Analytical Investigation on the Structural Performance of RC Column with 3D Printed Concrete Permanent Formwork (2024-11)¶

Mechanical anisotropy of 3D printed concrete (3DPC) has been often considered harmful; however, its detrimental effect is not so serious or even negligible in some applications, such as permanent formwork made of 3DPC. Recently, several previous studies have demonstrated that 3DPC permanent formwork for reinforced concrete (RC) column construction can rather enhance the structural performance due to higher confinement effects from the permanent formwork. However, no comprehensive research has yet been conducted on effects of influential factors, including material properties, interlayer bonding properties, dimensions of 3DPC, bonding properties between 3DPC and inner core RC, and loading conditions. This research aims to evaluate effects of various factors on the structural performance of the RC column with 3DPC permanent formwork by using finite element method (FEM)-based nonlinear structural analysis. Specifically, the behaviors of 3DPC- RC columns under either uniaxial compression or reversed cyclic loading, which were reported in previous experimental studies, were investigated. Properly considering the material properties, structural dimensions, boundary and loading conditions of the columns, the FEM analysis could reproduce the force-displacement curves observed in experiment. The enhanced load-bearing capacity due to confinement effects could also be reproduced. The simulated failure modes also agreed with those in experiment. Subsequently, a parametric study using the FEM analysis was conducted varying material properties and bonding properties of 3DPC. The analysis results implied that the interlayer bonding properties have relatively small effects on the structural performance, especially in the case of the reversed cyclic loading. This is probably because the overall behavior is governed by the inner core RC and the effects of the thin permanent formwork are relatively limited. Therefore, 3DPC permanent formwork for RC column construction is a promising application in which detrimental effects of weak interlayers of 3DPC can be negligible and the overall structural performance can be even enhanced.