Experimental Study on Axial Compression Performance of UHPC Columns with Circular Hollow Section

To promote green bridge design and rapid construction, this study proposes using ultra-high-performance concrete (UHPC) hollow sections to replace conventional solid sections in pier columns, focusing on the basic axial compressive capacity. Six scaled UHPC and three NC hollow columns were designed and fabricated* considering the effects of different materials, restraint conditions, and diameter-thickness ratios on the load capacity and damage pattern. First, the mechanical properties of this batch of UHPC were tested, based on which a suitable constitutive law for UHPC was proposed and assigned to the subsequent finite element models. The subsequent axial compression experiment showed no cracking in the UHPC specimen and vertical cracks passed through the NC specimen. The influence of different stirrup restraints on the initial stiffness of the specimens was small, and the load capacity was relatively large; the better the restraint effect, the higher the load capacity. For the two groups of hollow column specimens with equal sectional areas, the smaller the diameter-thickness ratio, the higher the load capacity. When the diameter-thickness ratio changes from 9. 5 to 7, the load capacity of the specimens increases by 8. 8% on average. The increase in column load capacity is not proportional to the increase in material strength. Finally, a finite element analysis model was established according to the proposed constitutive law and compared with the measured results, which show that the load-displacement curves match well with the tests. The research findings can provide inputs for the design of prefabricated UHPC circular hollow piers for future applications. © 2023 Xi'an Highway University. All rights reserved.