Thin-Wall Synthetic Fiber Reinforced Concrete Pipe Performance under Cyclic Loading

This paper evaluated mixed mode I/II fracture toughness of fiber-reinforced concrete using cracked semi-circular bend (SCB) specimens subjected to three-point bending test. Additionally, a comparison was made between the experimental results and the estimations made by different theoretical criteria. Natural and synthetic fibers at various concentrations were used in this study. After producing cracks in SCB specimens at different inclination angles to induce different mixed mode loading conditions (from pure mode I to II), the fracture toughness of SCB specimens was determined. Furthermore, the compressive, splitting tensile, and flexural strength of natural and synthetic fiber-reinforced concrete were measured after 7 and 28 days of curing. While there is an increase in the aforementioned strengths with fiber content increase, 0.3% was found to be the optimum percentage regarding fracture toughness for both fibers. Also, the comparison between the experimental and theoretical results showed that generalized maximum tangential stress criterion estimated the experimental data satisfactorily.

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Investigating the Effects of Fiber Reinforced Concrete on the Performance of End-Zone of Pre-Stressed Beams

Materials ◽

10.3390/ma12132093 ◽

2019 ◽

Vol 12 (13) ◽

pp. 2093

Author(s):

Jalal ◽

Shafiq ◽

Zahid

Keyword(s):

Reinforced Concrete ◽

Cyclic Loading ◽

Polyvinyl Alcohol ◽

Strain Energy ◽

Fiber Reinforced Concrete ◽

Coated Steel ◽

Fiber Reinforced ◽

Cracking Behavior ◽

Industrial Buildings ◽

Post Tensioned

This paper presents the results of the behavior of end zone of post-tensioned (PT) beams made of fiber reinforced concrete (FRC). The principal aim of using FRC was to enhance the ductility and post-cracking behavior of end-zone of post-tensioned beams. A stronger and tougher end-zone of PT-beams is necessary when it is subjected to dynamic loading. Post-tensioned (PT) beams are typically used for the construction of bridges and industrial buildings, which are often subjected to vibrations and cyclic loading. Pre-mature cracking of the end zone (EZ) of a PT-beam is considered the type of problem that may cause the structural collapse. In this research program, polyvinyl alcohol (PVA) and copper-coated steel (CCS) fibers were used in concrete for improving the EZ performance of PT-beams. The use of FRC caused a 50% reduction in the shear reinforcement within the end zone of the PT-beam, which also avoided the congestion of steel in the end zone. Hence, the concrete was placed homogeneously, and smooth finished surfaces of the beams were obtained. FRC controlled the bursting of the end zone during the transfer of the full pre-stress force, and approximately 25% increment in the strain energy of the end zone was observed, which was also found efficient in strain diminution along the length of the beam.

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A new test method for evaluating the long-term performance of fiber-reinforced concrete pipes

Advances in Structural Engineering ◽

10.1177/1369433219894243 ◽

2019 ◽

Vol 23 (7) ◽

pp. 1336-1349 ◽

Cited By ~ 1

Author(s):

Fouad T Al Rikabi ◽

Shad M Sargand ◽

Issam Khoury ◽

John Kurdziel

Keyword(s):

Finite Element ◽

Reinforced Concrete ◽

Steel Reinforcement ◽

Fiber Reinforced Concrete ◽

Synthetic Fiber ◽

Concrete Pipes ◽

Concrete Pipe ◽

Long Term Performance ◽

Term Performance

Synthetic fibers have been used recently to minimize the need for steel reinforcement in the concrete pipe to enhance their ductility. However, synthetic fiber has properties that may change over time due to its viscoelastic behavior. The objective of this study is to investigate the long-term performance of fiber-reinforced concrete pipes using a new test frame. A three-dimensional finite element model was created for the long-term testing frame to ensure its compliance with the American Society for Testing and Materials requirement. The finite element results showed that the testing frame successfully transferred the load to the concrete as the pipe cracked at the location where high flexural stresses are expected. Concrete pipe reinforced with synthetic fiber dosage of 9 kg/m3 along the steel reinforcement area of 5.7 cm2/m was tested to evaluate the concrete pipe system performance. The pipe was tested under two load stages for 120 days each. Load stages 1 and 2 included applying 40% and 70% of the ultimate load obtained by the authors in a previous study, respectively. The strain and deflection increased linearly within 5 days of applying the load and then leveled off. The pipe showed a slight increase in the crack width and deflection, indicating that fiber creep did not have a significant impact on the long-term performance of the concrete pipe. Also, it was observed that strain values surpassed those for plain concrete material, suggesting that including synthetic fiber in the concrete pipe mix enhanced the pipe ductility.

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