Search

This study examines the behavior of circular concretes externally confined by green sustainable WHBR FRP containing water hyacinth fiber ropes and bio-resin. This study principally purposes to discover the axial stress-strain relationship behavior of WHBR FRP-confined circular concrete. A total of 10 circular concretes with a dimension of 150×300 mm were cast, strengthened with one to four layers of WHBR FRP, and tested under compression. The stress and the deformability of WHBR FRP-confined circular concretes were observed to be increased along with the addition of WHBR FRP layers. The accurateness of existing ultimate stress and strain models of natural FRP-confined circular concrete was evaluated using the test results. Indicating the need for the newly developed models to precisely predict the ultimate stress and strain values of WHBR FRP-confined circular concrete, newly developed models were developed to be precise in estimating the ultimate stress and strain of WHBR FRP-confined circular concrete. Keywords concrete, confinement, disaster risk reduction, stress-strain, water hyacinth fiber.

RC structures with poorly confined columns have been known to have poor performance during earthquake events. Brittle failures of columns with low ductility can lead to progressive overall building collapses. Many confining techniques have been proven to be successful in retrofitting circular columns. However, for square or rectangular columns, providing effective confining stress by the external retrofitting method is not a simple task due to the high stress concentration occurring at the column's corners. In this paper, an analytical model for the axial stress-strain relationship of square concrete columns confined only by external steel collars has been developed. The combined effect of conventional internal stirrups and the external steel collars on the improved stress-strain relationship has been also developed analytically and proposed as the retrofit design approach. Comparison with experimental results has shown that the axial stress-strain relationship of square RC columns could be well predicted by the proposed retrofit design approach. [ABSTRACT FROM AUTHOR]

The development of the use of natural fiber as a constituent material for FFP as an external concrete retrofit that is environmentally friendly and affordable price has been quite developed. One plant that grows massively in Indonesia and can be extracted into fiber is water hyacinth. This plant will be extracted into fiber through three variations, namely mechanical, boiling, and natural alkali, by using bio-resin to produce WHBR (Water Hyacinth and Bio-Resin) FRP in the form of rope and weave. The tensile behavior of the obtained WHBR FRP will be investigated against ASTM A931-18 and ASTM D3039 requirements. The results of the investigation are compliance with failure criteria, the impact of the tensile test result on compliance with failure criteria, and the impact of pattern-delignification on tensile strength performance. In this study, it has been found that the boiling treatment-plain woven variation of WHBR FRP has the best properties and it is recommended as an external concrete retrofit material for future studies. [ABSTRACT FROM AUTHOR]

One of the crucial problems caused by the COVID-19 pandemic is the increase in the number of disposable plastic wastes, especially bubble-size plastic straw waste. The use of recycled fiber as a material of fiber-reinforced polymer composites for concrete strengthening can be an alternative to recycling disposable plastic wastes, especially in Indonesia. The use of fiberreinforced polymer made from woven bubble-size plastic straw waste fibers that are bonded with epoxy has been found out to be able to alternate the axial deformability and ultimate compressive strength of confined circular concrete. The axial stress-strain behavior shows a trilinear trend with two ascending parts and one descending part. Adding more FRP layers has also improved significantly the axial deformability and ultimate compressive strength. Based on test results from this study for bubble-size plastic straw waste fiber-reinforced polymer, new models are created to forecast both the ultimate compressive strength and the strain. The results of the experimental analysis have shown that four layers application of bubble-size plastic straw waste fiberreinforced polymer confined circular concrete is effective enough to increase the strength of concrete up to 42.69 % of the initial strength of concrete. [ABSTRACT FROM AUTHOR]