Concrete Research at the University of Wollongong, Australia. Assoc Prof. Muhammad Hadi

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1 Concrete Research at the University of Wollongong, Australia Assoc Prof. Muhammad Hadi 1

2 2 Tim McCarthy Muhammad Hadi Alex Reminnokov Neaz Sheikh Tao Yu Shishum Zhang Lip Teh (Steel)

3 Faez Alhussainy, Hayder Alaa Hasan, Sime Rogic, M. Neaz Sheikh, Muhammad N.S. Hadi 3

4 4 Details of direct tensile test for Concrete

5 5

6 6

7 Muhammad N. S. Hadi Faez Alhussainy M. Neaz Sheikh 7

8 Steel bars are traditionally used in reinforced concrete members. In general steel bars are solid in cross section. Steel tubes that have the same cross sectional area as solid bars will have higher second moment of area and stiffness. Using steel tubes in lieu of solid bars will increase the stiffness of concrete members. Steel bars 8 Steel tubes

9 Self-Compacting Concrete is an innovative concrete that can flow and consolidate under its only weight. 9 Placement of SCC by pump tremie (Goodier, 2003) (Mott MacDonald Ltd)

10 Self-Compacting Concrete Mix proportion Type of mix EFNARC (2002) method. 10 Self-compacting concrete mix proportion Material Cement Mineral admixtures Fine aggregate Coarse aggregate Quantity/1m 3 of concrete 280 kg 170 kg 950 kg 780 kg Water 182 kg High Range Water Reducer l/ m 3 Water/Powder ratio 0.4

11 . Check fresh concrete properties with ASTM Methods Where : a) Slump flow test This test was carried out according to ASTM C1611 (2014). Calculate the slump flow (SF) according to the flowing equation: d max d perp SF 2 d max = The maximum diameter of the circular spread of the SCC. d perp = The perpendicular diameter to d max. 11 Slump flow test

12 b) J- Ring test This test was carried out according to ASTM C1621 (2014). Calculate J-Ring flow (RF) according to the following equation: RF j max j 2 perp Where: j max = The maximum diameter of the circular spread of the SCC. j perp = The perpendicular diameter to j max. Passing Ability= slump flow J-Ring flow 12 J-Ring test

13 c) Column segregation test ASTM C-1610 (2014). This test evaluates the static stability of a concrete mixture. This test consists of filling a 660 mm high cylindrical mould with concrete. (250 mm) (230 mm) (220 mm) (515 mm) (115 mm) (170 mm) (50 mm) (510 mm) 13 Detail of column mould Detail of collector plate (Based on ASTM C-1610, 2014)

14 c) Column segregation test (cont'd) Percent static segregation is calculated from equation: S% 2 CA CA B B CA CA T T 100 if CA B > CA T Where S% S % = percent static segregation. CA T = mass of coarse aggregate in the top section of the column. CA B = mass of coarse aggregate in the bottom section of the column. 0, if CA B CA T 14 Column test

15 b) Tensile testing of steel tube ASTM A370, (2014). A design that used for such plugs is shown in Figure. d d Gauge Length d 2d d d d Testing machine jaws should not extend beyond this limit d Metal plugs 15 Metal plugs for testing tubular specimens (Based on ASTM A370, 2014)

16 C) Compression testing of steel bars and tubes (a) Steel bars (b) Steel tubes 16 Compressive test of samples

17 Axial tension load-deformation curves for Specimens N12 and ST26.9 N12 ST

18 Axial tension load-deformation curves for Specimens N16 and ST33.7 ST33.7 N16 18

19 Experimental Program Group 1 Group 2 Group 3 Group 4 Group 5 19

20 Details of Tested Specimens Group No. 1 2 Specimen Labels Diameter (mm) Height (mm) N16H50C (N16) Longitudinal Reinforcement Transverse Reinforcement Loading No. of Bars or External Diameter Thickness of Tubes, Diameter of Bars Pitch (mm) Modes Tubes of Bars or Tubes (mm) (mm) % (mm) % 2.67 R Concentric N16H50E (N16) 2.67 R e = 25 mm N16H50E (N16) 2.67 R e = 50 mm N16H50F (N16) 2.67 R Flexural ST33.7H50C R Concentric ST33.7H50E R e = 25 mm ST33.7H50E R e = 50 mm ST33.7H50F R Flexural ST33.7H75C R Concentric 3 ST33.7H75E R e = 25 mm ST33.7H75E R e = 50 mm ST33.7H75F R Flexural ST26.9H50C R Concentric 4 ST26.9H50E R e = 25 mm ST26.9H50E R e = 50 mm ST26.9H50F R Flexural ST26.9H75C R Concentric 5 ST26.9H75E R e = 25 mm ST26.9H75E R e = 50 mm 20 ST26.9H75F R Flexural

