A Study of Anchored Fiber Reinforced Plastics Sheet PileYeou-Fong Li

1 and Ching-Kai Chen2

Keywords ： Glass Fiber Reinforced Plastic Composite Material, Frame, Grating, Pushover Test

Introduction: FRP (Fiber Reinforced Plastics) composite materials have the merits of light weight, high strength, well-durability and other characteristics. In this study, FRP sheet piles were used to solve the corrosion problem of the geotechnical structures.

1Professor of the Department of Civil Engineering , NTUT, Taipei, Taiwan .

2Master of the Department of Civil Engineering, NTUT, Taipei, Taiwan.

3 Points Bending moment Experiment

Ansys Analysis Result

Span depth ratio 18 14 10 8

Experience(mm) 18.12 9.59 4.86 2.84

Euler’s beam(mm) 18.54 8.66 3.16 1.64

Error 2.32% 9.70% 34.98% 42.25%

Timoshenko’s beam(mm)

21.59 11.03 4.66 2.99

Error 19.15% 15.02% 4.12% 5.28%

跨深比 18 14 10 8

跨度 (m) 3.66 2.84 2.03 1.63

ANSYS(mm) 18.28 9.49 4.45 2.70

實驗值 (mm) 18.12 9.59 4.86 2.84

ANSYS與實驗相對誤差 0.16% 0.10% 8.44% 4.93%

Angle 45° 60° 90°

Stiffness (kN/mm) 0.957 1.104 1.115

Cross section area(cm2) 93.86 95.94 105.868

Stiffness/Cross section area (kN/mm·cm2)

0.01020 0.011507 0.01053

Moment of inertia(cm4) 6,496 7,082 8,954

Stiffness/Moment of inertia (kN/mm·cm4)

0.000161 0.000156 0.000125

First, the 3-point bending experiment was performed, and changing the span depth ration to obtain the specimen’s stiffness. The specimen of 18-span depth ratio whose displacement is more approach to Euler’s Beam theory from the experimental observation.

Using the result of the experiment to feedback the finite element analysis model, and then we found the error of numerical model’s result is less about 8.5 %.

Then changing the numerical model’s angle and thickness to investigate the stiffness and stiffness over cross section area. According to the numerical FRP sheet pile model, the 60°-angle FRP sheet pile is most economical between 45°, 60° and 90°. Furthermore, the thickness of the 19.05 mm FRP sheet pile is more economical than the thickness of the 6.35 mm and 12.70 mm FRP sheet piles.

版樁厚度 6.35 12.70 19.05

Stiffness(kN/mm) 1.10 2.24 3.17

Stiffness/Cross section area (kN/mm·cm2)

0.011507 0.013272 0.013953

Stiffness/Moment of inertia (kN/mm·cm4)

0.000186 0.000192 0.000196

18-span depth ratio 14-span depth ratio

10-span depth ratio 8-span depth ratio

Plaxis Analysis Result Then, three kinds of sheet piles (FRP, PVC and steel) were modeled using Plaxis. We found that the PVC sheet pile has the lowest stiffness which causes its deflection concerns and a very low safety factor. On the other hand, the steel sheet pile enjoys the highest stiffness, lowest deflection and consequently, the largest safety factor. Furthermore, in order to improve the safety of the slope of the embankment, this study compares results of the the cantilever with the anchored FRP sheet pile. According to the results, the safety factor of the anchored FRP sheet pile is higher than cantilever one by 1.9 folds.

打設深度 1 m 2 m 3 m懸臂式安全係數 1.74 2.56 3.10錨碇式安全係數 4.56 4.82 5.07提升之安全係數 2.82 2.26 1.97

版樁材料 FRP版樁 PVC版樁 鋼板樁極限強度 460.38 MPa 54.92 MPa 390.00 MPa

打樁深度最大彎矩

安全係數

最大彎矩

安全係數

最大彎矩

安全係數

1 m4.72M

Pa 97.6

4.70

MPa 11.7

5.44M

Pa 71.7

2 m 5.97 77.2 3.16 17.4 9.22 42.3

3 m 5.77 79.8 4.26 12.9 11.08 352

A Study of Anchored Fiber Reinforced Plastics Sheet PileYeou-Fong Li

1 and Ching-Kai Chen2

Keywords ： Glass Fiber Reinforced Plastic Composite Material, Frame, Grating, Pushover Test

Introduction: FRP (Fiber Reinforced Plastics) composite materials have the merits of light weight, high strength, well-durability and other characteristics. In this study, FRP sheet piles were used to solve the corrosion problem of the geotechnical structures.

