Experimental study on flexural behavior of ECC/RC composite beams with U-shaped ECC permanent formwork

Abstract

To enhance the durability of a reinforced concrete structure, engineered cementitious composite (ECC), which exhibits high tensile ductility and good crack control ability, is considered a promising alternative to conventional concrete. However, broad application of ECC is hindered by its high cost. This paper presents a new means to address this issue by introducing a composite beam with a U-shaped ECC permanent formwork and infill concrete. The flexural performance of the ECC/RC composite beam has been investigated experimentally with eight specimens. According to the test results, the failure of a composite beam with a U-shaped ECC formwork is initiated by the crushing of compressive concrete rather than debonding, even if the surface between the ECC and the concrete is smooth as-finished. Under the same reinforcement configurations, ECC/RC composite beams exhibit increases in flexural performance in terms of ductility, load-carrying capacity, and damage tolerance compared with the counterpart ordinary RC beam. Furthermore, a theoretical model based on the strip method is proposed to predict the moment-curvature responses of ECC/RC composite beams, and a simplified method based on the equivalent rectangular stress distribution approach has also evolved. The theoretical results are found to be in good agreement with the test data.

Keywords

engineered cementitious composite (ECC) / durability / ECC/RC composite beam / permanent formwork / flexural performance / theoretical method

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Acknowledgments

The authors acknowledge the funding supports of National Key Research and Development Plan, China (2016YFC0701400, 2017YFC1500700), and the National Natural Science Foundation of China (Grant No. 51778462).

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