Glass Fiber Reinforced Plastic Tube Research Articles

Study on the effect of multi-factor compound action on long-term tensile performance of GFRP composite pipe and life prediction analysis

In this work, the glass fiber reinforced plastic (GFRP) composite pipes used as sewerage pipes in oil and gas field environments were studied. The accelerated aging experiments were carried out under the simulated environments of three typical oil field media which including circulating air, simulated produced water and standard simulated oil. Scanning electron microscopy (SEM) was adopted to observe the microscopic morphology of the aged GFRP tubes under the three conditions. The microstructural characteristics of the aged tubes and the evolution process of internal defects were also analyzed and evaluated in combination with micro-CT technology. The attenuation pattern of the hoop tensile strength of the aged pipes was measured via the separation disk method, and the service life prediction was carried out based on the Arrhenius theory with the hoop strength as the life index. The results show that the accumulation of aging time and continuous heat input will aggravate the expansion of internal pores and cause the aggregation of small-volume defects into large-volume defects. Especially in the simulated oil environment, which has the highest sensitivity to defects. The maximum porosity reaching 1.5 % and the maximum volume of individual defects exceeding 106 μm3 after aging for 4000 h at 95 °C. The thermal aging process under the three environmental conditions had similar aging characteristics, and interfacial damage of the glass fibers was observed in all of them. The variability of hydrothermal aging is related to the hydrolytic behavior of the glass fibers, which is associated with the progressive dissolution damage of the SiO2 network in the glass fibers, as well as the breaking of silane bonds. Thus, the hydrothermal environment had the most significant effect on the hoop tensile strength decay. Ultimately, 75 % strength retention was taken as the end-of-life indicator. The predicted service life based on the Arrhenius model for the three environments of thermo-oxygen, hydrothermal and simulated oil were 23.5, 23.1 and 28.5 years at 20 °C, and 12.2, 4.9 and 10.3 years at 40 °C, respectively.

Experimental Study and Numerical Analysis of the Seismic Performance of Glass-Fiber Reinforced Plastic Tube Ultra-High Performance Concrete Composite Columns.

To investigate the impact of the filament winding angle of glass-fiber reinforced plastic (GFRP) on the seismic behavior of GFRP tube ultra-high performance concrete (UHPC) composite columns, this study designs two types of GFRP tube UHPC composite columns. Quasi-static tests are conducted on the specimens subjected to horizontal reciprocating load and axial force, and the skeleton curve characteristics of the structure are analyzed. Furthermore, a finite element analysis model of the composite column is established to explore the effects of the diameter-thickness ratio, circumferential elastic modulus of confined tubes, and tensile strength of concrete on the seismic performance of the composite column. The analysis includes a review of the skeleton curve, energy dissipation capacity, and stiffness degradation of the structure under different designs. The results indicate that the use of GFRP tubes effectively enhances the seismic performance of UHPC columns. The failure mode, peak load, and peak displacement of the composite columns are improved. The finite element analysis results are in good agreement with the experimental results, validating the effectiveness of the analysis model. Extended analysis reveals that the bearing capacity of the specimen increases while the energy dissipation capacity decreases with a decrease in the diameter-thickness ratio and an increase in the circumferential elastic modulus. Although the tensile strength of concrete has some influence on the seismic performance of the specimen, its effect is relatively small. Through regression analysis, a formula for shear capacity suitable for GFRP tube UHPC composite columns is proposed. This formula provides a theoretical reference for the design and engineering practice of GFRP tube UHPC composite columns.

Axial compressive behavior of self-compacting micro-expansive high-strength concrete confined by glass fiber reinforced plastic tube

To solve the instability of the compression bars in the space truss composed of GFRP tubes, a composite column with high-strength concrete (HSC) confined by glass fiber-reinforced plastic (GFRP) tube was proposed. High-strength self-compacting micro-expansive concrete with a slump greater than 255 mm was produced under normal-temperature curing conditions and confined by GFRP tubes. A mechanical performance test of the GFRP-confined HSC short column under axial compression was performed. The effects of GFRP tube types, concrete expansion agent, constraint effect, ultimate load capacity, and failure mode of the composite structure were discussed and analyzed through the test. A model of the stress-strain response of the GFRP confined HSC column was proposed. The results show that the 45° fiber-wound GFRP tube has a significant restraining effect on the HSC. The stress-strain relationship increases quadratically in a linear fashion. When the composite column was damaged, the GFRP fiber was broken and the concrete was crushed. The ultimate strength was about 1.5 times that of unconstrained HSC columns, and the loading method has less influence on the results. The expansion agent has a significant effect on the deformation performance of the composite column, and its ultimate strain was about 1.4 times that of the composite column without expansion agent.

