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2. Combination resistance where at any section point there
are only tangential stresses  ,  і  , acting in the same
Q y Q z M x
plane and are directed at an angle to each other and may be
calculated by the geometric summation
2
2
           .
Q y Q z M x y z

3. Combination resistance where at the section points normal and
shear stress (plane stress) simultaneously occur that can be
calculated by applying one of the theories of strength.

1.2 Oblique bending

Oblique bending is the type of bend in which the plane of
action of the bending moment does not pass through any of the
principal axes of the cross-section of the rod (fig. 1.2).
For example, the roof beams are usually loaded by force

Figure 1.2

the action plane of which forms a considerable angle to the main
axes (fig. 1.2, a-b), the same can be caused by special features of
the crosscut geometry; there are often cases when the plane of
stresses only slightly deviates from the principal axes of inertia
(for technological reasons or due to inaccuracies in the
manufacture and mounting structures).
We can distinguish flat oblique bending when all external
forces lie in one plane, and the elastic beam line - flat curve and

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