A realistic estimation of the effective breadth of ribbed plates

In this paper a realistic estimation of the effective breadth of a stiffened plate is presented. For the estimation of the effective breadth the adopted model contrary to the models used previously takes into account the resulting inplane forces and deformations of the plate as well as the axial forces and deformations of the beam, due to combined response of the system. The analysis consists in isolating the beams from the plate by sections parallel to the lower outer surface of the plate. The forces at the interface, which produce lateral deflection and inplane deformation to the plate and lateral deflection and axial deformation to the beam, are established using continuity conditions at the interface. The solution of the arising plate and beam problems, which are nonlinearly coupled, is achieved using the analog equation method. After the solution of the plate––beams system is achieved, the distribution of the axial stresses across the plate, resulting from both the bending and the inplane action of the plate, is obtained. Integrating this distribution across the plate the values of the effective breadth are obtained. The influence of these values from the beam stiffness and their variation along the longitudinal direction of the plate are shown as compared with those obtained from various codes through numerical examples with great practical interest.