The analysis and design of structures sensitive to second order effects require the consideration of initial imperfections. Scaffold structures, due to their low stiffness, are very sensitive to second order effects. The accuracy of the design of these structures relies in part on the estimation of initial imperfections affecting the structure. In the 1960s, the C.E.C.M., the European Convention of Steel Construction, carried out a series of experimental tests to determine the degree of initial imperfections of each type of cross-section. Five buckling curves were established. The European design code for steel structures, Eurocode 3 Part 1-1, classifies hot-rolled hollow tubular sections as profiles with few imperfections, i.e. buckling curve ‘a’, and cold-formed sections as sections with many imperfections, i.e. buckling curve ‘c’. A test campaign was conducted to analyse the experimental buckling behaviour of hot-rolled and cold-formed hollow sections of scaffold structures. Twenty-nine buckling tests on simply supported members and nine buckling tests on scaffolding ladders, from various European suppliers, were carried out. Statistical studies of the experimental results point out that the estimate of the initial imperfection currently defined for the hot-rolled and cold-formed tubular sections is far too penalizing for sections used in scaffolding.

对二阶效应敏感的结构的分析和设计需要考虑初始缺陷。脚手架结构由于其低刚度而对二阶效应非常敏感。这些结构设计的准确性部分取决于对影响结构的初始缺陷的估计。在1960年代，CECM（欧洲钢结构公约）进行了一系列实验测试，以确定每种横截面的初始缺陷程度。建立了五个屈曲曲线。欧洲钢结构设计规范，欧洲规范3第1-1部分，将热轧空心空心型材归类为具有很少缺陷的型材，即屈曲曲线“ a”，将冷弯型材归类为具有很多缺陷的型材，即屈曲曲线“ C'。进行了一项测试活动，以分析脚手架结构的热轧和冷弯空心型材的实验屈曲行为。对来自欧洲多家供应商的简单支撑构件进行了29次屈曲测试，并对脚手架梯进行了9次屈曲测试。对实验结果的统计研究指出，目前对热轧和冷弯管状型材的初始缺陷的估计对于脚手架型材来说太过不利了。