1Professor of the Department of Civil Engineering , NTUT, Taipei, Taiwan .

2Master of the Department of Civil Engineering, NTUT, Taipei, Taiwan.

3 Points Bending moment Experiment

Ansys Analysis Result

Span depth ratio 18 14 10 8

Experience(mm) 18.12 9.59 4.86 2.84

Euler’s beam(mm) 18.54 8.66 3.16 1.64

Error 2.32% 9.70% 34.98% 42.25%

Timoshenko’s beam(mm)

21.59 11.03 4.66 2.99

Error 19.15% 15.02% 4.12% 5.28%

跨深比 18 14 10 8

跨度 (m) 3.66 2.84 2.03 1.63

ANSYS(mm) 18.28 9.49 4.45 2.70

實驗值 (mm) 18.12 9.59 4.86 2.84

ANSYS與實驗相對誤差 0.16% 0.10% 8.44% 4.93%

Angle 45° 60° 90°

Stiffness (kN/mm) 0.957 1.104 1.115

Cross section area(cm2) 93.86 95.94 105.868

Stiffness/Cross section area (kN/mm·cm2)

0.01020 0.011507 0.01053

Moment of inertia(cm4) 6,496 7,082 8,954

Stiffness/Moment of inertia (kN/mm·cm4)

0.000161 0.000156 0.000125

First, the 3-point bending experiment was performed, and changing the span depth ration to obtain the specimen’s stiffness. The specimen of 18-span depth ratio whose displacement is more approach to Euler’s Beam theory from the experimental observation.

Using the result of the experiment to feedback the finite element analysis model, and then we found the error of numerical model’s result is less about 8.5 %.

Then changing the numerical model’s angle and thickness to investigate the stiffness and stiffness over cross section area. According to the numerical FRP sheet pile model, the 60°-angle FRP sheet pile is most economical between 45°, 60° and 90°. Furthermore, the thickness of the 19.05 mm FRP sheet pile is more economical than the thickness of the 6.35 mm and 12.70 mm FRP sheet piles.

版樁厚度 6.35 12.70 19.05

Stiffness(kN/mm) 1.10 2.24 3.17

Stiffness/Cross section area (kN/mm·cm2)

0.011507 0.013272 0.013953

Stiffness/Moment of inertia (kN/mm·cm4)

0.000186 0.000192 0.000196

18-span depth ratio 14-span depth ratio

10-span depth ratio 8-span depth ratio

Plaxis Analysis Result

Then, three kinds of sheet piles (FRP, PVC and steel) were modeled using Plaxis. We found that the PVC sheet pile has the lowest stiffness which causes its deflection concerns and a very low safety factor. On the other hand, the steel sheet pile enjoys the highest stiffness, lowest deflection and consequently, the largest safety factor. Furthermore, in order to improve the safety of the slope of the embankment, this study compares results of the the cantilever with the anchored FRP sheet pile. According to the results, the safety factor of the anchored FRP sheet pile is higher than cantilever one by 1.9 folds.

Depth 1 m 2 m 3 m

Safty Factor of Cantilever Sheet pile 1.74 2.56 3.10Safty Factor of Anchored sheet pile

4.56 4.82 5.07Increment of Safety Factor 2.82 2.26 1.97

FRP Cantilever sheet pile

FRP Anchored sheet pile

Material

DepthFRP PVC Steel

1 m 1.71 1.54 1.71

2 m 2.07 1.75 2.60

3 m 2.56 1.83 3.69