Reinforcement calculations performed for vessels A4, A5, and B2 (Figures D, E, and J), are discussed in section 13-8. The rectangular vessel program only addresses those vessels in which the reinforcement on opposite side plates has the same moment of inertia. Additionally, the reinforcement for vessels A4 and B2 is assumed to be continuous, while A5 is assumed to be non-continuous.
The first reinforcement calculation is that of the maximum pitch between reinforcing member center lines. Equation 1 of UG-47 is used to set a basic maximum distance. Using this maximum value, equations (1a)-(1d) in Section 13-8 are used to obtain a maximum value for both the long and short-side plates. The minimum calculated value shall be considered the maximum distance between reinforcement center lines. In addition to the above calculations, the geometry of the reinforcement must be checked. Specifically, the width of the reinforcing members cannot physically exceed the pitch.
Once the pitch is determined, the moment of inertia of the composite section (shell and reinforcement) is determined by the Area-Moment method. The moment of inertia calculations are performed for locations where the plate is in compression, and then also performed for locations where the plate is in tension. Equation (2) of Section 13-8 is used to calculate the maximum width of the shell plate which can be used to compute the effective moments of the composite section at locations where the shell plate is in compression. At locations where the shell plate is in tension, an effective width equal to the actual pitch distance is used in the computations.