Capacity of RC rectangular sections subjected to biaxial bending: simplification to an increased uniaxial bending moment

This paper proposes a new method for determining the capacity of reinforced concrete (RC) rectangular sections with doubly symmetrical reinforcement subjected to combined axial load and biaxial bending. The method is based on the simplification to an increased uniaxial bending analysis and is valid for both normal- and high-strength concretes and for different bar arrangements, which can be equal at the four corners, uniformly distributed over the contour or symmetrical at opposite faces. The proposed method has been suggested from an analytical calculation that adopts the assumption of Eurocode 2. The method was compared with theoretical results and experimental tests from the literature. The method allows reinforced concrete sections to be checked and designed in a simple but accurate way, which is very interesting for practising engineers.