• Vol 9, No 1 (2018)
  • Civil Engineering

An Integrated System for Enhancing Flexural Members’ Capacity via Combinations of the Fiber Reinforced Plastic Use, Retrofitting, and Surface Treatment Techniques

Sri Tudjono, Han Ay Lie, Buntara Sthently Gan

Publish at : 27 Jan 2018 - 00:00
IJtech : IJtech Vol 9, No 1 (2018)
DOI : https://doi.org/10.14716/ijtech.v9i1.298

Cite this article as:
Tudjono, S., Lie, H.A., Gan, B.S. 2018. An Integrated System for Enhancing Flexural Members’ Capacity via Combinations of the Fiber Reinforced Plastic Use, Retrofitting, and Surface Treatment Techniques. International Journal of Technology. Volume 9(1), pp.5-15
Sri Tudjono Diponegoro University
Han Ay Lie Diponegoro University
Buntara Sthently Gan Nihon University
Email to Corresponding Author


This paper elaborates on the theoretical background, necessity, and techniques for enhancing the flexural capacity of a T-section member under combined bending and shear. The paper is based on a continuing research program seeking solutions to the design disparities arising from the introduction of new seismic codes and revised earthquake mapping prior to the tsunami and major earthquakes that occurred in South East Asia more than a decade ago. The research considered the application of external reinforcement using fiber-reinforced polymer (FRP) sheets, creating confinement in the shear area, and improving the tensile strength zone. The test results suggested that the methods sufficiently increased the load-carrying capacity to meet the new provisions, but they also showed that the optimum load-carrying capacity was not reached due to debonding of the FRP sheets in the tensile zone. The work was expanded to search for a surface treatment method that could shift the failure mode from debonding to FRP rupture by performing direct shear tests on treated FRP-to-concrete bond surfaces. Using the best surface treatment method, a failed member was straightened, retrofitted, and re-reinforced in terms of both shear and tension. The experimental results showed that the load-carrying capacity of the flexural member not only increased significantly, but the surface treatment methods also overcame the interface debonding problem. This research provides a method for upgrading the flexural capacity of T-section members designed prior to the tsunami and earthquakes of 2004, and it offers a solution for cracked section repair and restoration.

FRP reinforcement; Retrofitting; Surface treatment


This research considered the behavior of a T-section subjected to bending moments in amalgamation with maximum shear stresses, as would be the case in structures subjected to gravity and seismic loadings. The method provided sufficient improvement for typical sections to meet the newly introduced earthquake standards. The increase in the load-carrying capacity was mainly due to the additional tensile reinforcements provided by the FRP and the concrete compressive strength confinement from the external shear reinforcement. This external shear reinforcement led to a higher cylindrical compressive strength in the compression areas of the section. The shear reinforcement granted sufficient strength to carry the high shear stresses in the web of the section. The proposed surface preparation method by applying 2×0.5 mm grooves, 10 mm apart and perpendicular to the tension direction, was sufficient to prevent debonding under tensile-shear stress.

An approach to simultaneously optimizing the flexural capacity and performing retrofitting and FRP reinforcement was proposed. The revitalized members performed excellently in terms of both bending and shear. The members’ load-carrying capacity increased 99% in comparison with the controlling element BC.


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