An analytical design method for walls with encased steel shapes

The design of walls or columns with several encased steel profiles as reinforcement has similarities with classical reinforced concrete, but it has also original aspects which need specific design approaches. Until now there has been experimental research and numerical models, which demonstrated the validity of those structural components, but simple methods for design have not been presented. In the proposed method, the classical truss model used to design reinforced concrete for shear is extended to involve the contribution of encased profiles to shear stiffness. This allows to distinguish the action effects in the steel profiles and in concrete and to make separate checks for shear of the steel profiles and the concrete section with transverse reinforcements. The evaluation of longitudinal shear action effects at the steel profile – concrete interface is a critical point, as it appears in the literature which reflects research projects made with very different degree of connection. A method to calculate those longitudinal shear action effects and the compression stresses at the steel profile – concrete interface is proposed. The available resistance modes to longitudinal shear are recalled in the format of Eurocode 4 and design checks are proposed. The method is assessed by comparison to experimental results obtained in the frame of the European research project SMARTCOCO.