21 Construction of formwork 21 Fabricated reinforcing cages

22 Strain Gauges Photo of Strain Gauge Gluing Plan View Plan View Plan View Front Elevation View Front Elevation View Front Elevation View 3D View Side Elevation View 3D View Side Elevation View 3D View Side Elevation View 22 Positions of FLA 5 Gauges for transvers reinforcement Positions of PFL 10 Gauges for longitudinal reinforcement Positions of FCA 10 Biaxial Gauges for longitudinal reinforcement

23 Before casting of specimens After casting of specimens 23

24 Loading heads 24 Four point loading method Typical set up of a column Specimen

25 Columns groups N16H50 ST33.7H50 ST26.9H50 ST33.7H75 ST26.9H75 Maximum load (kn)

26 26 Failure Modes

27 Tao Yu FRP = Fiber-Reinforced Polymer

28 axial stress (MPa) unconfined concrete Steel confined concrete FRP confined concrete axial strain

29 FRP tube 1. Corrosion-resistant skin 2. Stay-in-place formwork for casting concrete 3. Confining device for improved strength and ductility

30 FRP tube Steel tube Concrete Hybrid FRP-concrete-steel double-skin tubular structural columns (DSTCs) Excellent ductility & seismic resistance Excellent durability Ease for construction

31 Columns with a PET FRP Tube No. Specimen ID. Thickness of FRP wrap (ply) Steel tube diameter (d/mm) Steel tube thickness (t/mm) Void ratio 1 DSTC-A2-I, II 2 plies (A) DSTC-A3-I, II, III 3 plies (A) DSTC-A4-I, II 4 plies (A) DSTC-B3-I, II, III 3 plies (B) D/t 5 CFDSTC-A3-I, II 3 plies (A) N/A CFDSTC-B3-I, II 3 plies (B) N/A FCSC-2-I, II 2 plies FCSC-3-I, II 3 plies FCSC-4-I, II 4 plies CESC-A-I N/A CESC-B-I N/A FCESC-H2-I, II 2 plies Dimensions of the H-section steel column 13 FCESC-H3-I, II 3 plies b h t f t w 14 FCESC-H4-I, II 4 plies

32 Axial Load (kn) DSTC-A2-I DSTC-A3-I DSTC-A4-I Concrete Filled DSTC-A3-I Total Axial shortening (mm)

33 Axial Load (kn) CFDSTC-B3-II FCSC-3-II DSTC-B3-II CESC-B Axial Shortening (mm)

34 Near-surface mounted (NSM) fiberreinforced polymer (FRP) reinforcement: An emerging and promising technique for structural strengthening Shishum Zhang

35 Flexural Strengthening of concrete members Stirrup Stirrup Tension rebar c 1 Tension rebar bb wb t f c 2 d b h g b b h g h b h g h f h g Adhesive FRP ae Groove w g a g Groove filler w g a g wg a g wg ae Externally bonded FRP laminates Near-surface mounted FRP bars/strips Cross-section of strengthened RC beams The most important advantage of the NSM FRP method over the EB FRP method is the improved bond effectiveness between FRP and concrete, leading to a higher debonding strain of the FRP.

36 Bond between NSM FRP and concrete Establishment of the first ever 3- D meso-scale finite element model for bonded joints between a near-surface mounted (NSM) FRP strip and concrete. Positioning frame Concrete block l l b FRP strip/bar Support block Grip Rollers Bearing plate Adjustable supports Base plate Teng, J.G., Zhang, S.S., Dai, J.G. and Chen, J.F. (2013). Three-dimensional meso-scale finite element modeling of bonded joints between a near-surface mounted FRP strip and concrete. Computers & Structures, Vol. 117, pp (A* journal according to ERA ranking)

37 Bond-slip model between FRP and concrete Local bond stress (MPa) Proposed model (h_g/w_g=2.33) Proposed model (h_g/w_g=4) Proposed model (h_g/w_g=5.67) FE analysis (h_g/w_g=2.33) FE analysis (h_g/w_g=4) FE analysis (h_g/w_g=5.67) 2B s A( ) B A 0.72 fc G f B 0.37 f c fc 2B s sin( ) 2 B Slip (mm) max f c Formulation of the first accurate bond-slip model for CFRP strips near-surface mounted to concrete. Can be : 1) used to establish the bond strength model of NSM CFRP strip-toconcrete bonded joints; and 2) incorporated into FE models of RC structures strengthened with CFRP strips to simulate the debonding failure process. Zhang, S.S., Teng, J.G., Yu, T. (2013). Bond-slip model for CFRP strips near-surface mounted to concrete. Engineering Structures, Vol. 56, pp (A* journal according to ERA ranking)

