[Structural Institute]

Xu Long, Chun-Yan Wang, Pei-Zhi Zhao, Shao-Bo Kang. Bond Strength of Steel Reinforcement under Different Loading Rates. Construction and Building Materials, 2020, 238, 117749

Keywords: Bond-slip behaviour, Embedded steel reinforcement, Pull-out test, Loading rate, Strain rate

High Lights: 

The bond strength between steel reinforcement and concrete could be increased by increasing the loading rate.

The strain rate attained its maximum value at the loaded end, and decreased towards the free end.

The mechanisms governing the higher bond strength under dynamic loads were identified based on test results.

Abstract: 

This paper addresses the bond strength of steel reinforcement subject to different loading rates. In the experimental programme, a total of 15 pull-out tests were conducted on steel reinforcing bars with various embedment lengths. The loading rate varied from 0.1 mm/s to 100 mm/s. The applied load, slip at the loaded end and strains along the embedment length of steel reinforcement were measured during testing. Bond stresses and strain rates along the embedment length of reinforcement were calculated from the measured strains. Test results suggested that a higher loading rate could increase the bond stress between steel reinforcement and concrete. The increase in bond stress was mainly induced by the rapid slip and the relatively high dynamic yield strength of reinforcement, depending on the stress state of the reinforcement. Finally, conclusions were drawn from the experimental results to facilitate the analysis of the bond-slip behaviour of steel reinforcement under high loading rates.

Resource：https://www.sciencedirect.com/science/article/pii/S0950061819332027