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 

0
0
Q x
- If    , then M x  it follows that at a point x  x
0 0 0
M
the function   x acquires the extreme value;
- If q  , then Q  const , thus
0
M   x   Qdx C  Qx C ,
i.e. at the section that is free of distributed load, bending moment
varies linearly;
- if q  const , than
qx 2
M   x   qdxdx Cx D    Cx D ,
2
i.e. at the section loaded by uniformly distributed load, bending
moment varies according to the law of quadratic parabola.
Note that despite the distributed load   x the beam can be
q
loaded by moment distributed load of intensity   x , then the
m
equation (6.2) and (6.3) should be supplemented
2
dM   x d M   x dm   x
 Q   x  m  , x  q   x  .
dx dx 2 dx

6.3 Determination of normal stresses

Let the beam is in a state of pure bending (fig. 6.6, a). To
determine the normal stresses arising in cross-sections of beams,
the method of sections is used. The imaginary plane will cross the
beam at a distance x from the free end. Consider three aspects of
the problem

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