38 Bond strength model between FRP and concrete FRP element cohesive element P Average=0.924 STD=0.109 CoV=0.118 P P L e 2G E A C u f f f failure 2G E A C u L f f f failure C max 2G E f failure f A f Test bond strength (kn) < and 5.67 > Prediction of the proposed model Work done before joining UOW: Development of a bond strength model for NSM CFRP strip-toconcrete bonded joints, which is the first model that can accurately account for the effect of bond length on bond strength Zhang, S.S., Teng, J.G., and Yu, T. (2014). Bond strength model for CFRP strips near-surface mounted to concrete. Journal of Composites for Construction, ASCE, in press. (A journal according to ERA ranking)

39 FE modelling of NSM FRP-Strengthened RC beams Test FE prediction Work done before joining UOW: Development of an accurate finite element model for predicting end cover separation failures in RC beams strengthened with FRP in flexure Zhang, S.S. and Teng, J.G. (2014). Finite element analysis of end cover separation in RC beams strengthened in flexure with FRP, Engineering Structures, Vol. 75, pp (A* journal according to ERA ranking)

40 Simplified FE model for debonding failure Development of an accurate simplified finite element model Zhang, S.S. and Teng, J.G. (2015). End cover separation in RC beams strengthened in flexure with bonded FRP reinforcement: simplified finite element approach, Materials and Structures, 49 (6),

41 Strength model for debonding failure in strengthened concrete beams separation. 6 3 R cs P if R P if cs AE 4.5 c ( s s AE b / Db cl ear 0 P sc )( c c A E f f P 0.08) f c ε db from Simplified FE model (με) Average: 1.00 STD: CoV: b D t 0 b.85 clear Dt ε db from proposed model (με) Establishment of an accurate strength model for end cover separation failures in RC beams strengthened with FRP in flexure Teng J.G., Zhang S.S. and Chen J.F. (2015). Strength Model for End Cover Separation Failure in RC Beams Strengthened with Near-surface Mounted (NSM) FRP Strips, submitted to Engineering Structures, under review. (A* journal according to ERA ranking)

42 Analytical solution to interaction forces between NSM FRP and beam Analytical and numerical investigations on the prediction of interaction forces in beams strengthened with near-surface mounted FRP bars. Zhang, S.S. and Yu T. (2015). Analytical solution for interaction forces in beams strengthened with near-surface mounted round bars, submitted to Construction and Building materials, under review. (A journal according to ERA ranking) 0 ) ( ) ( 1 1 ) ( x V I E I E d k x F A E A E I E I E d k dx x F d T f f b b f b l l f f b b f f b b f b l l 0 1 ) ( ) ( 1 1 ) ( 4 4 q I E k dx x df I E y I E y k x F I E I E k dx x F d b b v l f f f b b b v v f f b b v v Tangential interaction force (N / mm) Distance from the NSM bar end (mm) FE model Present method Normal interaction force (N / mm) Distance from the NSM bar end (mm) FE model Present method

43 Novel FRP anchorage system

44 Novel FRP anchorage system Adjacent concrete wall GFRP anchor GFRP sheets Optical fibers with FBG sensors (to Optical Sensing Interrogator )

45 Novel FRP anchorage system Tensile tests 9000 Microstrain FBG Strain guage 1500 Bond tests Load (kn)

46 Novel FRP anchorage system Slab tests Root moment (kn*m) SS-1 SS-2 Unstrengthened SS-2: 17.5 kn*m Unstrengthened SS-1: 15.3 kn*m Free end deflection(mm) Microstrain FBG-L-1 FBG-L-2 FBG-R-1 FBG-R-2 Microstrain FBG-L-3 FBG-L-4 Strain guage Microstrain FBG-R-3 FBG-R-4 Strain guage Root Moment (kn*m) Root moment (kn*m) Root moment (kn*m)

47 Other projects

48 Fiber-optic monitoring of FRP-strengthened RC slabs Fiber-optic monitoring of underground jacking pipes Alkaline Resistance of GFRP Bars Smart FRP bars

49 49