Cyclic beam bending test for assessment of bond-slip behavior
Bond between reinforcement and concrete is one of the most important aspects in structural response of reinforced concrete (RC) members. Basic RC theories assume compatibility of strains between concrete and steel which is valid only if a perfect bond exists between the two materials. Therefore investigating bond properties under different loading conditions and considering various variables is of great importance. Although researchers have extensively explored bond-slip relationships for different concrete and steel types under monotonic loading using different test setups, less is reported on bond properties under reversed cyclic loading. Modified pullout tests have previously been used to investigate cyclic bond-slip relationships; nevertheless these tests do not represent the actual bond behaviour inside RC members subjected to flexural actions. This study focuses on developing a specific test setup and designing a beam specimen for cyclic bond test following RILEM recommendations for monotonic assessment of bond properties, which require a two-point loading (four-point bending) setup. The main challenge was to design a stable cyclic test setup in order to ensure no additional forces generated in the system during the test. High strength self-compacting concrete (HSSCC) beam specimens were chosen for the test; the beam specimens were designed in such a way that they could withstand load reversals.