Definitions for "Main diagonal"
Keywords:  diagonal, truss, matrix, span, corner
The diagonal cells of a matrix from upper left to lower right.
A web diagonal member joining the top and bottom chords of a truss, and taking its greatest stress when not less than one half of the span is covered by the live load.
A tension member of a truss, sloping upward towards the nearer end of the span. Main diagonals in iron bridges are not adjustable.