Author Contributions
Conceptualization, P.K.; data curation, M.A. and K.K.; formal analysis, M.A. and K.K.; funding acquisition, P.K.; investigation, M.A. and K.K.; methodology, M.A. and K.K.; project administration, M.A. and K.K.; resources, M.A., P.K. and K.K.; supervision, P.K.; visualization, M.A. and K.K.; writing—original draft, M.A., P.K. and K.K.; writing—review and editing, M.A., P.K. and K.K. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Test element for measuring the mechanical properties of a composite during compression: empty tube with winding angle of 20° on a test stand.
Figure 1.
Test element for measuring the mechanical properties of a composite during compression: empty tube with winding angle of 20° on a test stand.
Figure 2.
View of a pair of strain gauges at point 1—strain gauges in the picture covered with adhesive to protect against mechanical damage and moisture.
Figure 2.
View of a pair of strain gauges at point 1—strain gauges in the picture covered with adhesive to protect against mechanical damage and moisture.
Figure 3.
Pipe rims for wall thickness measurements.
Figure 3.
Pipe rims for wall thickness measurements.
Figure 4.
Measurement of fiber winding angle for pipe with declared winding angle 20°.
Figure 4.
Measurement of fiber winding angle for pipe with declared winding angle 20°.
Figure 5.
Test samples made of 40-cm-long hollow tube. View after destruction of elements with a fiber winding angle of: (a) 20°, (b) 55° and (c) 85°. Concrete plug visible in the last sample.
Figure 5.
Test samples made of 40-cm-long hollow tube. View after destruction of elements with a fiber winding angle of: (a) 20°, (b) 55° and (c) 85°. Concrete plug visible in the last sample.
Figure 6.
Arrangement of strain gauges to be applied to pipe: v—vertical, h—horizontal.
Figure 6.
Arrangement of strain gauges to be applied to pipe: v—vertical, h—horizontal.
Figure 7.
Stress-strain relationship for test elements made of 40-cm-long hollow composite tube.
Figure 7.
Stress-strain relationship for test elements made of 40-cm-long hollow composite tube.
Figure 8.
Samples cut from pipes with winding angles of glass fibers θ = 85° (highest), θ = 55° (middle) and θ = 20° (lowest) to test the peripheral tensile strength and modulus of elasticity.
Figure 8.
Samples cut from pipes with winding angles of glass fibers θ = 85° (highest), θ = 55° (middle) and θ = 20° (lowest) to test the peripheral tensile strength and modulus of elasticity.
Figure 9.
Ring sample of pipe with winding angle θ = 85° on the test stand after completion of experiment.
Figure 9.
Ring sample of pipe with winding angle θ = 85° on the test stand after completion of experiment.
Figure 10.
Tensile σ-ε relationships in circumferential direction, obtained for fiber reinforced polymer (FRP) ring samples of pipe with winding angle θ = 55°.
Figure 10.
Tensile σ-ε relationships in circumferential direction, obtained for fiber reinforced polymer (FRP) ring samples of pipe with winding angle θ = 55°.
Figure 11.
Idea of determining modulus of elasticity at circumferential tension, presented for FRP ring samples of pipe with winding angle θ = 55°.
Figure 11.
Idea of determining modulus of elasticity at circumferential tension, presented for FRP ring samples of pipe with winding angle θ = 55°.
Figure 12.
Force-displacement relationship for test specimens made from a 40-cm-long composite pipe filled with concrete.
Figure 12.
Force-displacement relationship for test specimens made from a 40-cm-long composite pipe filled with concrete.
Figure 13.
Relation compressive force vs average deformation in short CFFT columns with different fiber winding angles.
Figure 13.
Relation compressive force vs average deformation in short CFFT columns with different fiber winding angles.
Figure 14.
View after failure of 200-cm-long CFFT test specimens with fiber winding: (a) 20°, (b) 55° and (c) 85°.
Figure 14.
View after failure of 200-cm-long CFFT test specimens with fiber winding: (a) 20°, (b) 55° and (c) 85°.
