Pull-out behaviour of headed studs embedded in normal weight concrete at low temperatures

Steel–concrete composite (SCC) structures are increasingly being used in the Artic and cold regions. The pull-out performance of headed studs adopted as connectors in SCC structures determines transverse shear resistance of these structures and prevents their uplifting. In this study, the tensile behaviour of headed studs embedded in normal weight concrete (NWC) slabs exposed to the Artic low-temperature environment was explored. Firstly, 16 pull-out tests of headed-stud-containing specimens were carried out to explore the influence of the low temperature level, concrete grade, and ratio of the effective embedment depth of stud to its diameter (hef/d) on the tensile capacity of headed studs exposed to low temperatures. Results obtained from experiments revealed the failure modes, tensile-bearing capacity of headed studs embedded in NWC, and their key influencing parameters. In particular, the results revealed that low temperatures improved the tensile-bearing capacity of headed studs because of the improved strengths of NWC and stud material. The hef/d ratio at which the failure mode changed from the breakout of concrete to the tensile fracture of stud shank varied from 3.56 to 5.75 depending on the low temperature level. Finite element models (FEMs) were also established for the simulation of pull-out behaviour of headed-stud-containing specimens exposed to low temperatures. The test results helped checking the accuracy of developed FEMs. Finally, design equations in various codes were adopted to estimate ultimate tensile resistances of headed studs embedded in NWC at the Arctic low temperatures and predictions were verified against 16 test results. All these findings are expected to contribute to the development of prediction equations for SCC structures at low temperatures.