Abstract: In order to solve the problem of large error when the constant value parameters of equivalent rectangular stress model in the code were used for circular section, the analytical solution of equivalent rectangular stress model parameters of circular section was derived. Based on the stress-strain constructive relationship in code, and according to all possible strain distributions in the axial-bending bearing capacity limit state, the analytical solutions of the stress full coefficient and resultant force position coefficient of the circular cross-sectional equivalent rectangular stress model were derived on the principle of equivalence. The calculation flow of analytical solution of bending and compression bearing capacity of arch concrete in compression zone was given. The analytical solution was verified by the numerical solution of strip method. The research shows that the position of the resultant force of the circular section concrete changes slightly and approaches to the centroidal axis. The safety requirements for vertical load-bearing small eccentric compression members are high, and the bearing capacity of small eccentric compression zone cannot be accurately calculated by the constant value parameters, so it should be calculated according to the analytical solution.

Key words: bridge and tunnel engineering; circular section; equivalent rectangular stress; analytical method; stress full coefficient; resultant force position coefficient

摘要： 为解决规范中等效矩形应力模型定值参数用于圆形截面时存在的误差较大问题，推导了圆形截面等效矩形应力模型参数解析解；由规范中的应力-应变本构关系，按照轴向-弯曲承载力极限状态所有可能的应变分布，以等效原则推导了圆形截面等效矩形应力模型的应力饱满系数和合力位置系数解析解，给出弓形混凝土受压区压弯承载力解析解计算流程；解析解通过条带法数值解验证。研究表明：圆形截面混凝土合力位置变化幅度小，趋近于形心轴；竖向承重小偏心受压构件安全度要求高，定值参数不能准确计算小偏心受压区承载力，应按照解析解计算。

关键词: 桥梁与隧道工程；圆形截面；等效矩形应力；解析法；应力饱满系数；合力位置系数