Q420钢板式加劲肋局部稳定试验与计算方法

Local Stability Test and Calculation Method of Q420 Steel Plate Stiffener

板式加劲肋作为开口加劲肋中最基本的形式,主要以局部失稳破坏为主.为研究开口加劲肋的局部稳定性能,分别设计了变化板肋厚度与高度两组Q420开口板肋加劲板试件进行轴压试验,并建立相应的有限元模型,得到板式加劲肋、三边简支板的局部稳定简化计算公式.试验与分析研究表明:当板肋宽厚比小于16时,出现板肋与被加劲板的同时屈曲破坏,反之,则出现板肋的局部屈曲破坏.随着板肋宽厚比的增大,试件极限平均应力逐渐减小,破坏时的失稳变形现象更明显.采用构件中板式加劲肋所拟合的三次多项式曲线在相对宽厚比超过1.08后高于其他规范曲线,三边简支一边自由的简化模型所拟合的曲线在相对宽厚比超过1.32后高于欧拉曲线,在整个相对宽厚比范围内均高于我国钢桥规范与日本规范曲线.采用构件中板式加劲肋拟合公式可以更精确地计算实际试件承载力;而采用三边简支板拟合的公式则有更高的安全冗余,推荐采用三边简支板拟合公式进行设计.

Plate stiffener is the most basic form of open stiffener,and its local instability is the main failure mode.In order to study the local stability of plate stiffener,two groups of Q420 open flat plate stiffened panel speci‐mens with different thicknesses and heights were designed for axial compression tests,and the corresponding finite element model was established.The simplified calculation formulas for the local stability of the plate stiffener and tri‐lateral simply supported plate were obtained.The experimental and analytical results show that:when the width-to-thickness ratio of plate stiffener is less than 16,the simultaneous buckling failure of plate stiffener and stiffened plate occurs,on the contrary,the local buckling failure of plate stiffener occurs;With the increase of the width-to-thickness ratio of plate stiffener,the ultimate average stress decreases gradually,and the instability deformation of the specimen becomes more obvious.When the relative width-to-thickness ratio exceeds 1.08,the fitted cubic poly‐nomial fitting curve of the plate stiffener in the member is higher than that of other code curves;When the relative width-to-thickness ratio exceeds 1.32,the fitted cubic polynomial fitting curve of trilateral simply supported plate is higher than that of Euler curve,and it is higher than the curves in Chinese steel bridge code and Japanese code in the whole range of relative width-to-thickness ratio.The fitting formula of plate stiffener in the member can accu⁃rately calculate the bearing capacity of the actual specimen,and the fitting formula of a trilateral simply supported plate is safer.It is recommended to use the fitting formula of a trilateral simply supported plate for design.