嵌套加强的LQ550高强冷弯薄壁C型钢连续檩条受力性能研究

Load⁃carrying behavior of LQ550 high strength continuous purlin with cold⁃formed thin⁃walled C⁃section using embedded strengthening

为提高LQ550级高强冷弯薄壁C型钢连续檩条的承载能力,采用在支座处嵌套的方法来加强连续檩条。对未加强和采用两种嵌套方式加强的檩条共7组试件进行三点受弯试验,得到了试件的承载性能和破坏形态,试验结果表明加强后的试件出现跨中局部屈曲和嵌套端部局部屈曲两种破坏形态。采用ABAQUS软件建立了非线性有限元模型对嵌套加强的檩条进行数值模拟,有限元分析得到的承载力和破坏形态与试验结果吻合良好,验证了有限元模型的准确性。基于验证的有限元模型,分析了两种嵌套方式和不同嵌套长度对檩条承载力的提升,且表明嵌套檩条的长度宜取为连续檩条跨度的1/5~1/4。

In order to improve the load⁃carrying capacity of LQ550 high strength continuous purlin with cold⁃formed thin⁃walled C⁃section,a novel embedded strengthening technique was introduced to reinforce the continuous purlins near the supports.A total of seven groups of continuous purlin specimens including those with two different embedded strengthening forms were tested subjected to three⁃point loading,and the load⁃carrying behavior and the failure modes were obtained.The experimental results show that the strengthened purlins displayed two local buckling failure modes including the one at mid⁃span and the other adjacent to the strengthened segment.A nonlinear finite element(FE)model was established using the ABAQUS software and was used to reproduce the load⁃carrying behavior of the tested continuous purlins.The numerically predicted failure mode and load⁃carrying capacities were in good agreement with the test results,enabling the validation of the developed FE model.Using the validated FE model,the influences of the two embedded strengthening techniques and the strengthening length on the load⁃carrying capacity of purlins were examined.It has been demonstrated that the strengthening length of continuous purlins can be taken as 1/5~1/4 of the span.