Abstract: Reinforced concrete structural members with annular section are commonly used in concrete chimneys, concrete pipes and elevated water tanks, as well as in large bridge columns and offshore platforms. So it is very necessary to study the mechanism of reinforced concrete annular section structures subjected to complex force combination. Based on traditional Nielsen model, a unified failure model on reinforced concrete members with annular section under combined forces of tension, compression, bending, shear and torsion was formed. The advantages of this model are to consider the dowel actions of the reinforcements and reasonably to consider the shear carrying capacity of concrete, which makes the calculation results more close to the practical situations. Then, the theoretical results of this model are compared with Nielsen model and a series of experimental results of annular section members. The comparison verifies that the new model is feasible for the design and calculation of annular section members.

Key words: reinforced concrete, dowel action, failure criterion, annular section