Figure 15.
Force-displacement relation for test specimens made of 200-cm-long composite pipe filled with concrete.
Figure 15.
Force-displacement relation for test specimens made of 200-cm-long composite pipe filled with concrete.
Figure 16.
The development of average deformations in the long CFFT columns with different fiber winding angles.
Figure 16.
The development of average deformations in the long CFFT columns with different fiber winding angles.
Figure 17.
Testing of rheological deformations (creep and shrinkage).
Figure 17.
Testing of rheological deformations (creep and shrinkage).
Figure 18.
Creep curves at axial compression (t0 = 63 d) at stress σ = 0.46·fc(28).
Figure 18.
Creep curves at axial compression (t0 = 63 d) at stress σ = 0.46·fc(28).
Table 1.
Summary of the tested elements and their selected features.
Table 1.
Summary of the tested elements and their selected features.
No. | Element Designation | Height [m] | Angle of Cross Winding of Fibers |
---|
1 | S-85 | 0.4 | 85° |
2 | S-55 | 0.4 | 55° |
3 | S-20 | 0.4 | 20° |
4 | L-85 | 2.0 | 85° |
5 | L-55 | 2.0 | 55° |
6 | L-20 | 2.0 | 20° |
Table 2.
Compressive strength of the composite in axial compression depending on the angle of glass fiber winding.
Table 2.
Compressive strength of the composite in axial compression depending on the angle of glass fiber winding.
No. | Fiber Winding Angle | Average Pipe Wall Thickness [mm] | Tube Cross-Sectional Area [mm2] | Destructive Force [kN] | Compressive Strength [MPa] |
---|
1 | 20° | 7.1 | 4610.3 | 656.5 | 142.4 |
2 | 55° | 6.5 | 4229.4 | 332.6 | 78.6 |
3 | 85° | 5.8 | 3729.9 | 324.4 | 87.0 |
Table 3.
Computed results of longitudinal elasticity modulus and ultimate shortening of tested pipe composite during compression.
Table 3.
Computed results of longitudinal elasticity modulus and ultimate shortening of tested pipe composite during compression.
No. | Fiber Winding Angle | Elasticity Modulus | Ultimate Longitudinal Shortening |
---|
EFRP,c [GPa] | εFRP,u,c [‰] |
---|
1 | 20° | 36.26 | 3.86 |
2 | 55° | 14.71 | 7.20 |
3 | 85° | 14.13 | 6.67 |
Table 4.
Medium values of mechanical parameters of pipe composite at circumferential tension stress.
Table 4.
Medium values of mechanical parameters of pipe composite at circumferential tension stress.
Fiber Winding Angle | Modulus of Elasticity | Circumferential Stress | Ultimate Circumferential Strain |
---|
EFRP,circ | fFRP,circ | εFRP,u,circ |
---|
[GPa] | [MPa] | [‰] |
---|
20° | 6.02 | 46.1 | 7.66 |
55° | 20.63 | 301.3 | 14.6 |
85° | 46.38 | 692.2 | 14.93 |
Table 5.
Failure forces obtained for short concrete-filled FRP tubes (CFFT) columns depending on the angle of glass fiber winding of the composite pipe.
Table 5.
Failure forces obtained for short concrete-filled FRP tubes (CFFT) columns depending on the angle of glass fiber winding of the composite pipe.
No. | Fiber Winding Angle | Failure Force [kN] |
---|
1 | 20° | 1608.7 |
2 | 55° | 2144.5 |
3 | 85° | 4136.7 |
Table 6.
Failure forces obtained for long CFFT columns depending on the angle of glass fiber winding of the composite pipe.
Table 6.
Failure forces obtained for long CFFT columns depending on the angle of glass fiber winding of the composite pipe.
No | Glass Fiber Winding Angle | Failure Force [kN] |
---|
1 | 20° | 1600.0 |
2 | 55° | 1406.3 |
3 | 85° | 1863.7 |