Study of formwork pressure of column under ultra-deep vibration

Abstract

Only a few research studies have been conducted into the lateral pressure on formwork of concrete subjected to ultra-deep vibration, and great differences exist in the determination of form pressures and vibration depth in the current national codes. This paper presents experimental results of five 60 cm × 60 cm × 300 cm specimens of concrete columns to investigate the effect of ultra-deep vibration on the form pressure. Based on the vibrating liquefaction and hydrostatic pressure balance theory, a calculation model of the form pressure under ultra-deep vibration is established and a relevant calculation formula is proposed. The calculation results are compared with the test data. The results show that the vibration depth has a significant effect on the lateral pressure of freshly placed concrete. The pressure at the vibrator head does not vary linearly with the increasing vibration depth and is smaller than the equivalent hydrostatic pressure exerted by fresh concrete. It is proved that the proposed calculation method gives a reasonable prediction of the lateral pressure of columns at the head location of ultra-deep vibration.