For reinforced concrete arch bridges formed by the strong skeletal method, when calculating the non-strong skeletal structure, only the steel tubes are considered as ordinary reinforcement without accounting for composite force effects, which has a minimal impact and leans towards safety. However, for strong skeletal structures, if composite force effects are not considered, the calculation results are excessively conservative. In this paper, taking the Xining River Extra Large Bridge as a background, the influence of composite force effects of the strong skeletal structure on the ultimate load-bearing capacity of the arch ring is analyzed under the influence of dual nonlinearity.