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In this paper, further analysis from the result of spun pile test under reverse flexural load and combined with two levels constant axial load, 40 tons (0.08fc'Ag) and 80 tons (0.16fc'Ag) is presented. The analysis is related to the confinement behavior of the concrete section of pile using the low amount of spiral reinforcement. It was shown that the strain readings from the spiral reinforcement indicate a subtle contribution regarding the confinement mechanism of the hollow section of a pile. In addition, it was evident that spiral reinforcement seems to be compressed when the concrete section resists compression strain due to flexural load. The crushing of concrete at ultimate condition could also not be resisted by spiral reinforcement by any means.

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This paper presents an experimental study of the behavior of Normal Concrete Beams (NCB) and composite beams with lightweight foamed concrete (CB), reinforced with steel bar measuring 2 f 8 mm in the compressive section and 2 D 16 mm in the tensile section, shear steel bar f 8 mm. The sample consisted of two normal concrete beams (NCB) and two composite beams with lightweight foamed concrete (CB). The main variables in this study are the type of concrete, the type of steel bar and the flexural behavior. The beam samples were tested by two-point loading, failure mode and crack width were observed. The results showed that the flexural process of normal concrete blocks (NCB) and composite beams with lightweight foamed concrete (CB) was almost the same. There is no slip failure at the combined interface, the flexural capacity of the composite beam with lightweight foamed concrete can be calculated based on the statics analysis and plane-section assumptions. To calculate the ultimate capacity of a composite beam with lightweight foamed concrete is to convert a section consisting of more than one fc' to an equivalent section consisting of one fc'. Furthermore, it is validated by calculating the theoretical moment capacity and comparing the theoretical moment capacity of the experimental results. The results of the flexural test, composite beam with lightweight foamed concrete (CB) showed ductile deflection behavior, diagonal crack patterns, and low flexural capacity of the beam (NCB). Doi: 10.28991/cej-2021-03091673 Full Text: PDF

Abstract-Structures built in aggressive environments such as in the sea/marine environment need to be carefully designed, due to possibility of chloride ion penetration into the concrete. One way to reduce the strength degradation in such environment is to use FRP, which is attached to the surface of R/C using epoxy. The study presented is focused on determining the effect of the sea water to the capacity of GFRP as flexural reinforcement elements. Beams of 10×10×40 cm dimension were designed without reinforcing bars. The samples were tested using variation to the distance to the sea and duration of the contact to the sea.The result showed that the use GFRP increased the flexural strength 84,21%, compared to the normal beam, without GFRP. It can also be seen that the closer the distance to the sea, the higher the strength degradation of the beam. The sample rinsed in the water has strength 2.13 kN after 9 months, while sample put at a distance 1 km from the seam has strength 2.53 kN. The result of this study also showed that for areas closer to the sea has a greater effect in terms decreasing flexural capacity of the beam IndexTerms-Flexural strength, GFRP, marine environment.

This research investigates the effect of the presence of infilling concrete inside of the middle void of the spun pile on its flexural behavior. The flexural monotonic load without axial load testing was conducted on the full-scale of two spun piles with infilling concrete. The dimensions of the pile were 400 mm in diameter, 75 mm in wall thickness, and 6,000 mm in length. The compressive strength of the concrete of the spun pile and infilling concrete was 58.4 MPa and 26.9 MPa, respectively. The observed flexural behaviors were the moment capacity, displacement ductility factor, and failure modes. Comparing with the previous research result about the testing of the spun pile without infilling concrete, the present testing results show that the presence of infilling concrete as the core of the spun pile’s section did not have a significant effect on the flexural performances of tested spun pile. Low compressive stress on compression fiber, due to no axial load, caused no concrete crushing occurred and the confinement mechanism of spiral reinforcement did not work. The fracture of the PC bar on extreme tensile fiber become the trigger of the failure of the pile. All piles had a ductility factor around µ∆ = 4 in all cases. According to the seismic design code requirement, the spun piles were appropriate to be applied to a moderate seismic risk area. In application, due to seismic load, the piles should be designed remaining in the elastic state.