This paper aims to investigate the performance of concrete which incorporates plastic optical fibre (POF). In this study, the performance of light-transmitting concrete (LTC) specimens made by using different dosages and spacings of POF is investigated. The properties of POF are investigated and discussed. The experimental results show that LTC can provide a high light-transmitting ratio. This paper contributes to the determination of new alternatives for sustainable construction around the world. LTC can help to reduce power consumption in buildings by allowing natural light to shine into the building interior through external walls. This paper adds distinctive knowledge to the area of sustainable construction by studying the effect of POF on the properties and performance of concrete. In addition, the use of POF in concrete can lead to an increase in compressive strength.

Concrete-filled steel tube (CFST) structural members have been widely used in engineering projects for their superior strength and ductility. However, the different lateral dilation characteristics between concrete infill and steel tube have caused imperfect composite interaction during the early loading stage. To overcome this issue, external steel confinements in the form of rings and spiral were previously suggested to minimise the lateral expansion of the steel tube and enhance the concrete confinement effects. This study presented the analytical behaviour of circular CFST short columns with an external ring or spiral confinements which are subjected to axial loading. An explicit finite element (FE) model was developed and verified based on previous experimental findings. Besides that, this study analysed the failure modes, axial load–strain relationship, stress distributions, and bond strength of the composite column components. Parametric analysis was also undertaken to evaluate the impact of material strengths, total steel ratio, and diameter-to-thickness ratio. The results suggest that the use of external steel confinement can enhance the compressive behaviour of CFSTs better than increasing the thickness of the steel tube when using the same steel ratio. Finally, simplified design formulations were developed to accurately calculate the ultimate capacity of CFST columns with and without external steel confinement.

This research collected and summarized a total of 455 experimental tests of axially loaded square and rectangular concrete-filled steel tubular (CFST) stub columns. The recently published papers were used to evaluate the current design equations from four international standards, namely the American Concrete Institute (ACI) code, British Standard (BS5400), Chinese standard (BDJ13-51), and Eurocode 4 (EC4). It was found that the results obtained from the codes have appreciable differences and could be improved, especially for the specimens fabricated using high-resistance materials. Therefore, new empirical equations were proposed based on the four standard formulas and the wide range of previously available experimental data to provide more accurate estimations. The proposed equations could predict an average sectional capacity of only 0.1% lower than the experimental results, with better data scattering than the existing equation’s results.