Unified Model Of Reinforced Concrete Members With Annular Section Under Combined Loads

Reinforced concrete members with annular section were widely used in special structure such as bridges,high voltage poles and oil platforms.By the influence action of earthquake and wind load,reinforced concrete structures were often damaged by combination of axial forces,shear forces,bending moment and torque.In existing researches and standards,there has already been excellent method about bearing capacity of the reinforced concrete structures under individual force.But the bearing capacity of the reinforced concrete members under combined loads was often calculated by empirical formula.There was also no unified theory and computational model of members with annular section.This article,which is based on limit equilibrium theory,studied on unified model of reinforced concrete members with annular sections under the combined loads of axial forces,shear forces,bending moment and torque.The specific content included the geometric form of the failure surface and the calculating formula of the bearing capacity.The first step was to deduce the dip angle of the damaged surfaces,by which the geometric form can be determined.The second step was to establish the equilibrium equation of the free body among the damaged surfaces,which could unify model of reinforced concrete members with annular sections under the combined loads.To verify the theoretical model and theoretical bearing capacity expressions of the reinforced concrete members with annular sections under the combined loads,this study made a comparison between the theoretical model and expressions and corresponding experiment results.Since there were few experimental data for the bearing capacity of the reinforced members with annular sections under the combined loads in existing study,this study used nonlinear finite element method to numerical analyzing.Then the unique theoretical expressions were simplified to the torsion situation,which were contrasted with the current standard of China.By being compared with experimental results and numerical simulation results,the advising theoretical expressions were well consistent,which can be reference in further engineering application and code reversion.