Welding wire Backing plate + Feed the welding wire into molten slag > Welding wire and base metal melt due to resistance heating of slag * Upward welding

  44. Slide 44: Heat Input & Size of HAZ – Productivity

    Heat Input & Size of HAZ – Productivity

  45. Slide 45: Heat Input for Various Welding Process

    Heat Input for Various Welding Process

  46. Slide 46: Possible Effects of Welding

    Possible Effects of Welding 1. HAZ: Mechanical property alteration including strength, toughness and ductility 2. High residual stress caused by thermal expansion & contraction and phase transformation 3. Distortion Influences of residual stress Compression: Failures due to instability HAZ by high h

  47. Slide 47: EN1993-1-12: Extension to S690

    EN1993-1-12: Extension to S690 ADDITIONAL RULES TO EN 1993-1-8  Angles connected by one leg and other unsymmetrically connected members in tension: Eccentricity must be considered  Rules for Lug angles are not applicable  Rules for Resistance of welded connections for under matched welding electr

  48. Slide 48: Compression Tests on S690 Columns

    Compression Tests on S690 Columns Concentrically loaded columns: Back analysis to EN 1993-1 Loading procedure: Pre-loading: up to 10% predicted resistance Loading application: 1. Initially, use load control: ≈ 10 N/mm2 per minute 2. When approaching 80% of the predicted resistance, use displacement

  49. Slide 49: Column Test Results

    Column Test Results Test C3S series Test C4PA 1.1 Test C3PA Test C4QA Test C1S series Test C2PA 1.0 0.9 Test C2S series 0.8 Test C3QA Reduction factor χ 0.7 Test C1PA Curve a0 Test C2QA 0.6 0.5 0.4 0.3 Curve c 0.2 0.1 0.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 Non-dimensional slenderness, λ  C

  50. Slide 50: Equivalent T-Stub Joint

    Equivalent T-Stub Joint Why model and test simple T-Stub Joint? Plastification failure – Formation of Plastic Hinge at Weld Toe F HAZ at Weld Toe M1 θ M2 δ θ tf m m Deformation of the T-stub joint (Mode 1)

  51. Slide 51: Effect of HAZ

    Effect of HAZ Displacement load EN1993-1-8 Design plastic resistance (Component/Yield line Method) 4𝑀𝑝𝑙 ,1,𝑅𝑑 1 𝐹= Eqn. (1) 𝑚 (8𝑛 − 2𝑒𝑤 )𝑀𝑝𝑙 ,1,𝑅𝑑 1 𝐹= Eqn. (2) 2𝑚𝑛 − 𝑒𝑤 (𝑚 + 𝑛) Load carrying Note: Eqn. (2) takes the effect of washer F capacity is fully and bolt heat into…

  52. Slide 52: Reduction Factor for Plastic Resistance

    Reduction Factor for Plastic Resistance Modified first yield resistance 𝑤𝑡 𝑏ℎ 2𝑀𝑝𝑙 ,1,𝑅𝑑 + 2𝑀𝑝𝑙 ,1,𝑅𝑑 4(𝐻𝐴𝑍 )𝑀𝑝𝑙 ,1,𝑅𝑑 1 𝐹= = Eqn. (3) 𝑚 𝑚 𝑤𝑡 𝑏ℎ (8𝑛 − 2𝑒𝑤 )(2𝑀𝑝𝑙 ,1,𝑅𝑑 + 2𝑀𝑝𝑙 ,1,𝑅𝑑 )/4 (8𝑛 − 2𝑒𝑤 )(𝐻𝐴𝑍 )𝑀𝑝𝑙 ,1,𝑅𝑑 1 𝐹= = Eqn. (4) 2𝑚𝑛 − 𝑒𝑤 (𝑚…

  53. Slide 53: How to obtain Reduction Factor

    How to obtain Reduction Factor 𝐻𝐴𝑍 Case 1: 𝑑𝐻𝐴𝑍 is smaller than the depth of the PNA (usual case) 1 𝑑𝐻𝐴𝑍 + 𝑑1 + 𝑑2 = 𝑡 𝑡/2 1 𝜎𝑑𝑦 = 𝑓𝑦 ,𝐻𝐴𝑍 𝑑𝐻𝐴𝑍 + 𝑓𝑦 𝑑1 − 𝑓𝑦 𝑑2 = 0 −𝑡/2 𝑤𝑡 𝑡/2 𝑓𝑦 𝑑22 + 𝑑12 𝑑𝐻𝐴𝑍 1 𝑀𝑝𝑙 ,1,𝑅𝑑 = 𝜎𝑦𝑑𝑦 = 𝑙𝑒𝑓𝑓 [ + 𝑓𝑦 ,𝐻𝐴𝑍…

  54. Slide 54: Results and Parametric Study

    Results and Parametric Study HAZ Test average (kN) Eqn. 3 (kN) Eqn. 4 (kN) Diff 3 (%) Diff 4 (%) 0.957 201.3 215.9 8.6 1.3 218.7 0.842 177.2 190.0 23.4 15.1 Note: Better results can be obtained if the evaluation of the mechanical properties of HAZ is more precise LOW HEAT INPUT WELDING (e.g. SMAW,

  55. Slide 55: Conclusions

    Conclusions EC2 EC3 EC4 Normal C12/15- C90/105 C20/25 - C60/75 Concrete _ Light LC12/13 – LC80/88 LC20/22 - LC60/66 weight Reinforcing steel 400 - 600 N/mm2 _ 400 - 600 N/mm2 Structural steel _ ≤ 690 N/mm2 ≤ 460 N/mm2 1. Work is in progress to extend the current limitation of high strength GR600 ste

  56. Slide 56: Thank you!

    Thank you !

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