Direct Stress Analysis of Orthotropic Bridge Slabs

An approximate method of analysis of orthotropic bridge slabs is presented, enabling stresses to be obtained directly without the usual need for intermediate deflection calculation. The method uses the principle of least work, in conjunction with the assumption that the bending and twisting moments and shear forces in the plate may be represented by power series in the chordwise coordinate, the coefficients of the series being functions of the spanwise position only. The series are chosen to satisfy both the free-edge boundary conditions and the equilibrium equations for the slab, enabling the moments and shears to be expressed in terms of chosen redundant functional coefficients. By expressing the strain energy in terms of these redundant functions and minimizing the energy integral by the calculus of variations, a set of linear differential equations in the required functions is obtained, together with a complete set of boundary conditions for solution of the problem.