Dear All,
Does anyone has experience regarding to long openings in vessels ? UG-36a reproduced below asks for reinforcement against twisting. Does anyone knows how it can be dimensioned against twisting?

UG-36 a) .."When the long dimension of an
elliptical or obround opening exceeds twice the short
dimensions, the reinforcement across the short dimensions
shall be increased as necessary to provide against excessive
distortion due to twisting moment."

Shigueru