Long-term performance of steel-concrete composite wall panels under axial compression

Innovative steel-concrete composite (SCC) walls are increasingly becoming a popular choice in low-to-high-rise buildings due to their high load-bearing capacity and convenience of construction. The long-term behaviour of these walls is therefore of great significance to the serviceability behaviour and this paper attempts to address this important issue. The paper firstly discusses the scarcity of experimental investigations on the long-term behaviour of SCC walls, and then presents an experimental program for both plain concrete and SCC wall panels under sustained axial loading, with a 20% axial load ratio for the concrete. The ultimate axial strength test is conducted after the long-term tests of SCC wall panels featuring headed studs of different configurations. The long-term outcomes correspond well with the ACI209 predictive model, providing information on assessing creep and shrinkage effects over extended durations. It is noted that SCC specimens without headed studs demonstrate a considerable reduction in both final shrinkage strains and creep coefficients relative to plain concrete specimens, and the presence of headed studs leads to further reductions. In addition, this paper explores the effect of different types of headed stud arrangements on the creep and shrinkage behaviour. However, no significant influence is observed from staggered arrangements versus parallel arrangements. The ultimate axial strength test shows a reduction in the ultimate axial strength in the loaded specimens compared with the unloaded specimens, while the failure modes are similar among different specimens, which are local buckling of steel faceplates. This paper concludes with a comparative analysis, comprising both long-term and ultimate axial strength test results against prevailing building standards, providing valuable insights for future design and construction of SCC walls.