Axial compressive behavior of GFRP tube confined seawater coral aggregate concrete reinforced with epoxy-coated bars

An experimental study on the mechanical behavior of glass fiber reinforced plastic (GFRP) tube confined seawater coral aggregate concrete reinforced with epoxy-coated steel bars (GSCACESB) under axial compression were systematically performed. Three different parameters were considered: concrete type (seawater coral aggregate concrete and ordinary concrete), GFRP tube thickness (4 mm, 5 mm and 6 mm) and reinforcement ratio (longitudinal and circumferential reinforcement ratios). Typical influences of concrete, GFRP tube and reinforcement on the bearing capacity, deformation and load-deformation curve of GSCACESB were investigated. Test results showed that the failure pattern of GSCACESB was similar to that of GFRP tube confined ordinary concrete (GCOC). However, the bearing capacity of GSCACESB was significantly decreased compared to GCOC due to the less confinement between seawater coral aggregate concrete and outer tube. The peak deformation and bearing capacity of GSCACESB increased with the increases of tube thickness, and longitudinal and circumferential reinforcement ratios. The load-deformation curve of GSCACESB was divided into elastic-plastic and hardening stages. The more the reinforcement ratio, the less the curve curvature. An analytical expression considering the influences of SCAC was also proposed, which could predict the structural response of GSCACESB. Finally, the numerical simulation analysis was undertaken to investigate the GSCACESB mechanical behaviors.

Crashworthiness of circular fiber reinforced plastic tubes filled with composite skeletons/aluminum foam under drop-weight impact loading

Carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP) have shown great promise in the design of light-weight thin-walled energy absorbers. Herein, circular CFRP/GFRP hybrid tubes and tubes, reinforced with internal composite skeletons (XS and OS), were fabricated to further enhance the energy absorption capacities. The crashworthiness and failure pattern of reinforced structures were compared with the hollow and aluminum foam-filled composite tubes. Moreover, low-velocity drop-weight impact tests were carried out to investigate the effect of hybridization design and filler types on the energy dissipation mechanism under axial compression. The experimental results revealed that the hollow composite tubes collapsed in progressive and the impact energy was absorbed by the generation of cracks, fiber fracture and friction. Also, the GFRP tubes exhibited better crashworthiness than CFRP tubes under low velocity impact, which was different from the quasi-static compression conditions. In contrast to hollow counterparts, the mean crushing force (MCF) of foam-filled tubes was improved by approximately 40%, whereas the specific energy absorption (SEA) was reduced by 30% due to the low weight efficiency of the aluminum foam. The filling of XS-skeleton divided the tube into four cells and improved the MCF by more than 10%. However, it reduced the SEA by around 8% due to unstable and inefficient deformation of XS-skeleton during crushing. By contrast, the OS-skeleton divided the hollow tube into more cells and collapsed progressively, resulting in superior energy absorption characteristics. Herein, the OS-filled GFRP tube was found to be the most crashworthy structure that improved the crushing force efficiency (CFE) and SEA by 50% and 7%, respectively.

