Behaviour and Design of Steel-Concrete Composite Walls and Coupled Wall-Frame Structures Incorporating Long-Term Effects and Elevated Temperatures

Abstract

This thesis firstly presents an experimental exploration into the long-term behaviour of steel-concrete composite (SCC) walls subjected to sustained axial loads. The long-term experimental program comprises 19 scale-down specimens, including both plain concrete and SCC wall panels. Following the 199-day long-term loading tests, the ultimate axial strength test was performed on SCC panels with various headed stud configurations. The test results were then compared against current building standards, providing information on assessing long-term effects on the serviceability and ultimate strength design of SCC walls over extended durations.

Subsequently, this thesis numerically examines the fire-resistance behaviour of SCC walls. An advanced finite element (FE) modelling approach was developed, followed by a comparative analysis of the fire resistance period (FRP) between SCC and reinforced concrete walls with the equivalent core concrete thickness. Moreover, an extensive parametric study involving 234 FE models of SCC walls highlighted the limitations of current building standards in predicting the FRP. Consequently, new design equations, formulated from a best-fit analysis of the modelling results, were introduced to provide more accurate FRP estimates.

The final part of this thesis investigates the reinforcing effect of SCC walls on the lateral behaviour of SCC frames through experimental and numerical studies on the innovative SCC coupled wall-frame structures. The experimental study includes quasi-static lateral load testing on one single-storey bare frame and three single-storey coupled wall-frame structures, leading to the development of FE modelling methods. The parametric study was conducted to explore the critical design parameters for coupled wall-frame structures. Moreover, the inter-storey drift ratios of these structures were compared with the current building standards, offering a comprehensive assessment of their performance.