Title: Loading Rate Effect on Reinforced Concrete Walls with Low Aspect Ratios under High-Frequency Earthquake

Author(s): Jang-Woon Baek, Hyeon-Keun Yang, and Hong-Gun Park

Publication: Structural Journal

Volume: 117

Issue: 6

Appears on pages(s): 105-118

Keywords: cyclic loading; dynamic loading; high-frequency earthquake; low-rise walls; strain rate effect

DOI: 10.14359/51728059

Date: 11/1/2020

Abstract:
In regions with high-frequency earthquakes, the safety of nuclear power plants has been re-investigated considering the high-frequency contents. In this study, cyclic lateral loading testing was performed for low-rise reinforced concrete walls with aspect ratios of 1.0 and 0.5 to investigate the loading rate effect. For direct comparison, twin specimens that were subjected to either low-rate loading (1 mm/s [0.039 in./s]) or higher-rate loading (100 mm/s [3.93 in./s]) were tested. The test parameters include failure mode and reinforcement ratio. The test results showed that under higher- rate loading, the number of concrete cracks decreased while the crack width increased. However, the failure mode of RC walls was not significantly changed with varying strain rates (in the orders of 10–4 s–1 to 10–2 s–1). In the material test, under the higher rate loading, the yield strength of steel reinforcement was increased by approximately 3.3 to 8.3%. In the wall test, the strengths of the walls were increased by 9.9 to 12.2%, 4.0 to 17.5%, and 4.9 to 5.6% in flexure, shear, and shear-friction, respectively. The strength increase is mainly attributed to the increased yield strength of steel reinforcement under high rate loading.