Bearing capacity analysis for confined concrete column with two lateral confinements

Based on the conception of confined concrete, three kinds of confined concrete column with two lateral confinements, such as two steel tubes, two lateral spiral hoops, outer spiral hoops and inner steel tube, are brought forward firstly. Then the calculation formulas of bearing capacity subjected to the axial force for the above three confined concrete column are proposed, based on the existing calculation methods of bearing capacity for the concrete column confined with spiral hoops and steel tube. The existing experimental results indicate that the proposed methods are right and valid, and can be applied in the design of the confined concrete column.