Civil Engineering Reference
In-Depth Information
compressive force is likely to act uniformly throughout the cross section of
the column, crushing the material. For a tall column, the compressive force
may cause the column to buckle even before its ultimate stress is reached.
If we compare columns of the same cross-sectional area and same mate-
rial, each subjected to the same compressive force, the taller the column,
the more likely it is to buckle. Since the engineer's primary job is to ensure
that the column's resistance exceeds its load, she must anticipate ultimate
strength ahead of time, and ensure that loads above this critical value are
prohibited. If the load cannot be reduced, she may select a column that
is shorter, has a larger cross-sectional area, or is made of stronger material.
TENSILE FORCE: PULLING ON A CABLE
We now turn to tension or
tensile force,
which acts by pulling on a mate-
rial
.
Let us consider a load, once again 100 kips, suspended from a steel
cable (figure 3.3). This is a worthwhile subject for bridge builders because
(0 KIPS)
50
KIPS
100
KIPS
Figure 3.3. Larger loads impose greater tensile strain.
