Effect of Impact Load on Splice Length of Reinforcing Bars

• Published in: International journal of concrete structures and materials Vol. 14; no. 5; pp. 711 - 727
• Main Authors: Hwang, Hyeon-Jong, Yang, Fan, Zang, Li, Baek, Jang-Woon, Ma, Gao
• Format: Journal Article
• Language: English
• Published: Singapore 한국콘크리트학회 01.12.2020; Springer Singapore; Springer; SpringerOpen
• Subjects: Building Materials; development length; drop hammer test; Engineering; impact load; lap splice test; RC beam; Solid Mechanics; strain rate effect; Structural Materials; 토목공학; South Korea; China; strain rate effect; drop hammer test; lap splice test; impact load; bond strength; RC beam; development length
• ISSN: 1976-0485; 2234-1315
• DOI: 10.1186/s40069-020-00414-z

Impact loading damage of reinforced concrete (RC) members deteriorates bond strength of reinforcing bars. To understand the effect of strain rate on the bond strength of reinforcing bars in RC beams under impact load, drop hammer test was performed on twenty-four simply supported RC beams with lap spliced bars at the mid-span. The test parameters were reinforcing bar diameter, splice length, drop height, and hammer mass. The dynamic responses including the impact load history, mid-span deflection history, crack distribution, and strain history of reinforcing bar were evaluated. Although the designed bar development length was 31–69% of the requirement of current design codes under static load, the tensile strength of bar splices was greater than the dynamic yield strength when subjected to large impact energy under impact load. On the basis of the test results, existing design equations for the bar development length under static load were modified to consider the impact loading effect on the bond strength. Factors related to the strain rate effect of materials, impact damage, and impact energy loss were proposed. The prediction of the proposed method agreed well with the tensile strength of bar splices under impact load.