Page 61 - 4560

Figure 5.6

2
  a b  c , (5.21)
кр
where a , b and c – coefficients that depend on the material of
the rod and determined experimentally (for plastics c  ).
0
According to Yasinsky’s formula we can calculate critical stress
for rods of medium flexibility, which are widely used in many
steel and concrete structures. For steel (St3) rod average
flexibility is 40   100.
Directly proportional relationship is between the critical stress
and flexibility for rods of medium flexibility in the graph (fig.
5.6) corresponds to the oblique line area - the so-called
Yasinsky’s Line that continues Euler’s hyperbole. Rods of low
flexibility 0   40 do not count on stability as relevant critical
stress for them exceeds the liquid limit, i.e., fracture of rods is
due to loss of strength - in fig. 5.6 This section is parallel to the x-
axis.

5.5 Practical calculation of compressed rods
stability

61