Influence Surfaces for Continuous Plates

Influence surfaces are valuable aids for the computation of moments in plates caused by concentrated loads. The influence surfaces presented in this paper have been drawn from influence coefficients computed by a numerical procedure coded for a digital computer. Four moment locations are considered in the interior panel of a continuous structure composed of nine square panels arranged three by three and supported along the edges by flexible beams which in turn are supported at their intersections by rigid columns. When the supporting beams have zero flexural and torsional stiffness, the nine-panel structure is representative of a plate supported by rigid columns at the corners of each panel. When the beams are considered to have stiffness, the structure analyzed is representative of a plate continuous on all four edges and supported on deflecting beams and rigid columns at the corners. The accuracy of the computations was checked by comparing the computer results with those obtained by a more exact method of solution. The comparison shows that the finite difference method rounds off discontinuities which occur in the more exact solution. However, a comparison of values from the two methods at some distance from a discontinuity show there is no difference between them.