Summary of research on LWC_composite column (LI_Taokui-202401).pptx

This PPT is about lightweight concrete materail test.

1. Li Taokui Dr. P.F. Men Dr. H.C. Ho Prof. K. F. Chung Constitutive modelling of light weight concrete filled steel tube(LWCFST) Jan. 2024

2. 1. Project information Title : Development of innovative high-strength lightweight concrete and composite column for low-carbon high-rise building construction Duration : 36 Months, 01-01-2024 to 31-12-2026 High-strength lightweight concrete ( MiC floor slab) Lightweight composite column (High-rise buildings) Part Ⅰ(Materials) : Prof. C.S. Poon & Dr. J.X. Lu Part Ⅱ(Structural engineering) : Prof. K.F. Chung & Dr. H.C. Ho

3. 2. Background H igh-strength lightweight composite column ( HSLCC ) A new combination form of high-strength steel ( HSS ) tube and high-strength lightweight concrete ( HSLC ) Improved ductility (overcome the brittleness of HSLC) ; Delayed local buckling with the use of HSLC ; Improved fire resistance of pure steel structure; High bearing capacity and lightweight . Advantages HSLCC HSS HSLC

4. 3. Methodology

5. 4. Main objectives To investigate the structural behavior of lightweight composite columns in the entire loading process. To investigate the confinement effect of steel tube on the infilled lightweight concrete with different swelling agent(from 0% to 12%, add 3% each time) . To investigate the constitutive model of lightweight composite columns. To investigate the bonding behavior of steel tube and the infilled concrete.

6. 5. Methodology Stage 1: Bonding behavior of CFST with different swelling agent. Specimen ID Concrete type Size of steel tube (mm) Specimen number Curing day (d) CFST-LAC-0% LAC-0% 3*152*300 1 0-28 CFST- LAC-3% LAC-3% 3*152*300 1 0-28 CFST-LAC-6% LAC-6% 3*152*300 1 0-28 CFST- LAC-9% LAC-9% 3*152*300 1 0-28 CFST- LAC-12% LAC-12% 3*152*300 1 0-28 CFST-NC-0% NC-0% 3*152*300 1 0-28 Testing scheme for the expansive stress of LAC filled steel tube columns (11/6 – 12/4)

7. 5. Methodology Stage 1: Bonding behavior of CFST with different swelling agent. LAC-0% LAC-3% LCA-6% LAC-9% LAC-12% NC-0%

8. 5. Data collection(from 8-Nov. to 5-Dec., 28 days) Vertical strain of CFST Horizontal strain of CFST

9. 5. Methodology Stage 1: Material tests on steel, concrete cubes/cylinders Stage 2: Compression tests on composite columns. Stage 3: Constitutive modelling of confined concrete and composite columns LWC60 / NC60 S235

10. 6. Test program Material tests Tensile test of steel (MS) Compression test of concrete cylinder (MC-R) S235 LWC60 / NC60 L = 300 mm D =150mm MR-C : Cube test: f cu Cylinder test: f c , E c ,& μ Longitudinal split test: f t Compression tests LWC60 / NC60 S235 D =152 mm L = 300 mm Dimensions: L/D = 300/152 = 1.97 D/t =152/3 = 50.7 Swelling agent ratio: LAC-0%, LAC-3%, LAC-6%, LAC-9%, LAC-12%, NC-0% D =146 mm

11. 6. Test program No. Spicemen Steel grade Concrete grade Swelling agent L (mm) D (mm) t (mm) N u,test (kN) 1 LAC-0-a 　 S235 LAC-60 0% 300 152 3 1511 　 2 LAC-0-b 　 S235 LAC-60 0% 300 152 3 1105 　 3 LAC-3-a 　 S235 LAC-60 3% 300 152 3 1670 4 LAC-3-b 　 S235 LAC-60 3% 300 152 3 1342 5 LAC-6-a 　 S235 LAC-60 6% 300 152 3 1677 　 6 LAC-6-b 　 S235 LAC-60 6% 300 152 3 1414 　 7 LAC-9-a S235 LAC-60 9% 300 152 3 1776 8 LAC-9-b 　 S235 LAC-60 9% 300 152 3 1656 9 LAC-12-a S235 LAC-60 12% 300 152 3 1730 10 LAC-12-b 　 S235 LAC-60 12% 300 152 3 1676 11 NC-0-a 　 S235 NC-60 0% 300 152 3 1880 12 NC-0-b 　 S235 NC-60 0% 300 152 3 1729