Compressive behavior of concrete-filled GFRP tubular stub columns after being subjected to freeze-thaw cycles

This paper aims to investigate the mechanical properties of concrete-filled glass fiber reinforced plastic (GFRP) tubular stub columns after being subjected to freeze-thaw cycles (FTCs). A total of 72 concrete-filled GFRP tubular (CFGT) stub columns treated with different FTCs were tested under axial load. The ultimate capacity, initial stiffness, load-displacement curves, load-strain curves, and failure modes were obtained and analyzed. Test results indicated that the failure phenomena of the specimens under axial compression were similar, mainly including the fracturing of GFRP tube and crushing of core concrete. The FTCs, concrete strength and column height all had a significant influence on the failure modes of the specimens. The ultimate capacity and initial stiffness decreased evidently with the increase of the number of FTCs. By increasing the height of the column, the ultimate capacity and deformation capacity of square column after FTCs could be effectively improved. The change of ultimate capacity of the CFGT column after FTCs was the result of the combined effect of FTCs, concrete compressive strength and column height. Finally, the simplified formulas for calculating the ultimate capacity of CFGT stub columns after FTCs were proposed.

Research on I steel reinforced concrete-filled GFRP tubular short columns

This paper presents an experimental investigation on I steel reinforced concrete-filled glass fiber reinforced plastic (GFRP) tubular short columns under axial load. The study aimed to explore the effect of three parameters of steel ratio, thickness of GFRP tube and concrete strength on the mechanical behavior of I steel reinforced concrete-filled GFRP tubular short columns under axial load. A total of twenty-seven I steel reinforced concrete-filled GFRP tubular short column specimens were tested with steel ratio of 4.6%, 6.8% and 8.3%, thicknesses of GFRP tube of 5, 8 and 10mm and concrete strengths from 20 to 40MPa. What's more, three reference tests including the pure I-section, pure GFRP tube and fully filled GFRP tube without I-sections were conducted in this paper to compare with the proposed composite sections. The failure modes, axial load-strain relationships, axial load-axial displacement relationships and ultimate loads are presented in this paper. The strength index is proposed to better evaluate the section behavior of the composite columns. Experimental results show that the failure modes of all the specimens are basically the same. The transverse strain of GFRP tube is smaller than the axial strain under the same axial load in the linear stage. Specimens with higher concrete strength obtain higher load-bearing capacity but lower deformation capacity and strength index. Increasing steel ratio fails to improve the load-bearing capacity and stiffness, but can lighten the weight of the columns. The results also indicate that thicker GFRP tube can both improve the load-bearing capacity and obtain better deformation capacity but generate a problem of low cost-efficient. Design formulas for the load-bearing capacity of I steel reinforced concrete-filled GFRP tubular short columns under axial load are proposed.

Axial crush behavior and energy absorption capability of foam-filled GFRP tubes under elevated and high temperatures

Foam-filled circular composite tube has been widely used in safety design of automobile, space craft recovery and so on due to its advantage of high energy absorption, light weight and anti-corrosion. But the axial crush behavior and energy absorption capability of foam-filled composite tubes are threatened by elevated and high temperatures. In practice, the effects of high temperatures cannot be ignored because composites and foam are sensitive to temperature. In this paper, an experimental investigation was carried out to evaluate the effectiveness of energy absorption of foam-filled circular glass fiber reinforced plastic (GFRP) tube under elevated and high temperatures. The temperature range was from 20°C to 110°C, covered the glass transition temperature (92°C). In the meantime, the effects of high environmental temperatures on failure mode, crush force efficiency, energy ductility coefficient and specific energy absorption were also studied. The test results demonstrated that the axial crush behavior and energy absorption capacity of foam-filled GFRP tubes were determined by the environmental temperature. The foam-filled GFRP tubes can achieve top crashworthiness performance when the environmental temperature was less than 70°C.

GFRP-tube confined RAC under axial and eccentric loading with and without expansive agent

This paper presents the results of axial compression tests on recycled aggregate concrete (RAC) confined by glass fiber reinforced plastic (GFRP) tubes. The objective of this study is to evaluate the mechanical properties of GFRP-tube confined RAC under axial and eccentric compressive loading. The main parameters in the experiment are recycled coarse aggregate (RCA) replacement percentages (0%, 30%, 50%, 70% and 100%) and expansive agent contents (0%, 8% and 15%). Sixteen specimens were prepared, six specimens were tested under axial concentric compression load and ten specimens were tested under eccentric compression loading. Research findings indicate that both the RAC strength and deformation are obviously improved with the additions of expansive agent. It is also found that the peak stress of RAC confined by GFRP tubes decreases while the corresponding strain increases when the RCA replacement percentage is increased.

