Behaviour and design of composite walls under lateral loading and combined loading

This study aims to investigate the behaviour of concrete filled composite walls (CF-CWs) without any boundary elements under lateral loading and combined axial and lateral loading. Under this objective, an experimental programme was set covering both compact and slender CF-CWs utilising different connector types and arrangements. Specimens were designed with the aspect ratio (height to width ratio) of 1.9 so that the in-plane flexural behaviour dominated the failure modes. Meanwhile, for the combined loading, different axial load ratios (n) were applied to the specimens in order to investigate the effects of axial load and the relative lateral loaddisplacement responses. An extensive numerical study was conducted following the experiments with over one hundred three-dimensional finite element models. The simulations involved S690 high-strength steel together with high-strength concrete C100. The accuracy of the models was validated with the experimental results. The experimental and numerical outcomes were presented, analysed and discussed in detail. In addition, design provisions were proposed to calculate the in-plane flexural capacity of CF-CWs without boundary elements with different aspect ratios. The design recommendations can be applied to the CF-CWs with mild steel as well as highstrength steel up to S690. The validity of the recommendations was examined by this study and the available data from the previous literature.