脱空对钢管混凝土单圆管拱肋面内承载力的影响

Influence of filling-incompletion on in-plane bearing capacity of single concrete filled steel tubular arch ribs

针对钢管混凝土拱肋普遍存在的核心混凝土脱空问题,借助通用结构有限元分析软件ANSYS,利用其自定义截面功能,对具有不同截面脱空率、拱肋脱空比以及脱空位置的抛物线单圆管钢管混凝土拱肋进行了面内竖向荷载作用下的双重非线性有限元分析。研究含钢率、荷载工况、矢跨比等参数一定的情况下,不同脱空形式对单圆钢管混凝土拱肋面内稳定性能的影响。研究结果表明,含钢率、荷载形式、矢跨比等参数一定的情况下,核心混凝土的脱空对拱肋弹性段刚度基本无影响;自弹塑性段开始,随截面脱空率及拱肋脱空比的加大,拱肋刚度削弱明显,面内承载力下降越多;脱空形式一定时,含钢率越小、竖向面内荷载沿拱肋分布越不均匀,拱肋后期刚度及面内承载力受脱空影响越显著。

Focusing on the popular issue of filling-incompletion among concrete filled steel tube( CFST) arch ribs,the influence of filling-incompletion on in-plane bearing capacity of parabolic single CFST arch rib was analyzed with ANSYS. By the custom function of beam section,finite element models with different types of filling-incompletion were produced. Different types of filling-incompletion were presented by such following parameters as void ratio of section,filling-incompletion proportion along arch rib and filling-incompletion location. Considering both the geometrical nonlinearity and the material nonlinearity of arch ribs,the behavior of CFST arch ribs under in-plane vertical load was obtained. With the same steel ratio,load case and rise-to-span ratio,the influences of different filling-incompletion on the in-plane bearing capacity of CFST arch ribs were analyzed. It is concluded that there is almost no influence on elastic stiffness of CFST arch ribs with filling-incompletion and the influence turns into more obvious after the beginning of elasto-plastic phase. The bigger the filling-incompletion ratio is,the lower the stiffness and bearing capacity of arch ribs are. With the same filling-incompletion type,the smaller steel ratio and the more uneven distribution of vertical loads,there is more significant influence on in-plane bearing capacity and arch ribs stiffness after ultimate point.