Seismic Behavior of Recycled Aggregate Concrete Filled Steel and Glass Fiber Reinforced Plastic Tube Columns

This paper presents the results of seismic tests on the recycled aggregate concrete filled steel tube (RCFS) and recycled aggregate concrete filled glass fiber reinforced plastic (GFRP) tube (RCFF) columns. The objective of this study is to evaluate the seismic behavior of steel/ GFRP tube in-filled recycled aggregate concrete (RAC) columns. The main parameters in the tests are the recycled coarse aggregate (RCA) replacement percentage and the tube material. The results show that both deformation and bearing capacities of RCFF and RCFS columns are greatly improved. The seismic behavior of RCFS columns is better than that of RCFF columns. Research findings also indicate that the energy dissipation capacity and the ductility slightly change with the variation of recycled coarse aggregate replacement percentage, whereas the bond-slip has little effect on the seismic behavior. Besides the experiments, a finite element method (FEM) analysis is also conducted. It is found that the seismic behavior of both RCFS and RCFF columns is decreased with the increase of the axial load ratio.

Effect of non-penetrating impact damages of pre-stressed GRP tubes at low velocities on the burst strength

In this study, failure behavior of pre-stressed Glass Fiber Reinforced Plastic (GRP) tubes subjected to low velocity impact was investigated. Filament wound E-glass/epoxy composite tubes with a winding angle of ±55° were used in the experiments. The tubes pre-stressed to 32bars internal pressure, one of the specified operating pressures according to ANSI/AWWA C950 standards. Both prestressed and non-prestressed GRP tubes were subjected to low velocity impact tests at 5, 10 and 15J low energy levels. Plots of contact force and internal pressure with respect to time and those of force–displacement were obtained and damages occurred on the specimens were examined by means of reflected and transmitted light photography and light microscope. No marked fiber breakages are observed; however, debonding and some sort of delamination on the layers were observed. The GRP tubes with impact damages were subjected to monotonic burst pressures up to failure based on the ASTM D 1599-99 standards. Burst damages on the tubes were studied and variations of their corresponding burst strengths were spotted. Besides that, diameter changes with internal pressures were determined during the tests. Diameter changes with internal pressures for the impacted and the non-impacted tubes were found to be the same.

Mechanical properties of confined recycled aggregate concrete under axial compression

This paper presents the results of axial compression tests on recycled aggregate concrete (RAC) confined by steel tubes and RAC confined by glass fiber reinforced plastic (GFRP) tubes. The objective of this study is to evaluate the mechanical properties of confined RAC under axial compressive loading. The main parameters in the tests are the recycled coarse aggregate replacement percentage and the tube material. Research findings indicate that both the strength and deformation of RAC are obviously improved. The mechanical properties of RAC confined by steel tubes are better than those of RAC confined by GFRP tubes when all parameters are kept the same. It is also found that the peak stress of RAC confined by steel tubes decreases while the corresponding strain increases when the replacement percentage of RCA is increased, which are similar to those of RAC confined by GFRP tubes. Expressions for the peak stress and the stress–strain relationship of the confined RAC are then obtained based on the test data. Finally, the finite element method (FEM) is applied to study the effect of the outer tube thickness and the core RAC strength on the stress–strain relationship of confined RAC.

Strength design of the adhesive joint connecting a carbon steel shaft to a GFRP tube (1st report, A case of combined tensile and torsional loads)

The strength of joints between a carbon steel shaft and a glass fiber reinforced plastic (GFRP) tube connected with adhesive resin was investigated analytically and experimentally. The stress distributions under the combined tensile and torsional loads were calculated using the finite element method. It was shown that stress concentrations occurred at the edges of the overlap between two shafts. The strains measured by the strain gauges on the surface of the shaft joints were in close agreement with the calculated results. The strength of the adhesive shaft joint was predicted by applying the strength laws of GFRP, carbon steel, the adhesive layer and their interfaces to the calculated stress distributions. The predicted strength of the adhesive shaft joint under the combined loads was in good agreement with the experimental results of the initial cracking load.