FRP FOR SUSTAINABLE PRECAST CONCRETE STRUCTURES

Transcription

1 FRP FOR SUSTAINABLE PRECAST CONCRETE STRUCTURES Sami Rizkalla North Carolina State University October 21-22,

2 Underground Precast Utility Tanks 2

3 1993 Beddington Trail Bridge First Bulb-Tee bridge girder pretensioned with CFRP tendons 3 No signs of degradation when tested in July 2008, after 15 years of service

4 1997 Taylor Bridge First AASHTO Girder prestressed and Reinforced with CFRP CFRP stirrups 4 Instrumentation of the girder before casting Route 40 Bridge, Virginia

5 CFFT Piles 700 load (kn) Confinement effect + Bending Resistance strain (me) Axial Resistance 5

6 Power line poles 5.8 t 12 t 6

7 Recent Innovation for Precast Concrete Products Double-Tee beams Wall Panels Composite Non-composite Architectural Cladding 7

8 Corrosion Free Double-Tee Thin flange susceptible to chloride penetration CFRP Grid replacement for WWF conventional steel 8

9 Carbon Fiber Grids Carbon grids are manufactured in an automated process: High production volume High quality control 9

10 Pre-topped Double Tees 10 10

11 Pre-topped Double Tees 11

12 Carbon Fiber Installation - Embedment and finishing machine to place the grid - More precisely for optimum performance - More consistent; less opportunity for human error 12

13 Research and Development at NC State Uniformly distributed applied load Experimental Program 13

14 Testing Program 14

15 Testing Program 15

16 Testing Program 16

17 Testing Program Initial Cracking: 17 DT1 DT2

18 Results Failure Mode DT1 2 thick flange 18

19 Results Failure Mode DT1 2 thick flange 19

20 Results Failure Mode DT2 3.5 thick flange 20

21 Results 2 thick flange Midspan Measured Vertical Deflection (in.) Distance along DT Profile (ft.) 3.5 thick flange Midspan Measured Vertical Deflection (in.) Ultimate Service Factored Distance along DT Profile (ft.) Ultimate Service Factored

22 Concentrated Load Test 22 Failure load = 11,300 lbs

23 Summary C-GRID is effective transverse flange reinforcement for precast concrete Double-Tees. The concentrated load carrying capacity satisfies PCI requirement. 23

24 Recent Innovation for Precast Concrete Products Double-Tee beams Wall Panels Composite Non-composite Architectural Cladding 24

25 Prestressed Concrete Sandwich Load Bearing Panels - Resist vertical and lateral loads - Provide building envelope - Consists of two concrete wythes and a layer of rigid foam. - Composite action achieved by shear connectors 25

26 Composite Action & Shear Connection Available FRP shear connectors Discrete 26 Continuous

27 Insulated Sandwich Panel Orthogonal CFRP Grid Cut at a 45-degree angle to develop truss action Structurally and thermally efficient 27

28 Insulated Sandwich Panel Wythe Reinforcement Exterior Interior Pilaster Typical Cross Section Carbon Fiber Shear Connector Carbon fiber grid shear connectors: - Provide composite action between wythes - Increase insulation value due to low thermal conductivity of the connector 28 28

29 Experimental Program At NCSU 29

30 Overall Panel Behavior Composite Lateral Deflection (cm) Lateral Load (lbs) Ultimate Load Representative EPS Panel Lateral Load (kn) 5000 Service Load 22 Non-composite Lateral Deflection (in)

31 Degree of Shear Connection 31

32 Experimental Results EPS D+0.5L r +1.6W 150

33 Failure Modes Flexural-shear failure Panel Separation 33

34 42 foot panel tests 34

35 Analysis Theoretical composite and noncomposite load-deflection relationships were calculated following PCI guidelines. Percent composite action was determined based on deflections as follows: Calculation of I eff for non-composite behavior ACI I eff M = M cr a 3 I g M + 1 M cr a 3 I Valid only for I g /I cr < 3.0 cr I g 35 κ (%) = nc c exp x nc 100 Bischoff and Scanlon (2007) I eff = M 1 M cr a I cr 2 1 I I cr g I g

36 Partial Interaction Theory κ FAt the given curvature (%) = x100 F At the full compsoite action M u = M I + M O + F Z 36

37 Finite Element Analysis CFRP grid 5.5 in. (140 mm) spacing CFRP grid 3.5 in. (89 mm) spacing 8-Node solid elements for foam and concrete 37 Truss elements for C-Grid

38 Results Strain distribution for EPS2 Panel at service load Inner wythe Compression Panel Thickness (in) Panel Thickness (mm) Tension Experimental Rational model FEA Outer wythe Outer wythe Strain x 10 6

39 Extreme Events 39 Fire testing

40 GFRP Truss Connector 40

41 GFRP Truss Connector 41

42 42

43 Summary FRP can provide shear transfer mechanism without thermal breaks in precast prestressed concrete sandwich panels. Simple rational design approach can be used to determine degree of composite action 43

44 Recent Innovation for Precast Concrete Products Double-Tee beams Wall Panels Composite Non-composite Architectural Cladding 44

45 Non-Composite Sandwich Panel FRP Connector: 45 Composite Panel Non-composite Panel

46 Thermo graphic image showing: 46 Thermal bridging NO thermal bridging

47 Recent Innovation for Precast Concrete Products Double-Tee beams Wall Panels Composite Non-composite Architectural Cladding 47

48 Insulated Architectural Panel Vertical Back Ribs 48 Intermediate ribs attached to architectural façade with CFRP grid to avoid discoloration or shadowing

49 Insulated Architectural Panel Horizontal Back Ribs 49 Intermediate ribs attached to architectural façade with CFRP grid to avoid discoloration or shadowing

50 Panel Configuration Primary vertical rib 50 Secondary vertical rib 6 Typical Carbon fiber grid in the panel face for crack control

51 Manufacturing Process 51 Placement of CFRP grid reinforcement for architectural facade

52 Manufacturing Process Foam rib forms 52 FRP shear grid between frame and facade Steel reinforcing of structural frame

53 Full-scale experimental validation DC-7 Line C B3 DC-10 Line B B4 53 Full-scale testing under reversed cyclic uniform pressure loading representing extreme high-wind loads

54 Inward pressure (suction) Outward pressure 54

55 Closing Remarks 55 Innovative use of FRP with careful analysis techniques will lead to significant advancements in design, construction and sustainability of precast concrete structures and bridges. Questions?