Effects of steel fibers on failure mechanism of S-UHPC composite beams applied in the Arctic offshore structure

A novel steel-concrete-steel composite structure constructed using ultra high-performance concrete (forming an S-UHPC composite structure) was applied in Arctic offshore structures. This type of structure can withstand ice pressure derived from impinging sheet ice in the Arctic region. In this study, the failure mechanism of S-UHPC composite beams was explored experimentally and analytically, considering the effects of steel fibers in UHPC. Five groups of push-out tests were conducted to reveal the interfacial performance between steel plates and UHPC. Static tests on S-UHPC composite beams were performed to study their structural behaviors. The results indicate that steel fibers have a significant effect on the failure modes, slippage behavior, and mechanical behavior of the S-UHPC composite beams. Furthermore, on the basis of test results, finite element (FE) models of the push-out tests and static tests of the S-UHPC composite beams were developed and validated. Further, a parametric study was carried out to summarize the failure modes of the push-out tests and to explore the influence mechanism of steel fibers on the structural behavior of the S-UHPC composite beams. Finally, an analytical model for predicting the ultimate strength of S-UHPC composite beams was proposed and compared with existing design codes.