均布荷载下拱的弹塑性二次分岔屈曲性能初探

使用一种新的屈曲路径跟踪策略,对拱在平面内的弹塑性极值点屈曲和二次分岔屈曲全过程进行跟踪分析,得到全跨均布荷载作用下材料、截面相同而矢跨比不同的拱的弹塑性极值点屈曲荷载和二次分岔屈曲荷载,以及半跨均布荷载作用下其极值点屈曲荷载.研究结果表明：对于弹塑性拱结构,在全跨均布荷载作用下,二次分岔屈曲总是最危险的屈曲形式,其发生必定先于极值点屈曲.对于材料、截面相同,矢跨比0.1～0.5的拱,半跨均布荷载作用下矢跨比0.23的拱极值点屈曲极限承载力最大;全跨均布荷载作用下,矢跨比0.1的拱极值点屈曲和二次分岔屈曲极限承载力均大于其他拱.将得到的全跨和半跨均布荷载作用下不同长细比、不同矢跨比拱的弹塑性极限承载力计算结果归纳总结,得到极限承载力简化计算公式,可以直接查用,便于工程设计中使用.

Secondary bifurcation buckling behavior of elastic-plastic arch under uniform load distribution

The whole processes of a in-plane primary flexuosity and a secondary bifurcation flexuosity were traced by a high-efficient tracing strategy. The elastic-plastic primary buckling load and the secondary bifurcation buckling load under a full-span load distribution and the primary buckling load under a half-span load distribution were obtained. The calculation results show that the secondary bifurcation flexuosity is always the most dangerous buckling type when the arch is under a full-span load distribution for an elastic-plastic arch. The secondary bifurcation will always happen be- fore the primary flexuosity. For a primary buckling load, the limit load carried capacity of the arch of 0.23 ratio-span is the biggest one under a half span load distribution and that of the arch of 0.1 rise-span ratio is the biggest under a fullspan load distribution. For a secondary bifurcation buckling load, the limit load carried capacity of the arch of 0.1 rise- span ratio is the biggest one under a full span load distribution. Finally the elastic-plastic limit loads carried capacities of arch under a full and half span load distributions were calculated and their mathematical models were induced for engineering reference.