12. 6. Test results — Preparation LAC-0%-a LAC-3%-a LAC-6%-a LAC-9%-a LAC-12%-a NC-0%-a LAC-0%-b LAC-3%-b LAC-6%-b LAC-9%-b LAC-12%-b NC-0%-b

13. 6. Test results — Failure mode LAC-0%-a LAC-3%-a LAC-6%-a LAC-9%-a LAC-12%-a NC-0%-a LAC-0%-b LAC-3%-b LAC-6%-b LAC-9%-b LAC-12%-b NC-0%-b

14. 6. Test results — Failure mode LAC-12%-a Steel Concrete NC-0%-a Steel Concrete

15. 6. Test results — Load-Strain curve

16. 6. Test results — Load-Strain curve

17. 7. Review of constitutive modelling (Mohr-Column method)

18. Matsuoka- Nakai Mohr-Coulomb Drucker-Prager Tresca Von-Mises Soil Steel Interesting link!

19. Stress transformation Y X Z x ij where i -- direction j -- face Cauchy stress tensor

20. Direction cosine Area projection Y X Z   F F   F       F   Y X Z A x =  

21. Direction cosine Area projection Y X Z   F F   F       F   Y X Z A y =  

22. Direction cosine Area projection Y X Z   F F   F       F   Y X Z A z =  

23. Apply force equilibrium Y X Z Let cos θ x = λ x cos θ y = λ y cos θ z = λ z Write in matrix form: Apply force equilibrium, we can get:

24. Principle stresses The direction cosine may be factored: The determine of this is zero:

25. Stress invariants, isotropic and deviatoric stress components, stress path Det( - ) = 0    

26. Stress invariants, isotropic and deviatoric stress components, stress path Invariants (Don’t change with coordinate system):   = +   Cauchy stress = Isotropic stress + Deviatoric stress tensor(S d ) where = + S d   Deviatoric stress tensor :  

27. Summary of σ 1 - σ 3 relationship Researcher Research founding Considere σ 1 =α c f' c +4.8σ 3 α c ∈[1.0,1.5] Richart σ 1 = f' c +4.1 σ 3 Balmer σ 1 1.37 =196(σ 3 +430) Chinn and Zimmerman σ 1 = f' c + λ 1 σ 3 λ2 Gardner σ 1 = f' c +4.9 σ 3 Hobbs σ 1 = f' c + βσ 3 β=4.6 + 0.1 Xu Jishan( 徐积善 ) σ 1 = f' c +k σ 3 k=2e -0.125 σ 3 0.5 Avram σ 1 /f' c =1+3.7(σ 3 /f' c ) 0.86 Cai Shaohuai( 蔡绍怀 ) σ 1 /f' c =1+6.0(σ 3 /f' c ) Ansari σ 1 /f' c =1+5.5(σ 3 /f' c ) Candappa σ 1 /f' c =1+5.0(σ 3 /f' c )

28. Mohr-Coulomb  

29. Mohr-Coulomb Failure Criteria = (tan σ m + where σ m = - Mean stress tan ϕ ----------- Friction coefficient 𝜏 ------------- Cohesion strength  

30. Mohr-Coulomb Failure Criteria UCS σ 3 σ 1 σ 1 σ 3 σ 3 σ 1 σ 1 = σ 3 + UCS where σ 1 ---- vertical stress σ 3 ---- lateral stress ---- UCS - Unconfined compression strength   σ 1 σ 3 σ 3 σ 3

31. Thanks for your attention ！