Cold-Formed Steel (CFS) is widely used as secondary framing material. Nowadays, the research of CFS as a primary steel roof truss system became more favoured. Therefore, it is very important to understand the behaviour of CFS roof trusses due to the uncertainty of the configuration of CFS roof trusses can affect its structural integrity. The objective of this research is to investigate the effect of heel plate length and thickness to the ultimate load capacity of CFS roof truss system. Nine different lengths and thicknesses of heel plate specimens were fabricated and subjected to concentrated loads until failure. The highest ultimate capacity for the experiment was 28 kN. Local buckling of top chords adjacent to the heel plate was the primary failure mode for all the heel plate. The results showed that the increment of the length and thickness of the heel plate had slightly increased the ultimate capacity, but decrease the deflection. The behaviour of the numerical results showed a good agreement with the experimental results. Numerical load capacity was higher than experimental load by an average ratio of 1.12. The behaviour of the bottom chord for both results was different after the load reached 20 kN.

冷弯型钢（CFS）被广泛用作辅助框架材料。如今，作为主要钢屋架系统的CFS的研究变得越来越受欢迎。因此，了解CFS屋架的性能非常重要，因为CFS屋架的配置不确定性会影响其结构完整性。这项研究的目的是研究后跟板的长度和厚度对CFS屋架系统极限承载力的影响。制作了九种不同长度和厚度的后跟板样品，并对其进行集中载荷直至失效。实验的最高极限容量为28 kN。邻近后跟板的上弦的局部屈曲是所有后跟板的主要失效模式。结果表明，后跟板长度和厚度的增加略有增加了极限承载力，但减小了挠度。数值结果的行为与实验结果吻合良好。数值负载能力比实验负载高1.12的平均比率。载荷达到20 kN后，这两种结果的底部弦的行为都不同。