Axial compressive behavior of circular UHPC filled high-strength steel tube (UFHST) short columns

Abstract

There is an increasing interest in using ultra-high performance concrete (UHPC) and high-strength steel in steel-concrete composite structures. This paper makes a contribution towards this by experimentally investigating the axial compressive behavior of circular UHPC filled highstrength steel tube (UFHST) short columns. A total of nine UFHST columns were tested under axial compression. The test parameter was the steel tube diameter-to-thickness ratio (13 to 32). The steel yield stress was 961 MPa (139.35 ksi), and the compressive strength of UHPC (without steel fibers) was 142 MPa (20.59 ksi). Results from the test indicated that the strength of the UFHST columns increased with decreasing steel tube diameter-to-thickness ratios. Two limit states were observed from the tests, i.e., shear failure of the concrete infill and local buckling of the steel tube. The governing limit states depend on the steel tube diameter-to-thickness ratio. Moreover, the strength enhancement and ductility of UFHST columns were discussed by using performance indices such as concrete contribution ratio (CCR), strength index (SI) and ductility index (DI). It was demonstrated that UFHST columns with thicker tube wall had better ductility, while leading to less strength enhancement or composite action.

Bearing behavior of high-performance concrete-filled high-strength steel tube composite columns subjected to eccentrical load

“…In 2016, tests of 8 high-strength concrete-filled high-strength square steel tube composite columns under bending load were carried out by Li et al (2019), and the results showed that the ultimate bearing capacity of composite columns under pure bending load increased gradually with the increasing of steel ratio and yield strength of steel tube, and the ultimate bearing capacity of composite columns obtained by finite element (FE) analysis was in good agreement with the calculations of EC4. In 2020, Tests and FE analysis on ultra-HPC-filled round high-strength steel tube composite stub columns subjected to axial load were conducted by Wei et al (2019),and the results showed that highstrength steel tubes provided more effective restraint for ultra-HPC, so high-strength steel tube was a better match with ultra-HPC. In 2021, FE analysis on the bearing capacity of hollow GFRP pipe-concrete-steel tube composite long columns subjected to eccentrical load was carried out by Ji et al (2021d), and the results showed that with the increasing of thickness of GFRP tube, steel tube, and cubic compressive strength of concrete, the ultimate eccentrical compression bearing capacity increased gradually, finally a formula for the bearing capacity of such composite columns under eccentrical load was proposed by statistical regression.…”