Steel-concrete composite girders with corrugated steel webs: Accordion effects

The accordion effect of corrugated steel webs is widely recognized for significantly improving the prestressing efficiency of steel-concrete composite girders. Nevertheless, the negative influence of the accordion effect weakens the flexural capacity of composite girders. The conventional flexural design always ignores corrugated steel webs due to the accordion effect. Therefore, accounting for the accordion effect is an effective way to achieve economical structural design and obtain an accurate evaluation of the flexural capacity of composite girders. This paper experimentally investigates the accordion effect in steel-concrete composite girders with corrugated steel webs. Three evaluation indexes, involving the reduction factor η, web participation t_w,eff/t_w, and additional flexural capacity ratio δ, are introduced to quantify the accordion effect from different aspects. Subsequently, parametric studies are conducted to investigate the effects of steel strength, concrete strength, web height-to-thickness ratio, and steel flange-to-web thickness ratio. The research results indicate that about 20 % of the girder's flexural capacity is reduced by the accordion effect. Corrugated steel webs can contribute up to 30 % of the additional girder's flexural capacity, and the effective web thickness can reach up to 0.4 times the actual web thickness. Thus, completely ignoring the web's flexural contribution will lead to the conservative estimation of the girder's flexural capacity and uneconomical structural design. Furthermore, a flexural analytical model with satisfactory prediction efficiency is proposed for quantifying the accordion effect and estimating the ultimate flexural capacity of steel-concrete composite girders with corrugated steel webs considering the accordion effect.