Experimental Study on Screw Connections of Aluminium Roof-Purlin Systems

Aluminium roofs have many superior characteristics compared to steel roofs, such as a higher strength-to-weight ratio, greater corrosion resistance, better formability, and easier recyclability. These characteristics make aluminium roofs a preferable option in engineering construction. However, the thermal expansion coefficient of aluminium is twice that of steel, resulting in significant thermal loads generated at the connections between the roof and the purlins, especially in extreme weather conditions. Due to the unique characteristics and features of the roof profiles, there is typically a range (around 52 mm) between the ribs of the curved aluminium roof panels and the screw-connected purlins. This spacing distinguishes this connection type from traditional connections that rely on direct shear connections without any spacing. This research conducted laboratory experiments to investigate the performance of such connections. The results from the screw connection tests revealed that the screws bend due to the moment induced by thermal loads, altering the loading effect with tear failure to be the predominant failure mechanism on the aluminium panels. Additionally, monotonic and cyclic loading tests provide insight into the force-displacement relationships of multiple screws subjected to single- direction loads. These findings have practical implications for designing more resilient aluminium roof fixing systems.