中文摘要：

使用一种高效的跟踪策略对拱的平面内弹塑性极值点屈曲和二次分岔屈曲的荷载一位移曲线的全过程进行跟踪分析，得到了跨中集中荷载和全跨均布荷载作用下，相同截面不同矢跨比的拱的弹塑性极值点屈曲荷载、二次分岔屈曲荷载和半跨均布荷载作用下的极值点屈曲荷载。研究表明，对于弹塑性拱结构，跨中集中荷载和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，必定先于极值点屈曲发生。相同截面的弹塑性拱的极值点屈曲荷载，在跨中集中荷载作用下矢跨比为0．2的拱的极限承载力最大；在半跨均布荷载作用下，矢跨比为0．23的拱的极限承载力最大；全跨均布荷载作用下，矢跨比为0．1的拱的极限承载力最大。对于弹塑性拱的二次分岔屈曲极限承载力，在跨中集中荷载作用下，矢跨比为0．2的拱的极限承载力最大；全跨均布荷载作用下，矢跨比为0．1的拱的极限承载力最大。最后求得全跨和半跨均布荷载作用下具有不同长细比、不同矢跨比的拱的弹塑性极限承载力并且回归成实用计算公式以便于实际工程设计中查询。

英文摘要：

The in-plane primary buckling and secondary bifurcation buckling load-displacement equilibrium paths, of the elastic-plastic arches with same sections and different rise-span ratios are traced with a high-efficient tracing strategy. The elastic-plastic primary buckling load and secondary bifurcation buckling load under full-span distributed load, and concentrated load at the top of arch, and the primary buckling load under half-span distributed load are obtained. The calculation results show that the secondary bifurcation buckling is always the most dangerous buckling type when the arch is under full-span distributed load and concentrated load at the top of arch for elastic-plastic arch. The secondary bifurcation buckling will always happen before the primary buckling. For primary buckling load of the same section arches, the ultimate load carrying capacity of arch with 0.2 rise-span ratio is the biggest one under concentrated load at the top of arch. The ultimate load carrying capacity of the arch with 0.23 rise-span ratio is the largest one under half span distributed load and that of the arch with 0.1 rise-span ratio is the largest under full-span distributed load. For secondary bifurcation buckling load, the ultimate load carrying capacity of the arch with 0.2 rise-span ratio is the largest one under concentrated load at the top of arch and that of the arch of 0.1 rise-span ratio is the largest one under full span distributed load. Finally the elastic-plastic ultimate load carrying capacity of elastic-plastic arch with different slenderness and rise-span ratios under full and half span distributed load were calculated and formulated for engineering reference.